2018-2019 Honors Chemistry Summer ... - Greenway High …



2018-2019 Honors Chemistry Summer AssignmentDear Honors Chemistry Student,Welcome to Honors Chemistry. This class will provide you with the critical thinking and problem-solving skills to be successful in your post-high school life; whether that be college or career. This year we are going to learn lots of chemistry. In order to fit all you need to know in two semesters, we are going to get a head start. Below is a general idea about the class and your summer assignment.Chemistry is built a lot like math. Each concept we learn is the base for future concepts. It is vital that during the course of the year, you constantly study. At any point you feel lost, confused or overwhelmed, ask for help. Help can be from me, a friend who understands, or even the internet (there are some great websites to help with complicated concepts). In this class, homework is not busy work; homework is designed to help you practice the concept we are learning. The homework will have problems that review what we learned in class and prepare you for any assessment. Please complete your homework on time.The best part of chemistry is all the labs. We will conduct labs with every unit. It is important that you complete all pre-lab material prior to entering a lab. Reading all the procedures prepares you for what to expect during the lab.The following pages are your summer assignment for this class. Please complete each worksheet and memorize the elements on the first page (name, symbol, and atomic number) by Wednesday, August 8, 2018. You will be assessed on all summer assignment material on Friday August 10, 2018.If you have any questions over the semester, you can email me at Melissa.kestle@.If you are doing your back to school shopping I would recommend the following for chemistry:A thick binder (2-3 inches)Pencil, pens, highlightersA calculator that can work in scientific notationSpiral notebook for notesComposition notebook for labs** If you are unable to purchase any of the above items by the second day of school, please let me know so I can have extras on hand for you to use.I look forward to having a great year with each and every one of you.Melissa Kestle Greenway High School Honors ChemistrySummer Assignment InformationPlease sign up for Kestle’s Honors Chemistry Remind: Using the phone app: rmd.at/gwhcUsing Text: @gwhc to 81010Please log onto our Google Classroom Page: code is kkdvdadAll Worksheets for Summer Assignment (you will receive a hard copy as well) Readings for Summer AssignmentHonors Chemistry 2018-2019Summer Assignment Student Information PageThis page will be placed on the top of the assignment you turn in.You will only turn in the worksheets and lab, please keep all the readings.Name: Hour: Date Turned In: Score for summer assignment: 4477384213026How were sailors able to measure the depths of seas? Back in the days before all the electronic gadgets for measuring depth and locating undersea objects existed, the "fathom" was the unit of measurement for depth. A rope was knotted every sixfeet and the end was dropped over the side of the ship. You could tell how deep the water was by how many knots went under the water before the rope hit bottom. Today, we just turn on an instrument and read the depth to a high level of accuracy.Length and VolumeLength is the measurement of the extent of something along its greatest dimension. The SI basic unit of length, or linear measure, is the meter (m). All measurements of length may be made in meters, though the prefixes listed in various tables will often be more convenient. The width of a room may be expressed as about 5 meters (m), whereas a large distance, such as the distance between New York City and Chicago, is better expressed as 1150 kilometers (km). Very small distances can be expressed in units such as the millimeter or the micrometer. The width of a typical human hair is about 20 micrometers (μm).Volume is the amount of space occupied by a sample of matter. The volume of a regular object can be calculated by multiplying its length by its width by its height. Since each of those is a linear measurement, we say that units of volume are derived from units of length. The SI unit of volume is the cubic meter (m3), which is the volume occupied by a cube that measures 1 m on each side. This very large volume is not very convenient for typical use in a chemistry laboratory. A liter (L) is the volume of a cube that measures 10 cm (1 dm) on each side. A liter is thus equal to both 1000 cm3 (10 cm × 10 cm × 10 cm) and to 1 dm3. A smaller unit of volume that is commonly used is the milliliter (mL – note the capital L which is a standard practice). A milliliter is the volume of a cube that measures 1 cm on each side. Therefore, a milliliter is equal to a cubic centimeter (cm3). There are 1000 mL in 1 L, which is the same as saying that there are 1000 cm3 in 1 dm3.To determine the volume of a liquid, usually in a graduated cylinder, you look at the bottom curve which is called the meniscus, the curve seen at the top of a liquid in response to its container. When you read a scale on the side of a container with a meniscus, such as a graduated cylinder or volumetric flask, it's important that the measurement accounts for the meniscus. Measure so that the line you are reading is evenwith the center of the meniscus. For water and most liquids, this is the bottom of the meniscus.Mass and Weight4412615181010How is he floating?One of the many interesting things about travel in outer space is the idea of weightlessness. If something is not fastened down, it will float in mid-air. Early astronauts learned that weightlessness had bad effects on bone structure. If there was no pressure on the legs, those bones would begin to lose mass. Weight provided by gravity is needed to maintain healthy bones.Specially designed equipment is now a part of every space mission, so the astronauts can maintain good body fitness.Mass is a measure of the amount of matter that an objectcontains. The mass of an object is made in comparison to the standard mass of 1 kilogram. The kilogram was originally defined as the mass of 1 L of liquid water at 4°C (volume of a liquid changes slightly with temperature). In the laboratory, mass is measured with an electric balance which must be calibrated with a standard mass so that its measurements are accurate.5289546359610Other common units of mass are the gram and the milligram. A gram is 1/1000th of a kilogram, meaning that there are 1000 g in 1 kg. A milligram is 1/1000th of a gram, so there are 1000 mg in 1 g.Mass is often confused with the term weight. Weight is a measure of force that is equal to the gravitational pull on an object. The weight of an object is dependent on its location. On the moon, the force due to gravity is about one sixth that of the gravitational force on Earth. Therefore, a given object will weigh six times more on Earth than it does on the moon. Since mass is dependent only on the amount of matter present in an object, mass does not change with location. Weight measurements are often made with a spring scale by reading the distance that a certain object pulls down and stretches a spring.5486401677264057650-238225Temperature and Temperature ScalesTouch the top of the stove after it has been on, and it feels hot. Hold an ice cube in your hand and it feels cold.Why? The particles of matter in a hot object are movingmuch faster than the particles of matter in a cold object. An object’s kinetic energy is the energy due to motion. The particles of matter that make up the hot stove have a greater amount of kinetic energy than those in the ice cube.Temperature is a measure of the average kinetic energy of the particles in matter. In everyday usage, temperature indicates a measure of how hot or cold an object is. Temperature is an important parameter in chemistry. When a substance changes from solid to liquid, it is because there was an increase in the temperature of the material.Chemical reactions usually proceed faster if the temperature is increased. Many unstable materials (such as enzymes) will be viable longer at lower temperatures.Temperature Scales5486407053157238901281008The first thermometers were glass and contained alcohol, which expanded and contracted as the temperature changed. The German scientist, Daniel Gabriel Fahrenheit, used mercury in the tube. The Fahrenheit scale was first developed in 1724 and tinkered with for some time after that. The main problem with this scale is the arbitrary definitions of temperature. The freezing point of water was defined as 32°F and the boiling point as 212°F. The Fahrenheit scale is typically not used for scientific purposes.Daniel Gabriel FahrenheitThe Celsius scale of the metric system is named after Swedish astronomer Anders Celsius (1701-1744). The Celsius scale sets the freezing point and boiling point of water at 0°C and 100°C respectively. The distance between those two points is divided into 100 equal intervals, each of which is one degree. Another term sometimes used for the Celsius scale is “centigrade” because there are 100 degrees between the freezing and boiling points of water on this scale. However, the preferred term is “Celsius.”Anders CelsiusLord KelvinThe Kelvin temperature scale is named after Scottish physicist and mathematician Lord Kelvin (1824-1907). It is based on molecular motion, with the temperature of 0 K, also known as absolute zero, being the point where all molecular motion ceases. The freezing point of water on the Kelvin scale is 273.15 K, while the boiling point is 373.15 K. Notice that here is no “degree” used in the temperature designation. Unlike the Fahrenheit and Celsius scales where temperatures are referred to as “degrees F” or “degrees C,” we simply designated temperatures in the Kelvin scale as kelvins.5791200-439485As can be seen by the 100 kelvin difference between the two, (boiling points and freezingpoint), a change of one degree on the Celsius scale is equivalent to the change of one kelvin on the Kelvin scale. Converting from one scale to another is easy, as you simply add 273 to gofrom Celsius to Kelvin or subtract 273 to go from Kelvin to Celsius.Many properties of matter are quantitative; that is, they are associated with numbers. When a number represents a measured quantity, the unit of that quantity must always be specified. To say that the length of a pencil is 17.5 is meaningless; however, saying it is 17.5 cm specifies the length. The units used for scientific measurements are those of the metric system.3597275-33446The metric system was developed in France during the late 1700s and is the most common form of measurement in the world. There are a few countries, The United States of America, that do not follow the metric system; we use the English system. Over the years the use of the metric system has become more common; just look at a can of soda, there are indications of the metric system.Metric PrefixesConversions between metric system units are straightforward because the system is based on powers of ten. For example, meters, centimeters, and millimeters are all metric units of length.There are 10 millimeters in 1 centimeter and 100 centimeters in 1 meter. Metric prefixes are used to distinguish between units of different size. These prefixes all derive from either Latin or Greek terms.Can of Soda showing both English (oz) & Metric (mL) unitsThe tables above lists the most common metric prefixes and their relationship to the central unit that has no prefix.There are a couple of odd little practices with the use of metric abbreviations. Most abbreviations are lower-case. We use “m” for meter and not “M”. However, when it comes to volume, the base unit “liter” is abbreviated as “L” and not “l”. So we would write 3.5 milliliters as 3.5 mL.As a practical matter, whenever possible you should express the units in a small and manageable number. If you are measuring the weight of a material that weighs 6.5 kg, this is easier than saying it weighs 6500 g or 0.65 dag. All three are correct, but the kg units in this case make for a small and easily managed number. However, if a specific problem needs grams instead of kilograms, go with the grams for consistency.Converting (Dimensional Analysis)548640-44984How can a number of track laps be converted to a distance in meters?You are training for a 10-kilometer run by doing laps on a 400-meter track. You ask yourself “How many times do I need to run around this track in order to cover ten kilometers?” (More than you realize & one of the many reasons I don’t run). By using dimensional analysis, you can easily determine the number of laps needed to cover the 10 k distanceConversion FactorsMany quantities can be expressed in several different ways. The English of system measurement of 4 cups is also equal to 2 pints, 1 quart, and 0.25 of a gallon.4 cups = 2 pints or 1 quart or 0.25 gallonNotice that the numerical component of each quantity is different, while the actual amount of material that it represents is the same. That is because the units are different. We can establish the same set of equalities for the metric system:1 meter = 10 decimeters or 100 centimeters or 1000 millimeters The metric system’s use of powers of 10 for all conversions makes this quite simple.Whenever two quantities are equal, a ratio can be written that is numerically equal to 1. Using the metric examples above:1m= 100cm= 1m = 1 100cm1000mm1mThe 1 m/100 cm is called a conversion factor. A conversion factor is a ratio of equivalent measurements. Because both 1 m and 100 cm represent the exact same length, the value of the conversion factor is 1. The conversion factor is read as “1 meter per 100 centimeters”. Other conversion factors from the cup measurement example can be:4 cups =2 pints =1 quart= 12 pints1 quart? gallonSince the numerator and denominator represent equal quantities in each case, all are valid conversion factors.Scientific Dimensional AnalysisConversion factors are used in solving problems in which a certain measurement must be expressed with different units. When a given measurement is multiplied by an appropriate conversion factor, the numerical value changes, but the actual size of the quantity measured remains the same. Dimensional analysis is a technique that uses the units (dimensions) of the measurement in order to correctly solve problems. Dimensional analysis is best illustrated with an example.Set-Up# unit looking for = Given xUnknown=1Conversion factorThe unit you are looking for MUST match the unit for your unknown. The unit for your given MUST match the unit on the conversion factor356490716285Sample Problem 1:How many seconds are in a day?Step 1: List the known quantities and plan theproblem. Known1 day = 24 hours1 hour = 60 minutes1 minute = 60 secondsUnknown1 day =? secondsThe known quantities above represent the conversion factors that we will use. The first conversion factor will have day in the denominator so that the “day” unit will cancel. The second conversion factor will then have hours in the denominator, while the third conversion factor will have minutes in the denominator. As a result, the unit of the last numerator will be seconds, and that will be the units for the answer.Step 2: Calculate# secs = 1 day x 24 hours x 60 min x 60 sec = 86,400 sec1 day1 hour1 minApplying the first conversion factor, the “day” unit cancels and 1 x 24 = 24. Applying the second conversion factor, the “hour” unit cancels and 24 x 60 = 1440. Applying the third conversion factor, the “min” unit cancels and 1440 x 60 = 86,400. The unit that remains is “s” for seconds.Step 3: Think about your result.Seconds is a much smaller unit of time than a day, so it makes sense that there are a very large number of seconds in one day.Metric Unit ConversionsThe metric system’s many prefixes allow quantities to be expressed in many different units. Dimensional analysis is useful to convert from one metric system unit to another.Sample Problem 2:5562600370957A particular experiment requires 120 mL of a solution. The teacher knows that he will need to make enough solution for 40 experiments to be performed throughout the day.How many liters of solution should he prepare?Step 1: List the known quantities and plan the problem. Known1 experiment requires 120 mL1 L = 1000 mLUnknownL of solution for 40 experimentSince each experiment requires 120 ml of solution and the teacher needs to prepare enough for 40 experiments, multiply 120 by 40 to get 4800 mL of solution needed. Now you must convert ml to L by using a conversion factor.Step 2: Calculate# L = 4800 mL x1 L= 4.8 L1000 mLNote that conversion factor is arranged so that the mL unit is in the denominator and thus cancels out, leaving L as the remaining unit in the answer.Step 3: Think about your result.A liter is much larger than a milliliter, so it makes sense that the number of liters required is less than the number of milliliters.Two-Step Metric Unit ConversionsSome metric conversion problems are most easily solved by breaking them down into more than one step. When both the given unit and the desired unit have prefixes, one can first convert to the simple (un-prefixed) unit, followed by a conversion to the desired unit. An example will illustrate this method.Sample Problem 3: Two-Step Metric Conversion Convert 4.3 km to cm.Step 1: List the known quantities and plan the problem.Known1 m = 100 cm1 km = 1000 mUnknown4.3 cm =? kmYou may need to consult a table for the multiplication factor represented by each metric prefix. First convert cm to m, followed by a conversion of m to km.Step 2: Calculate# of cm = 4.3 km x 1000 m x 100 cm = 430,000 cm1 km1 mEach conversion factor is written so that unit of the denominator cancels with the unit of the numerator of the previous factor.Step 3: Think about your result.A centimeter is a smaller unit of length than a kilometer, so the answer in centimeters is larger than the number of kilometers given.The Magic SentenceThere are many tools that can be used to make your life in chemistry easier; one is the magic sentence to learn the metric prefixes and their values. And it goes like this:47472598686King Hector Died Monday Drinking Chocolate Milk King (kilo)Hector (hector)Died (deca/deka)Monday (meter/gram/liter) Drinking (deci) Chocolate (centi)Milk (milli)Scientific Notation52736753730How far is the Sun from Earth?Astronomers are used to really big numbers. While the moon is only 406,697 km from earth at its maximum distance, the sun is much further away (150 million km). Proxima Centauri, the star nearest the earth, is 39, 900,000, 000, 000 km away and we have just started on long distances. On the other end of the scale, some biologists deal with very small numbers: a typical fungus could be as small as 30 μmeters (0.000030 meters) in length and a virus might only be 0.03 μmeters (0.00000003 meters) long.Scientific NotationScientific notation is a way to express numbers as the product of two numbers: a coefficient and the number 10 raised to a power. It is a very useful tool for working with numbers that are either very large or very small. As an example, the distance from Earth to the Sun is about 150,000,000,000 meters –a very large distance indeed. In scientific notation, the distance is written as 1.5 x 1011 m. The coefficient is the 1.5 and must be a number greater than or equal to 1 and less than 10. The power of 10, or exponent, is 11 because you would have to multiply 1.5 by 1011to get the correct number. Scientific notation is sometimes referred to as exponential notation.When working with small numbers, less than zero, we use a negative exponent. So 0.1 meters is 1 x 10-1 meters. Note the use of the leading zero (the zero to the left of the decimal point). That digit is there to help you see the decimal point more clearly. The figure 0.01 is less likely to be misunderstood than .01 where you may not see the decimal. When working with large numbers, greater than zero, we use a positive exponent. So 10 meters is 1.0 x 101.The exponent represents the number of places the decimal point moves, not the number of zeroes in the number. If you move the decimal place to the left you add to the exponent the same number of places you moved; if you are moving the decimal to the right you subtract from the exponent the same number of places you moved. This is often referred to as LARS, (left – add and right – subtract).475170461097How do police officers identify criminals?After a bank robbery has been committed, police will ask witnesses to describe the robbers. They will usually get some answer such as “medium height.” Others may say “between 5 foot 8 inches and 5 foot 10 inches.” In both cases, there is a significant amount of uncertainty about the height of the criminals.Measurement UncertaintyThere are two types of numbers in the scientific world, exact numbers and inexact numbers. Exact numbers are numbers whose values are known exactly. For example, there are 12 in a dozen and 1000 grams in 1 kg.Inexact numbers have values with some uncertainty. If you give 10 students each a dime and tell them to use a triple beam balance to obtain the mass of their dime, you will slightly varying masses. The reason for the differences may be due to equipment error, the balances not being calibrated equally, or human error, reading the balance wrong. Uncertainties always exist in measured quantities. The amount of uncertainty depends both upon the skill of the measurer and upon the quality of the measuring tool. While some balances are capable of measuring masses only to the nearest 0.1 g, other highly sensitive balances are capable of measuring to the nearest 0.001 g or even better. Many measuring tools such as rulers and graduated cylinders have small lines which need to be carefully read in order to make a measurement.The figure to the left shows two rulers making the same measurement of an object (indicated by the arrow). With either ruler, it is clear that the length of the object is between 2 and 3 cm. The bottom ruler contains no millimeter markings. With that ruler, the tenths digit can be estimated and the length may be reported as 2.5 cm. However, another person may judge that the measurement is 2.4 cm or perhaps 2.6 cm. While the 2 is known for certain, the value of the tenths digit is uncertain.The top ruler contains marks for tenths of a centimeter (millimeters). Now the same object may be measured as 2.55 cm. The measurer is capable of estimating the hundredths digit because he can be certain that the tenths digit is a 5. Again, another measurer may report the length to be2.54 cm or 2.56 cm. In this case, there are two certain digits (the 2 and the 5), with the hundredths digit being uncertain. Clearly, the top ruler is a superior ruler for measuring lengths as precisely as possible.4469129213218Precision and AccuracyThe terms precision and accuracy are often used in discussing the uncertainties of measured values. Precision is the measure of how closely individual measurements agree with one another. Accuracy refers to how closely individual measurements agree with the correct or “true” value. Refer to figure above for a visual representation of precision and accuracy.Significant Figures507301585110How fast do you drive?As you enter the town of Jacinto City, Texas, the sign below tells you that the speed limit is 30 miles per hour. But what if you happen to be driving 31 miles an hour? Are you in trouble? Probably not, because there is a certain amount of leeway built into enforcing the regulation. Most speedometers do not measure the vehicle speed very accurately and could easily be off by a mile or so (on the other hand, radar measurements are much more accurate). So, a couple of miles/hour difference won’t matter that much. Just don’t try to stretch the limits any further unless you want a traffic ticket.rulerThe significant figures in a measurement consist of all the certain digits in that measurement plus one uncertain or estimated digit. In the ruler illustration below, the bottom ruler gives a length with 2 significant figures, while the top gives a length with 3 significant figures. In a correctly reported measurement, the final digit is significant but not certain. Insignificant digits are not reported. With either ruler, it would not be possible to report the length as 2.553 cm as there is no possible way that the thousandths digit could be estimated. The 3 is not significant and would not be reported.When you look at a reported measurement, it is necessary to be able to count the number of significant figures. The table below details the rules for determining the number of significant figures in a reported measurement. For the examples in the table below, assume that the quantities are correctly reported values of a measured quantity.Significant Figure RulesRuleExamples1. All nonzero digits in a measurement are significant237 has three significant figures.1.897 has four significant figures.2. Zeroes that appear between other nonzero digits are always significant.39,004 has five significant figures.5.02 has three significant figures3. Zeroes that appear in front of all of the nonzero digits are called left-endzeroes. Left-end zeroes are never significant0.008 has one significant figure.0.000416 has three significant figures.4. Zeroes that appear after all nonzero digits are called right-end zeroes. Right-end zeroes in a number that lacks a decimal point are not significant.140 has two significant figures.75,210 has four significant figures.5. Right-end zeroes in a number with a decimal point are significant. This is true whether the zeroes occur before or after the decimal point.620.0 has four significant figures.19.000 has five significant figuresIt needs to be emphasized that to say a certain digit is not significant does not mean that it is not important or can be left out. Though the zero in a measurement of 140 may not be significant, the value cannot simply be reported as 14. An insignificant zero functions as a placeholder for the decimal point. When numbers are written in scientific notation, this becomes more apparent. The measurement 140 can be written as 1.4 ×102 with two significant figures in the coefficient. For a number with left-end zeroes, such as 0.000416, it can be written as 4.16 × 10?4 with 3 significant figures. In some cases, scientific notation is the only way to correctly indicate the correct number of significant figures. In order to report a value of 15,000,000 with four significant figures, it would need to be written as 1.500 × 107. The right-end zeroes after the 5 are significant. The original number of 15,000,000 only has two significant figures.Adding and Subtraction Significant FiguresFor addition and subtraction, look at the decimal portion (i.e., to the right of the decimal point) of the numbers ONLY. Here is what to do:Count the number of significant figures in the decimal portion of each number in the problem. (The digits to the left of the decimal place are not used to determine the number of decimal places in the final answer.)Add or subtract in the normal fashion.Round the answer to the LEAST number of places in the decimal portion of any number in the problem.Multiplying and Dividing Significant FiguresThe following rule applies for multiplication and division:The LEAST number of significant figures in any number of the problem determines the number of significant figures in the answer.This means you MUST know how to recognize significant figures in order to use this rule.Percent Erro r4773929237554Percent ErrorHow does an electrical circuit work?A complicated piece of electronics equipment may contain several resistors whose role is to control the voltage and current in the electrical circuit. Too much current and the apparatus malfunctions. Too little current and the system simply doesn’t perform. The resistors values are always given with an error range. A resistor may have a stated value of 200 ohms, but a 10% error range, meaning the resistance could be anywhere between 195-205 ohms. By knowing these values, an electronics person can design and service the equipment to make sure it functions properly.Percent ErrorAn individual measurement may be accurate or inaccurate, depending on how close it is to the true value. Suppose that you are doing an experiment to determine the density of a sample of aluminum metal. The accepted value of a measurement is the true or correct value based on general agreement with a reliable reference. For aluminum the accepted density is2.70g/cm3. The experimental value of a measurement is the value that is measured during the experiment. Suppose that in your experiment you determine an experimental value for the aluminum density to be 2.42 g/cm3. The error of an experiment is the difference between the experimental and accepted values.2304414184865If the experimental value is less than the accepted value, the error is negative. If the experimental value is larger than the accepted value, the error is positive. Often, error is reported as the absolute value of the difference in order to avoid the confusion of a negative error. The percent error is the absolute value of the error divided by the accepted value and multiplied by 100%.2248852154849If the experimental value is equal to the accepted value, the percent error is equal to 0. As the accuracy of a measurement decreases, the percent error of that measurement rises.Physical Properties of Matter2214664539417Let’s begin our study of chemistry by examing some fundamental ways in which matter is classified and described. There are two principle ways of classifying matter: its physical state and its composition (chemical).Both of these men are skiing, but the man on the left is skiing on snow while the man on the right is skiing on sand. Snow and sand are both kinds of matter, but they have different properties. What are some ways snow and sand differ? One difference is the temperature at which they melt. Snow melts at 0°C, whereas sand melts at about 1600°C! The temperature at which something melts is its melting point. Melting point is just one of many physical properties of matter.Extensive and Intensive Properties5677534222475How much is twenty dollars really worth?I agree to mow someone’s lawn for twenty dollars (it’s a fairly big yard). When they pay me, they give me a $20 bill. It doesn’t matter whether the bill is brand new or old, dirty, and wrinkled – all these bills have the same value of $20. If I want more $20 bills, I have to mow more lawns. I can’t say, “This particular bill is actually worth more than $20.” To have more money, I have to put in more work.Extensive PropertiesSome properties of matter depend on the size of the sample, while some do not. An extensive property is a property that depends on the amount of matter in a sample. The mass of an object is a measure of the amount of matter that an object contains. A small sample of a certain type of matter will have a small mass, while a larger sample will have a greater mass. Another extensive property is volume. The volume of an object is a measure of the space that is occupied by that object.548640138617The figure below illustrates the extensive property of volume. The pitcher and glass both contain milk. The pitcher holds approximately two quarts and the glass will hold about 8 ounces of milk. The same milk is in each container. The only difference is the amount of milk contained in the glass and in the pitcherIntensive Properties565467576704The electrical conductivity of a substance is a property that depends only on the type of substance. Silver, gold, and copper are excellent conductors of electricity, while glass and plastic are poor conductors. A larger or smaller piece of glass will not change this property.An intensive property is a property of matter that depends only on the type of matter in a sample and not on the amount. Other intensive properties include color, temperature, density, and solubility.The copper wire shown in the picture below has a certain electrical conductivity. You could cut off the small end sticking out and it would have the same conductivity as the entire long roll of wire shown here. The conductivity is a property of the copper metal itself, not of the length of the wire.Physical Properties of MatterWhy are drag car standards constantly reinforced?Drag racing is a highly competitive (and expensive) sport. There are a variety of classes of vehicles, ranging from stock classes (depending on car weight, engine size, and degree of engine modification) all the way up to the Top Fuel class with weights of over two thousand pounds and capable of top speeds of well over 300 miles/hour at the end of the quarter-mile. The standards for each class are well-defined and frequent checks are made of engine dimensions and components to insure that the rules are followed.54863839415A physical property is a characteristic of a substance that can be observed or measured without changing the identity of the substance. Silver is a shiny metal that conducts electricity very well. It can be molded into thin sheets, a property called malleability. Salt is dull and brittle and conducts electricity when it has been dissolved into water, which it does quite easily. Physical properties of matter include color, hardness, malleability, solubility, electrical conductivity, density, melting points, and boiling points.For the elements, color does not vary much from one element to the next. The vast majority of elements are colorless, silver, or gray. Some elements do have distinctive colors: sulfur and chlorine are yellow, copper is (of course) copper-colored and elemental bromine is red.Density can be a very useful parameter for identifying an element. Of the materials that exist as solids at room temperature, iodine has a very low density compared to zinc, chromium and tin. Gold has a very high density, as does platinum.Hardness helps determine how an element (especially a metal) might be used. Many elements are fairly soft (silver and gold, for example) while others (such as titanium, tungsten, and chromium) are much harder. Carbon is an interesting example of hardness. In graphite (the “lead” found in pencils) the carbon is very soft, while the carbon in a diamond is roughly seven times as hard.18180042262934996815100563Chemical Properites of MatterChemical properties are properties that can be measured or observed only when matter undergoes a change to become an entirely different kind of matter. For example, the ability of iron to rust can only be observed when iron actually rusts. When it does, it combines with oxygen to become a different substance called iron oxide. Iron is very hard and silver in color, whereas iron oxide is flakey and reddish brown. Besides the ability to rust, other chemical properties include reactivity and flammability.Reactivity is the ability of matter to combine chemically with other substances. Some kinds of matter are extremely reactive; others are extremely unreactive. For example, the metal magnesium is very reactive, even with water. When a pea-sized piece of magnesium is added to a small amount of water, it reacts explosively. In contrast, noble gases such as helium almost neverreact with any other substances. The chart below shows the reactivity of several different metals. The metals range from very reactive to very unreactive.548640-1263Flammability is the ability of matter to burn. When matter burns, it combines with oxygen and changes to different substances. Wood is an example of flammable matter. When wood burns, it changes to ashes, carbon dioxide, water vapor, and other gases. You can see ashes in the wood fire pictured to the right. The gases are invisible.DensityOne of the ways a scientist identifies a substance is by calculating its density. Density is defined as the mass of an object in a given unit of volume. This means that the property of density tells how tightly matter is packed in a substance. You have probably heard of the famous riddle, “Which weighs more, a pound of feathers or a pound of lead?” At first many people say, a pound of lead. But the answer is that they weigh the same (one pound each). This riddle illustrates the physical property of matter called density. The density of lead is much greater than the density of feathers. A pound of lead would be a small cube, while a pound of feathers would be in a much larger box. Another way of saying this is that lead has more matter packed in a smaller space than the feathers have.What is Density?The idea of density can be expressed in mathematical terms. The formula for density is: density = mass divided by volume (d = m/v). So, density is found by dividing mass of an object by its volume. The units for density are usually grams per cubic centimeter (g/cm3) or grams per milliliter (g/mL). Mass is the amount of matter in an object, measured with a balance in the base unit of grams; however volume is the amount of space an object occupies and is measured in the liquid base unit as milliliters (mL) and solid base unit of cubic centimes (cm3) . One milliliter is equal to one cubic centimeter. For example, the mass of an object is 30 grams and its volume is 15 milliliters. We find the density of the object by dividing 15 into 30. The density would be recorded as 2 grams per milliliters or 2 g/mL.Here is the same example using the proper set up and math:D = mVD = ?m = 30 g V = 15 mLD = 30 g .15mLD = 2.00 g/mLWater DisplacementMany of the solid objects we measure in class have unusual or small shapes. Therefore, we use a method called water displacement to measure the objects volume. The process of this method requires a graduated cylinder to be filled with a set volume of water, the object is then carefully slid into the graduated cylinder, and the difference in water is recorded as the volume of the object. For example, the graduated cylinder is filled to 50 milliliters, the object is added and the water moves to 100 milliliters. We find the object’s volume by subtracting the initial volume of water, 50 mL, from the volume of the water with the object, 100 mL; the objects volume is 50 mL. Using conversions, you can determine the object as having a volume of 50 cm3.initial volumeof water 50 mLdifference inthe water’s volume before and after thefinal volumeof water with objectobjectUses of DensityThe density of any particular substance is always the same, regardless of the size of the object being measured. Because of this, density is used to identify substances. For example, gold has density of 19.32 g/cm3, copper has a density of 8.9 g/cm3, and water has a density of 1 g/mL. So, how can this be used? An example can be seen with the two metals, silver and polished aluminum.They both look alike and have many common properties, so how can we tell them both apart? We measure their densities by first finding their mass and volumes and plugging them into our formula for density and then comparing our answer to the known densities of the metals. Aluminum has a density of 2.7 g/cm3and silver has a much heavier density.You can also use density to determine the amount of gold found in a piece of jewelry. Gold alone is too soft to use in the making of jewelry so it is often mixed with copper to make it stronger. This mixture is called an alloy. The gold alloy is not worth as much as pure gold. To determine how much copper is in the gold alloy, you must first find the mass of the jewelry. Then, measure the volume of the jewelry using the water displacement method due to its irregular shape. When the mass is divided by volume, density can be determined. If a piece of jewelry is 50% copper and 50% gold, its density would be 12.22 g/cm3. If its density is less than this, it would have more copper in it than gold and the value would be lower. If its density is more than this, it would have more gold in it than copper and the value would be higher.The densities of liquid can show how much matter is dissolved in them. For example, the liquid in a car battery is a mixture of water and sulfuric acid. The density of this liquid is about 1.3 g/mL. When a car battery is in good condition, the liquid is at its highest density. As the battery ages and loses its ability to produce electricity, the density of the water drops. The condition of the battery can be determined by measuring the liquid's density. The higher the density, the better the battery's condition.Service stations have a tube with a float in it called a hydrometer. This device measures the density of the battery liquid. There is a rubber bulb on one end of the tube that the attendant squeezes to draw battery liquid into the device and the float floats in the liquid. In a more dense liquid, more of the float remains above the surface. The float rides deeper in less dense liquids. Marks on the float tell what the liquid's density is. Low density would suggest a bad battery. Hydrometers can also be used to determine the densities of other liquids such as milk sugar, alcohol, or pollutants in water.Another use of density can be found in the sports gym. An athletic trainer can determine the percentage of body fat in an athlete's body. The mass of the athlete is first determined on a scale. He or she is then immersed in a tub of water to determine their volume. The density of the athlete is calculated. If the percent of the body fat is too high, the trainer will recommend a diet and exercise program.Densities also show which objects will float in various liquids. An object that can float is often called buoyant. Buoyancy is a simple way of relating the density of one object to another, since the object with greater density will sink and the object with the smaller density will float. In other words, the rule is objects of lower density will float on liquids of higher density. For example, most dry wood is less dense than water, since it has many air pockets. A block of dry wood will, therefore, float in water. If the wood becomes water soaked, the air in the wood is replaced with water. The wood then becomes denser than water and will sink.Density applies to all forms of matter. Seawater is denser than fresh water. Cold air is denser than warm air. Mercury, a liquid, is denser than steel a hard, tough, solid. As you can see, density is an important physical property of matter.States of Matter5330825506761In addition to these properties, other physical properties of matter include the state of matter. States of matter include liquid, solid, and gaseous states and they differ in simple observable properties. A liquid has a distinct volume independent of its container but has no specific shape – it can take on the shape of any container. A solid has both a definite shape and a definite volume. A gas, also called a vapor, has no fixed volume or shape; rather it conforms tothe volume and shape of its container. The properties of matter can be understood at the molecular level: the figure to the right shows each state of matter at the molecular position of MatterMost forms of matter that we encounter-for example, the air we breathe (gas), the gasin our cars (liquid) and the sidewalk on which we walk (solid) – are not chemically pure. We can separate matter into different pure substances. Pure substances (substances) are matter that has distinct properties and a composition that does not vary from sample to sample. Water and table salt (sodium chloride, NaCl), the primary components of seawater, are examples of pure substances.All substances are either elements or compounds. Elements cannot be decomposed (broken down) into simpler substances. On the molecular level, each element is composed of a single type of atom. Compounds are substances composed of two or more elements; they contain two or more kinds of atoms. Water, for example, is a compound composed of the elements of hydrogen and oxygen. Mixtures are combinations of two or more substances in which each substance retains its chemical identity.1965699233419ElementsCurrently there are 117 known elements and you have to know them all. Just kidding, only the first 20 or so. These 117 elements vary widely in their abundance. For example, only 5 elements – oxygen, silicon, aluminum, iron and calcium – account for over 90% of the earth’s crust. Also, only 3 elements – oxygen, carbon and hydrogen – account for over 90% of the human body.Some of the more common elements are listed below with their chemical symbols. Chemical symbols are abbreviations of a chemical and consist of one or two letters, with the first letter being capitilized. These symbols are mostly derivied from the English name with some from foreign names. All known elements and their symbols are listed on the periodic table of elements – this table will soon be your best friend in chemistry, please be poundsMost elements can interact with other elements to form compounds. Compounds consist of two or more elements, and compounds always have the same elemental composition, that is, elements will combine in whole number ratios, and each compound has its own unique composition. For example, carbon monoxide, CO, consists of one carbon atom and one oxygen atom; whereas carbon dioxide, CO2, consists of one carbon atom and two oxygen atoms. Both carbon monoxide and carbon dioxide are composed of carbon and oxygen, but the number of each element is different. The extra oxygen on carbon dioxide is what makes it distinctly different from carbon monoxide and why CO2 won’t kill you.MixturesMost of the matter we encounter on a daily basis are mixtures of different substances. As defined earlier, each substance in a mixture retains its own chemical identity and its own properties. In contrast to a pure substance that has a fixed composition, the composition of a mixture can change. For example, you can go into Starbucks and order a coffee black or with cream and sugar or with caramel, mocha and whipped cream, (the best way). The individual substances make up the mixture are called the components of the mixture.Homogeneous mixtures are uniform throughout – you cannot see the individual components, for example, the air you breathe or salt dissolved in water. Homogeneous mixtures are also called solutions, although we assume a solution is a liquid, it can exist in any state.3731324725214Some mixtures do not have the same composition, properties, and appearance throughout and are called heterogeneous mixtures. Heterogeneous mixtures – such as wood, rocks, and trail mix – vary in texture and appearance; you can identify all the components of the mixture easily. Suspensions are heterogeneous mixtures in which some of the particles settle out of the mixture upon standing. The particles in a suspension are far larger than those of a solution, so gravity is able to pull them down out of the solution. Unlike a solution, the dispersed particlescan be separated from the dispersion medium by filtering.Separation of MixturesBecause each component of a mixture retains its own properties, we can separate a mixture into its components by taking advantage of their properties. There are several techniques we can use to separate mixtures.MagnetismIf you have a mixture of sand and iron shavings, you can use a magnet to pull out the iron, leaving the sand.5486405302Chromatography is the separation of a mixture by passing it in solution or suspension or as a vapor (as in gas chromatography) through a medium in which the components move at different rates. Thin-layer chromatography is a special type of chromatography used for separating and identifying mixtures that are or can be colored, especially pigments.4321682481094Distillation is an effective method to separate mixtures comprised of two or more pure liquids. Distillation is a purification process where the components of a liquid mixture are vaporized and then condensed and isolated. In simple distillation, a mixture is heated and the most volatile component vaporizes at the lowesttemperature. The vapor passes through a cooled tube (a condenser), where it condenses back into its liquid state. The condensate that is collected is called distillate.In figure to the right, we see several important pieces of equipment. There is a heat source, a test tube with a one-hole stopper attached to a glass elbow and rubber tubing. The rubber tubing is placed into a collection tube which is submerged in cold water. There are other more complicated assemblies for distillation that can also be used, especially to separate mixtures, which arecomprised of pure liquids with boiling points that are close to one another.548640-70199Evaporation is a technique used to separate out homogenous mixtures where there is one or more dissolved solids. This method drives off the liquid components from the solid components. The process typically involves heating the mixture until no more liquid remains. Prior to using this method, the mixture should only contain one liquid component, unless it is not important to isolate the liquid components. This is because all liquid components will evaporate over time. This method is suitable to separate a soluble solid from a liquid. In many parts of the world, table salt is obtained from the evaporation of sea water. The heat for the process comes from the sun.521652549602Filtration is a separation method used to separate out pure substances in mixtures comprised of particles some of which are large enough in size to be captured with a porous material. Particle size can vary considerably, given the type of mixture. For instance, stream water is a mixture that contains naturally occurring biological organisms like bacteria, viruses, and protozoans. Some water filters can filter out bacteria, the length of which is on the order of 1 micron. Other mixtures, like soil, have relatively large particle sizes, which can be filtered through something like a coffee filter.Changes to Matter5387975730638As with the physical and chemical properties of matter, substances can also undergo changes. Matter can change in two ways – physically or chemically. A physical change to matter changes its physical appearance, but its chemical composition remains the same. A chemical change occurs with the substance is transformed into a chemically different substance, sometimes referred to as a chemical reaction.Chemical ChangeDo you like to cook?Cooking is a valuable skill that everyone should have. Whether it is fixing a simple grilled cheese sandwich or preparing an elaborate meal, cooking demonstrates some basic ideas in chemistry. When you bake bread, you mix some flour, sugar, yeast, and water together. After baking, this mixture has been changed to form bread, another substance that has different characteristics and qualities from the original materials. The process of baking has produced chemical changes in the ingredients that result in bread being made.Most of the elements we know about do not exist freely in nature. Sodium cannot be found by itself (unless we prepare it in the laboratory) because it interacts easily with other materials. On the other hand, the element helium does not interact with other elements to any extent. We can isolate helium from natural gas during the process of drilling for oil.A chemical change produces different materials than the ones we started with. One aspect of the science of chemistry is the study of the changes that matter undergoes. If all we had were the elements and they did nothing, life would be very boring (in fact, life would not exist since the elements are what make up our bodies and sustain us). But the processes of change that take place when different chemicals are combined produce all the materials that we use daily.550542681537One type of chemical change (already mentioned) is when two elements combine to form a compound. Another type involves the breakdown of a compound to produce the elements that make it up. If we pass an electric current through bauxite (aluminum oxide, the raw material for aluminum metal), we get metallic aluminum as a product.? Electrolytic production of aluminum.Democritus (460 B.C.E.) and the Greek Philosophers548640145768Before we discuss the experiments and evidence that have convinced scientists matter is made up of atoms, it is only fair to credit the man who proposed the concept of the atom in the first place. About 2,500 years ago, early Greek philosophers believed the entire universe was a single, huge entity. In other words, “everything was one.” They believed that all objects, all matter, and all substances were connected as a single, big, unchangeable “thing.”Democritus was known as “The Laughing Philosopher.”One of the first people to propose the existence of atoms was a man known as Democritus, pictured above. He suggested an alternative theorywhere atomos – tiny, indivisible, solid objects – made up all matter in the universe. Democritus then reasoned that changes occur when the many atomos in an object were reconnected or recombined in different ways.Democritus even extended his theory to suggest that there were different varieties of atomos with different shapes, sizes, and masses. He thought, however, that shape, size, and mass were the only properties differentiating the types of atomos. According to Democritus, other characteristics, like color and taste, did not reflect properties of the atomos themselves but from the differentways in which the atomos were combined and connected to one another.6119177101073So how could the Greek philosophers have known that Democritus had a good idea with his theory of atomos? The best way would have been to take some careful observation and conduct a few experiments. Recall, however, that the early Greek philosophers tried to understand the nature of the world through reason and logic, not through experimentation and observation. The Greek philosophers truly believed that, above all else, our understanding of the world should rely on logic. In fact, they argued that the world couldn’t be understood using our senses at all because our senses could deceive us. Therefore, instead of relying on observation, Greekphilosophers tried to understand the world using their minds and, more specifically, the power of reason.Democritus’s version of the atomAs a result, the early Greek philosophers developed some very interesting ideas, but they felt no need to justify their ideas. Aristotle concluded men had more teeth than women did. He concluded this without ever checking in anyone's mouth because his conclusion was the “logical” one. As a result, the Greek philosophers missed or rejected a lot of discoveries because they never performed any experiments.Democritus’s theory would be one of these rejected theories. It would take over two millennia before the theory of atomos (or atoms, as they’re known today) was fully appreciated.Atomic TheoryLet’s consider a simple but important experiment that suggested matter might be made up of atoms. In the late 1700s and early 1800s, scientists began noticing that when certain substances, like hydrogen and oxygen, were combined to produce a new substance, the reactants (hydrogen and oxygen) always reacted in the same proportions by mass. In other words, if 1 gram of hydrogen reacted with 8 grams of oxygen, then 2 grams of hydrogen would react with 16 grams of oxygen, and 3 grams of hydrogen would react with 24 grams of oxygen.Strangely, the observation that hydrogen and oxygen always reacted in the “same proportions by mass” wasn’t unique to hydrogen and oxygen. In fact, it turned out that the reactants in every chemical reaction for a given compound react in the same proportions by mass. Take, for example, nitrogen and hydrogen, which can react to produce ammonia (NH3). In chemical reactions, 1 gram of hydrogen will reactwith 4.7 grams of nitrogen, and 2 grams of hydrogen will react with 9.4 grams of nitrogen. Can you guesshow much nitrogen would react with 3 grams of hydrogen?449516554328Scientists studied reaction after reaction, but every time the result was the same. The reactants always reacted in the same proportions by mass or in what we call “definite proportions,” as illustrated in figure to the right. As a result, scientists proposed the law of definite proportions. This law states that:In a given type of chemical substance, the elements always combine in the same proportions by massThe law of definite proportions applies when the elementsreacting together form the same product. Therefore, the law of definite proportions can be used to compare two experiments in which hydrogen and oxygen react to form water. The law, however, cannot be used to compare one experiment in which hydrogen and oxygen react to form water, H2O, with another experiment in which hydrogen and oxygen react to form hydrogen peroxide, H2O2, (peroxide is another material that can be made from hydrogen and oxygen).54864018214Dalton (1766-1844)A man named John Dalton, (to the left) discovered this limitation in the law of definite proportions in some of his experiments. Dalton was experimenting with several reactions in which the reactant elements formed different products, depending on the experimental conditions he used. One common reaction that he studied was the reaction between carbon and oxygen. When carbon and oxygen react, they produce two different substances – we’ll call these substances A and B. It turned out that, given the same amount of carbon, forming B always required exactly twice as much oxygen as forming A. In other words, if you could make A with 3 grams of carbon and 4 grams ofoxygen, B could be made with the same 3 grams of carbon but with 8 grams of oxygen instead. Dalton asked himself – why does B require twice as much oxygen as A does? Why not 1.21 times as much oxygen, or 0.95 times asmuch oxygen? Why a whole number, like 2?The situation became even stranger when Dalton tried similar experiments with different substances. For example, when he reacted nitrogen and oxygen, Dalton discovered that he could make three different substances – we’ll call them C, D, and E. As it turned out, for the same amount of nitrogen, D always required twice as much oxygen as C does. Similarly, E always required exactly four times as much oxygen as C does. Once again, Dalton noticed that small whole numbers (2 and 4) seemed to be the rule. Dalton used his experimental results to propose the law of multiple proportions:When two elements react to form more than one substance and the same amount of one element (like oxygen) is used in each substance, then the ratio of the masses used of the other element (like nitrogen) will be in small whole numbers.This law summarized Dalton's findings, but it did not explain why the ratio was a small whole number. Dalton thought about his law of multiple proportions and tried to develop a theory that would explain it. Dalton also knew about the law of definite proportions and the law of conservation of mass, so what he really wanted was a theory that explained all three laws with a simple, plausible model. One way to explain the relationships that Dalton and others had observed was to suggest that materials like nitrogen, carbon, and oxygen were composed of small, indivisible quantities, which Dalton called “atoms” (in reference to Democritus’s original idea). Dalton used this idea to generate what is now known as Dalton’s atomic theory.61191777059Dalton’s Atomic Theory:All elements are composed (made up) of atoms. It is impossible to divide or destroy an atom.All atoms of the same elements are alike. (One atom of oxygen is like another atom of oxygen.)Atoms of different elements are different. (An atom of oxygen is different from an atom of hydrogen.)Atoms of different elements combine to form a compound. These atoms have to be in definite whole number ratios. For example, waterDalton’s version of the atomis a compound made up of 2 atoms of hydrogen and 1 atom of oxygen (a ratio of 2:1). Three atoms of hydrogen and 2 atoms of oxygen cannot combine to make water.Dalton’s atomic theory explained a lot about matter, chemicals, and chemical reactions. Nevertheless, it wasn’t entirely accurate because, contrary to what Dalton believed, atoms can in fact be broken apart into smaller subunits or subatomic particles. Also, we now know that atoms of a given element have different masses, called isotopes (we will discuss later in the chapter). With Dalton’s Theory scientists were able to continue their research, later discovering the electron, proton, neutron and the structure of the atom.Eugene Goldstein (1886)4476750140450Eugen Goldstein, a German physicist, coined the term “cathode rays” for the negatively-charged particles that are emitted when an electric current if forced through a vacuum tube. He also discovered anode rays (also called canal rays), the positively-charged particles formed when the negative particles were removed from the gas particles in the cathode-ray tube. He showed that you can manipulate the rays with magnetic fields. His work suggested the presence of the proton, later discovered by Rutherford.549271112372J. J. Thomson (1906):J. J. Thompson was an English scientist. He discovered the electron when he was experimenting with gas discharge tubes. He noticed a movement in a tube. He called the movement cathode rays. The rays moved from the negative end of the tube to the positive end. He realized that the rays were made of negatively charged particles – electrons. Thompson’s model of the atom, which he called the plum-pudding model after the English dessert, showed the protons and electrons evenly distributed throughout the entire atom.Max Planck (1918):Max Planck was a German physicist who work with Einstein. Planck originated the Quantum Theory. Plank stated that electromagnetic energy would be omitted only in quantized form (a multiple of a unit). This is applied in chemistry to electrons; Planck’s theory lead to mathematically describe the probable location of electrons in an atom. His ideas lead to the thought that electrons can be found in different “levels” in an atom.Lord Ernest Rutherford (1911):5734046140064Ernest Rutherford conducted a famous experiment called the gold foil experiment. He used a thin sheet of gold foil. He also used special equipment to shoot alpha particles (positively charged particles) at the gold foil. Most particles passed straight through the foil like the foil was not there. Some particles went straight back or were deflected (went in another direction) as if they had hit something. The experiment shows:Atoms are made of a small positive nucleus; positive nucleus repels (pushes away) positive alpha particlesAtoms are mostly empty spaceNiels Bohr (Early 1913):54927534445Niels Bohr was a Danish physicist. He proposed a model of the atom that is similar to the model of the solar system. The electrons go around the nucleus like planets orbit around the sun. All electrons have their energy levels – a certain distance from the nucleus. Each energy level can hold a certain number of electrons. Level 1 can hold 2 electrons, Level 2 - 8 electrons, Level3 - 18 electrons, and level 4 – 32 electrons. The energy of electrons goes up from level 1 to other levels. When electrons release (lose) energy they go down a level. When electrons absorb (gain) energy, they go to a higher level.James Chadwick (1932):4425428125679James Chadwick was an English physicist who observed that when beryllium was bombarded with alpha (positively charged) particles, it emitted an unknown radiation that had approximately the same mass as a proton but with no electrical charge. Chadwick discovered the neutron.52273189229In a power outage all your electrical equipment suddenly stops working. The radio was on just a minute ago and now it is silent. What happened? Somewhere between a power generator and your radio there was an interruption. Power stopped flowing through the wires and into your radio. That “power” turns out to be electrons that move through the wires and cause an electrical current to flow.Is There Anything Inside an Atom?As the nineteenth century began to draw to a close, the concept of atoms was well-established. We could determine the mass of different atoms and had some good ideas about the atomic composition of many compounds. Dalton’s atomic theory held that atoms were indivisible, so scientists did not ask questions about what was inside the atom – it was solid and could not be broken down further. But then things began to change.The ElectronIn 1897, English physicist J.J. Thomson (1856-1940) experimented with a device called a cathode ray tube, the figure below, in which an electric current was passed through gases at low pressure. A cathode ray tube consists of a sealed glass tube fitted at both ends with metal disks called electrodes. The electrodes were then connected to a source of electricity. One electrode, called the anode, becomes positively charged while the other electrode, called the cathode, becomes negatively charged. A glowing beam (the cathode ray) traveled from the cathode to the anode.4583429-1856In order to determine if the cathode ray consisted of charged particles, Thomson used magnets and charged plates to deflect the cathode ray. He observed that cathode rays were deflected by a magnetic field in the same manner as a wire carrying an electric current, which was known to be negatively charged. In addition, the cathode ray was deflected away from a negativelycharged metal plate and towards a positively charged plate.54102065225Thomson knew that opposite charges attract one another, while like charges repel one another. Together, the results of the cathode ray tube experiments showed that cathode rays are actually streams of tiny negatively charged particles moving at very high speeds. While Thomson originally called these particles corpuscles, they were later named electrons. He concluded that electrons were negatively charged subatomic particles present in atoms of all elements.Electrons play a major role in bonding. As a result, they are attracted to positive objects and repelled from negative objects, including other electrons (left). To minimize repulsion,each electron is capable of staking out a “territory” and “defending” itself from other electrons.Protons458787573319Describing what we can see is a fairly easy matter. If we are asked to describe the sports car illustrated above, we could all quickly come up with a fairly accurate description. A person knowledgeable about cars would include more details, but everyone would have the basic information in their description.What makes the description easy to come up with? We can see it, we have a common language to describe it (size, color, construction), and we have a basic idea of what it is (a car, not a house or a tree). Scientists have far more difficulty in describing things they cannotsee. There is no way to look directly at an atom to see its detailed structure. When we first make a discovery, there is often no language to use to tell others exactly what it is. This was the problem in talking about the atom and its make-up.Putting the Puzzle Pieces TogetherResearch builds upon itself – one piece connects to another. Sometimes the puzzle doesn’t seem to make sense because some of the pieces are missing at the moment. Each finding gives a clearer picture of the whole and also raises new questions. The detective work that led to the discovery of the proton was built upon finding pieces to the puzzle and putting them together in the right way.The electron was discovered using a cathode ray tube. An electric current was passed from the cathode (the negative pole) to the anode (positive pole). Several experiments showed that particles were emitted at the cathode and that these particles had a negative charge. These experiments demonstrated the presence of electrons.If cathode rays are electrons that are given off by the metal atoms of the cathode, then what remains of the atoms that have lost those electrons? We know several basic things about electrical charges. They are carried by particles of matter and exist as whole-number multiples of a single basic unit. Atoms have no overall electrical charge, meaning that each and every atom contains an exactly equal number of positively and negatively charged particles. A hydrogen atom is the simplest kind of atom with only one electron. When that electron is removed, a positively charged particle should remain.Discovery of the ProtonIn 1886 Eugene Goldstein (1850-1930) discovered evidence for the existence of this positively charged particle. Using a cathode ray tube with holes in the cathode, he noticed that there were rays traveling in the opposite direction from the cathode rays. He called these canal rays and showed that they were composed of positively charged particles. The proton is the positively charged subatomic particle present in all atoms, so they are attracted to negative objects and repelled from positive objects. Again, this means that protons repel each other (illustrated below). However, unlike electrons, protons are forced to group together into one big clump, even though they repel each other. Protons are bound together by what are termed strong nuclear forces.These forces are responsible for binding the atomic nuclei together, allowing the protons to form a dense, positively charged center.The NucleusThe way Rutherford discovered the atomic nucleus is a good example of the role of creativity in science. His quest actually began in 1899 when he discovered that some elements give off positively charged particles that can penetrate just about anything. He called these particles alpha (α) particles (we now know they were helium nuclei). Like all good scientists, Rutherford was curious. He wondered how he could use alpha particles to learn about the structure of the atom.He decided to aim a beam of alpha particles at a sheet of very thin gold foil. He chose gold because it can be pounded into sheets that are only 0.00004 cm thick. Surrounding the sheet of gold foil, he placed a screen that glowed when alpha particles struck it. It would be used to detect the alpha particles after they passed through the foil. A small slit in the screen allowed the beam of alpha particles to reach the foil from the particle emitter. You can see the setup for Rutherford’s experiment in the figure below.2243137179507Assuming a plum pudding model of the atom, Rutherford predicted that the areas of positive charge in the gold atoms would deflect, or bend, the path of all the alpha particles as they passed through. You can see what really happened in the figure above. Most of the alpha particles passed straight through the gold foil as though it wasn’t there. The particles seemed to be passing through empty space. Only a few of the alpha particles were deflected from their straight path, as Rutherford had predicted. Surprisingly, a tiny percentage of the particles bounced back from the foil like a basketball bouncing off a backboard!The Nucleus Takes Center StageRutherford made the same inferences. He concluded that all of the positive charge and virtually all of the mass of an atom are concentrated in one tiny area and the rest of the atom is mostly empty space. Rutherford called the area of concentrated positive charge the nucleus. He predicted—and soon discovered—that the nucleus contains positively charged particles, which he named protons. Rutherford also predicted the existence of neutral nuclear particles called neutrons, but he failed to find them. However, his student James Chadwick discovered them several years later.NeutronsThe most famous detective in literature and history never existed. Sherlock Holmes was the creation of the British author Sir Arthur Conan Doyle. This mythical person had capabilities far beyond those of mere mortals. Holmes was capable of spotting the tiniest clue, the smallest piece of evidence to solve the crime. He could link all sorts of seemingly irrelevant data into a coherent whole to clear up whatever mystery he was dealing with.579755-1164058The Quest for the NeutronClues are generally considered to involve the presence of something – a footprint, a piece of fabric, a bloodstain, something tangible that we can measure directly. The discoveries of the electron and the proton were accomplished by those kinds of clues. Cathode ray tube experiments showed both the electrons emitted by thecathode with their negative charge that could be measured and the proton (also emitted by the cathode) with its positive charge. The neutron initially was found not by a direct observation, but by noting what was not found.Research had shown the properties of the electron and the proton. Scientists learned that approximately 1837 electrons weighted the same as one proton. There was evidence to suggest that electrons went around the heavy nucleus composed of protons. Charge was balanced with equal numbers of electrons and protons making up an electrically neutral atom. But there was a problem with this model – the atomic number (number of protons) did not match the atomic weight. In fact, the atomic number was usually about half the atomic weight. Therefore, something else must be present. That something must weigh about the same as a proton, but could not have a charge – this new particle had to be electrically neutral.In 1920 Ernest Rutherford tried to explain this phenomenon. Rutherford proposed the existence of a neutral particle along with the approximate mass of a proton, but it wasn't until years later that someone proved the existence of the neutron. A physicist named James Chadwick observed that when beryllium was bombarded with alpha particles, it emitted an unknown radiation that had approximately the same mass as a proton, but the radiation had no electrical charge. Chadwick was able to prove that these beryllium emissions contained a neutral particle – Rutherford’s neutron. This became known as the third subatomic particle or the neutron.6292850-23439As you might have already guessed from its name, the neutron is neutral. In other words, it has no charge and is therefore neither attracted to nor repelled from other objects. Neutrons are in every atom (with one exception), and they’re bound together with other neutrons and protons in the atomic nucleus. Again, the binding forces that help to keep neutrons fastened into the nucleus are known as strong nuclear forces.6445250212672Since neutrons are neither attracted to nor repelled from objects, they don’t interact with protons or electrons beyond being bound into the nucleus with the protons. Protons andelectrons, however, do interact. Using what you know about protons and electrons, what do you think will happen when an electron approaches a proton? Will the two subatomic particles be attracted to each other or repelled from each other? Here’s a hint: “opposites attract, likes repel.” Since electrons and protons have opposite charges (one negative, the other positive), you’d expect them to be attracted to each other, as illustrated below.4101465223058Mass of Subatomic ParticlesEven though electrons, protons, and neutrons are all types of subatomic particles, they are not all the same size. When comparing the masses of electrons, protons, and neutrons, you will find that electrons have an extremely small mass compared to the masses of either protons or neutrons, just like the mass of a penny so extremely small compared to the mass of a bowling ball. On the other hand, the masses of protons and neutrons are fairly similar, with the mass of a neutron being slightly greater than the mass of a proton. Because protons and neutrons are so much more massive than electrons, almost all of the atomic mass in any atom comes from thenucleus, which is where all of the neutrons and protons are located.The table below, gives the properties and locations of electrons, protons, and neutrons. The third column shows the masses of the three subatomic particles in grams. The second column, however, shows the masses of the three subatomic particles in amu, or atomic mass units. An atomic mass unit (amu) is defined as one-twelfth the mass of a carbon-12 atom (a carbon that has 6 protons and 6 neutrons). Atomic mass units are useful because, as you can see, the mass of a proton and the mass of a neutron are almost exactly 1.0 in this unit system.Subatomic Particles, Properties, and LocationParticleRelative Mass(amu)electro nElectric ChargeLocationoutside nucleusproton nucleus2612389179398neutro n nucleusIn addition to mass, another important property of subatomic particles is the charge. The fourth column in the table above shows the charges of the three subatomic particles. You already know that neutrons are neutral and thus have no charge at all. Therefore, we say that neutrons have a charge of zero. What about electrons and protons? Electrons are negatively charged and protons are positively charged, but the positive charge on a proton is exactly equal in magnitude (magnitude means “absolute value”) to the negative charge on an electron. In other words, a neutral atom must have exactly one electron for every proton. If a neutral atom has 1 proton, it must have 1 electron. If a neutral atom has 2 protons, it must have 2 electrons. If a neutral atom has 10 protons, it must have 10 electrons. Do you get the idea?Elemental SymbolThere are currently over 115 known elements. These elements vary widely in their abundance. For example, only five elements; oxygen, silicon, aluminum, iron and calcium, account for over 90% of the Earth’s crust.Similarly, three elements, oxygen, carbon, and hydrogen male up over 90% of the human body.In order to make chemistry easier for you, scientist gave each element a symbol. The element symbol consists of 1 or 2 letters, with the first letter always being a capital letter. The symbols are mostly derived from their English name for the element but there are a few elements whose symbol is derived from their Greek or Latin name.The table below shows common elements and their symbol.Atomic NumberScientists can distinguish between different elements by counting the number of protons. If an atom has only one proton, we know it’s an atom of the element hydrogen. An atom with two protons is always an atom of the element helium. When scientists count four protons in an atom, they know it’s a beryllium atom. An atom with three protons is a lithium atom, an atom with five protons is a boron atom, an atom with six protons is a carbon atom… the list goes on.452945440093Since an atom of one element can be distinguished from an atom of another element by the number of protons in the nucleus, scientists are always interested in this number and how this number differs between different elements. Therefore, scientists give this number a special name and a special symbol. An element’s atomic number is equal to the number of protons in the nuclei of any of its atoms. The periodic table gives the atomic number of each element. The atomic number is a whole number usually written above the chemical symbol of each element in the table. The atomic number for hydrogen is 1 because every hydrogen atom has 1proton. The atomic number for helium is 2because every helium atom has 2 protons. What is the atomic number of carbon? (Answer: Carbon has 6 protons, so the atomic number for carbon is 6.)Since neutral atoms have to have one electron for every proton, an element’s atomic number also tells you how many electrons are in a neutral atom of that element. For example, hydrogen has atomic number of 1. This means that an atom of hydrogen has one proton and, if it’s neutral, one electron. Gold, on the other hand, has atomic number of 79, which means that a neutral atom of gold has 79 protons and 79 electrons.Mass NumberThe mass number of an atom is the total number of protons and neutrons in its nucleus. Why do you think that the mass number includes protons and neutrons, but not electrons? You know that most of the mass of an atom is concentrated in its nucleus and that the mass of an electron is very, very small compared to the mass of either a proton or a neutron (like the mass of a penny compared to the mass of a bowling ball). By counting the number of protons and neutrons, scientists will have a very close approximation of the total mass of an atom.mass number = (number of protons) + (number of neutrons)An atom’s mass number is very easy to calculate once you know the number of protons and neutrons in the atom. Notice that the mass number is not the same as the mass of the atom. You can easily relate the mass number to the mass by recalling that both protons and neutrons have a relative mass of 1 amu.Example 1:What is the mass number of an atom that contains 3 protons and 4 neutrons?(number of protons) = 3 (number of neutrons) = 4mass number = (number of protons) + (number of neutrons)mass number = (3) + (4) = 7The periodic table of elements provides you with two values; the atomic number (protons) and the atomic mass (average mass of an element based on the abundance of each of its isotopes). The periodic table does not tell you the number of neutrons that exist in the most abundant isotope. To calculate the number of neutrons you subtract the atomic number from the atomic mass (rounded to the nearest whole number).5196888-15848How does the Periodic Table fit into this?The periodic table gives the atomic mass of each element. The atomic mass is a number that usually appears below the element’s symbol in each square. The mass number for boron is 5; this The atomic mass of boron (symbol B) is 10.8. To determine the number of neutrons we round 10.8 to 11 and subtract the atomic number (5) and get 6; therefore, boron has 6 neutrons.Take time to notice that not all periodic tables have the atomic number above the element’s symbol and the atomic mass below it. If you are ever confused, remember that the atomic number should always be the smaller of the two and will be a whole number, while the atomic mass should always be the larger of the two. (The atomic mass must include both the number of protons and the average number of neutrons.) The mass number is NOT included on the periodic table.3971925405768IsotopesAre all the members of the football team shown above identical?They are on the same team and are all known by the same team name, but there are individual differences among the players. We do not expect the kicker to be as big as the quarterback. The tight end is very likely to weigh less than the defensive tackle on the other side of the ball. They play as a unit, but they have different weights and heights.IsotopesThe history of the atom is full of some of these differences. Although John Dalton stated in his atomic theory of 1804 that all atoms of an element are identical, the discovery of the neutron began to show that this assumption was not correct. The study of radioactive materials (elements that spontaneously give off particles to form new elements) by Frederick Soddy (1877-1956) gave important clues about the internal structure of atoms. His work showed that some substances with different radioactive properties and different atomic weights were in fact the same element. He coined theterm isotope from the Greek roots isos (“equal”) and topos (“place”) and described them as “Put colloquially, their atoms have identical outsides but different insides.” Soddy won the Nobel Prize in Chemistry in 9121 for his work.Unlike the number of protons, which is always the same for all atoms of the same element, the number of neutrons can be different. Atoms of the same element with different numbers of neutrons are known as isotopes. Since the isotopes of any given element all contain the same number of protons, they have the same atomic number. However, since the isotopes of a given element contain different numbers of neutrons, different isotopes have different mass numbers. The following two examples should help to clarify this point.Example 2:What is the atomic number and the mass number of an isotope of lithium containing 3 neutrons and 3 protons in its nucleus?atomic number = number of protons = 3 number of neutrons = 3mass number = (number of protons) + (number of neutrons) mass number = (3) + (3) = 6In nature, only certain isotopes exist. For instance, lithium exists as an isotope with 3 neutrons and as an isotope with 4 neutrons, but it doesn’t exists as an isotope with 2 neutrons or as an isotope with 5 neutrons.This whole discussion of isotopes brings us back to Dalton’s atomic theory. According to Dalton, atoms of a given element are identical. But if atoms of a given element can have different numbers of neutrons, then they can have different masses as well. How did Dalton miss this? It turns out that elements found in nature exist as uniform mixtures with a constant ratio of their naturally occurring isotopes. In other words, a piece of lithium always contains both types of naturally occurring lithium (the type with 3 neutrons and the type with 4 neutrons). Moreover, it always contains the two in the same relative amounts (or “relative abundances”). In a chunk of lithium, 93% will always be lithium with 4 neutrons, while the remaining 7% will always be lithium with 3 neutrons.Unfortunately, Dalton always experimented with large chunks of an element – chunks that contained all of the naturally occurring isotopes of that element. As a result, when he performed his measurements, he was actually observing the averaged properties of all the different isotopes in the sample. Luckily, aside from having different masses, most other properties of different isotopes are similar. Chemical behavior is governed by the number of electrons and the number of protons. Carbon-13 behaves chemically in exactly the same way as the more plentiful carbon-12.Metrics (Measurement)Summer 2018 AssignmentHonors ChemistryWorking with SI (metric) UnitsFor each of the following commonly used measurements, indicate its symbol. Use the symbols to complete the following sentences with the most appropriate unit. litercentimetergrammilligram milliliterkilometerkilogramsecond metermillimetercentigrammillisecondThe mass of a bowling ball is 7.25 .The lung capacity of an average man is about 4.8 .The length of a housefly is about 1 .The average length of time it takes to blink is about 2 .One teaspoon of cough syrup has a volume of 5 .The length of a human’s small intestine is about 6.25 .The mass of a paperclip is about 1 .When resting, the average adult’s heart beats once every 1.2 .The mass of a flea is about 0.5 .The distance between San Antonio and Dallas is approximately 440 .Write the abbreviation for the following common metric prefixes:Kilo Hecto Deca/Deka Meter Gram Liter Deci Centi Milli Metrics (Measurement)Summer 2018 AssignmentHonors Chemistry980790173971Dimensional AnalysisConvert the following1. 35 daL = dL 2. 950 g = kg 3. 275 mm = cm 4. 1,000 L =kL 5. 1,000 mLL 6. 0.17 cm = hm 7. 2.65 km = dm8. 1.0 km =mm9. 18 dag =cg 10. 4,500 mgg25 cm = mm 12. 0.005 kg = dag 13. 0.075 m =cm14. 15 g = mg 15. 0.987 kL =hL 16. 1.281 mm =m 17. 12.07 hg = dag 18. 1625.0 cm = m 19. 3017.36 mg =dg 20. 71.18 L =cLWrite the number(s) given in each problem using scientific notation. Don’t forget the unit.The human eye blinks an average of 4,200,000 times a year. A computer processes a certain command in 15 nanoseconds. (A nanosecond is one billionth of a second.) In decimal form, this number is 0. 000 000 015 There are 60,000 miles (97,000 km) in blood vessels in the human body.miles kmThe highest temperature produced in a laboratory was 920,000,000 F (511,000,000 C) at the Tokomak FusionTest Reactor in Princeton, NJ, USA.oFoC5. The mass of a proton is 0.000 000 000 000 000 000 000 001 673 grams. 6. The mass of the sun is approximately 1,989,000,000,000,000,000,000,000,000,000,000 grams. The cosmos contains approximately 50,000,000,000 galaxies. A plant cell is approximately 0.00001276 meters wide. Write the number(s) given scientific notation in standard form. Don’t forget the unit.The age of earth is approximately 4.5 X 109years.The weight of one atomic mass unit (a.m.u.) is 1.66 x 10-27 kg.3740150-80008State the number of significant figures in each measurement. a. 734 grams b. 82.400 meters c. 92,000°C d. 0.003 second e. 607 liters f. 1 ? 10-4 hertzRound the number in the first column to the number of significant figures stated in each column.NumberFour significant figuresThree significant figuresTwo significant figuresOne significant figure84.6310.945007.953102,058,268Perform the following operations. Round the answers to the appropriate number of significant figures. Label.a.8.2 cm ? 6.08 cm ? 15.0 cmb. 34.8 meter / 3.048 secondsc.23.4°C – 8.4°Cd. 65.48 g + 3.0 g + 0.882 g + 26.46 gWrite the following numbers to 3 significant figures; round or convert to scientific notation if needed34,534 m0.2323 m3,004 m0.320 m4,000 m0.0033 m400.1 m0.0001 m300.0 m15.04 m30.00 m0.000004 mHonors ChemistryUnit: AtomsIsotopesName:Hour:Completed on Time (stamp) How were isotopes discovered?Define isotope.Here are three isotopes of an element:12C13C14CThe element is: The number 6 refers to the The numbers 12, 13, and 14 refer to the How many protons and neutrons are in the first isotope? How many protons and neutrons are in the second isotope? How many protons and neutrons are in the third isotope? Complete the following chart:Isotope nameatomic #mass ## of protons# of neutrons# of electronspotassium-37oxygen-17uranium-235uranium-238boron-10boron-115ElementsSummer 2018 AssignmentHonors Chemistry Please fill out the chart using the periodic table on the bottom of this paper. You will need to have all the information on the table memorized by the first day of school. Spelling counts ?Element NameSymbolAtomic Number(not the decimal number)Element NameSymbolAtomic Number (not the decimalnumber)AluminumLeadArgonLithiumBariumMagnesiumBerylliumMercuryBoronNeonBromineNickelCalciumNitrogenCarbonOxygenChlorinePhosphorousCopperPotassiumFluorineSiliconGoldSilverHeliumSodiumHydrogenSulfurIodineTinIronUraniumKryptonZinc974525170478Name:Hour: _ Completed on Time (stamp) Read the following information on elements, compounds and mixtures. Fill in the blanks where necessary.Elements:A pure substance containing only one kind of .An element is always uniform all the way through (homogeneous).An elementbe separated into simpler materials (except during nuclear reactions).Over 100 existing elements are listed and classified on the .Compounds:A pure substance containing two or more kinds of .The atoms arecombined in some way. Often times (but not always) they come together to form groups of atoms called molecules.A compound is always homogeneous (uniform).Compoundsbe separated by physical means. Separating a compound requires a chemical reaction.The properties of a compound are usually different than the properties of the elements it contains.Mixtures:Two or moreorNOT chemically combined.No reaction between substances.Mixtures can be uniform (called ) and are known as solutions.Mixtures can also be non-uniform (called ).Mixtures can be separated into their components by chemical or physical means.The properties of a mixture are similar to the properties of its components.Matter that is composed of only one kind of atom is classified as a(n) .What are pure substances? How are pure substances and mixtures different? What is the difference between an element and a compound?What is the difference between a compound and a mixture?Jewelry gold usually varies from 10K (10/24 gold) to 18K (18/24 gold) with other metals such as silver or platinum. Is jewelry gold an element, compound or mixture? Justify your answer.Match each diagram with its correct description. Diagrams will be used once.ABCDE 22. Pure Element – only one type of atom present. 23. Mixture of two elements – two types of uncombined atoms present. 24. Pure compound – only one type of compound present. 25. Mixture of two compounds – two types of compounds present. 26. Mixture of a compound and an element.Classify each of the following as elements (E), compounds (C) or Mixtures (M). Write the letter X if it is none of these. Diamond(C) Gasoline Electricity Krypton (Kr) Sugar (C6H12O6) Fire Water (H2O) Pail of Garbage Milk Uranium (U) Hotdog BakingSoda(NaHCO3) Iron (Fe) Boron (B) Salt (NaCl) Bronze (Cu & Sn) Air Alcohol (CH3OH) Energy Ink Sulfuric Acid (H2SO4) Ammonia (NH3) Gold Wood Dry Ice (CO2) Titanium (Ti) Concrete PizzaName:Hour:Completed on Time (stamp) Define matter. Define extensive property. Define intensive property. Define physical property. What is a chemical property? Define reactivity. Describe the relationship between metal’s location on the periodic table and it reactivity. Define flammability. What is the difference between a physical property and a chemical property of a substance? How can you use your knowledge of physical and chemical properties to identify an unknown substance?Changes of state (phase) are considered physical changes because What four signs indicate that a chemical change has taken place?Describe why the chopping wood is a physical change & burning wood is a chemical change. Be sure to use fancy chemistry terms.What change could be both physical and chemical?Place a checkmark or X in the appropriate column:ChangePhysicalChemicalSalt dissolves in waterHydrochloric acid reacts with magnesium to produce hydrogen gasA piece of copper is cut in halfA sugar cube is ground upWater is heated and changed to steamIron rustsEthyl alcohol evaporatesIce meltsMilk sours (goes bad)Sugar dissolves in waterGrass grows on a lawnA tire is inflated with airFood is digested in the stomachWater is absorbed by a paper towelPaper burnsWater freezes at 0°CFireworks explodeAlka-Seltzer gives off carbon dioxide when added to waterClouds form in the skyName:Hour:Completed on Time (stamp) A mixture (is/is not) a chemical combining of substances.In a compound the (atoms/molecules) are (chemically/physically) combined so that the elements that make up the compound (retain/lose) their identities and (do/do not) take on a new set of properties.The smallest identifiable unit of a compound is a (n) , which is made up ofwhich are chemically bonded.True or False: A mixture is always made up of a combination of elements or compounds.In a mixture, the substances (lose/retain) their identities.In a mixture the substances involved (can/cannot) be separated by a simple physical process. In a compound the elements involved (can/cannot) be separated by a simple physical process because the elements are (physically combined/chemically bonded).True or False: An element can be broken down into a simpler substance.The smallest identifiable unit of an element is a (n) .From the following list of substances, circle the ones that are elements:silvercarbon dioxidewoodalcoholwatersaltair hydrogencarbonnitrogenoxygengoldsugarsulfurClassify the following as pure substances or as mixtures:Air: Gasoline: Grain: Alcohol: Water: Sugar: Gold: Mercury: Oxygen: Salt water: Classify the following as heterogeneous or as homogeneous:sand & salt mixture: hydrogen: Iron: salt water: unfiltered air: iron with rust: pure water: an apple: nitric acid: tossed salad: Classify the following as an element, a compound, a solution, or a heterogeneous mixture:Aluminum: raisin bread: carbon dioxide: water: sugar and water: sulfur: sulfuric acid: mercury: an orange: water & instant coffee: a pencil: carbon particles & sugar: _nitrogen: air: gasoline: grain alcohol: Honors ChemistryUnit: MatterSeparation of a MixtureName:Hour:Completed on Time (stamp) Why would you need to separate a mixture?What is magnetism & when would you use it?What is chromatography & when would you use it?What is distillation & when would you use it?What is evaporation & when would you use it?What is filtration & why would you use it?What method(s) would you use to separate sugar & sand and why?What method(s) would you use to separate iron & sulfur and why?What method(s) would you use to separate ethanol & water and why?What method(s) would you use to separate steel and aluminum cans and why?What method(s) would you use to separate muddy water into sand & water and why?Name: _ _ Hour: _Date: _For each problem below, write the equation and show your work. Always use units and box or circle your final answer.The density of silver (Ag) is 10.5 g/cm3. Find the mass of Ag that occupies 965 cm3 of space.A 2.75 kg sample of a substance occupies a volume of 250.0 cm3. Find its density in g/cm3.Under certain conditions, oxygen gas (O2) has a density of 0.00134 g/mL. Find the volume occupied by 250.0 g of O2under the same conditions.Find the volume that 35.2 g of carbon tetrachloride (CCl4) will occupy if it has a density of 1.60 g/mL.The density of ethanol is 0.789 g/mL at 20oC. Find the mass of a sample of ethanol that has a volume of 150.0 mL at this temperature.30.0 g of each of the following acids are needed. Find the volume of each that must be measured out in a graduated cylinder.hydrochloric acid (HCl), density = 1.164 g/mLsulfuric acid (H2SO4), density = 1.834 g/mLnitric acid (HNO3), density = 1.251 g/mLA rectangular block of lead (Pb) measures 20.0 mm X 30.0 mm X 45.0 mm. If the density of Pb is 11.34 g/cm3, calculate the mass of the block.A cube of gold (Au) has a side length of 1.55 cm. If the sample is found to have a mass of 71.9 g, find the density of Au.An irregularly-shaped sample of aluminum (Al) is put on a balance and found to have a mass of 43.6 g. The student decides to use the water-displacement method to find the volume. The initial volume reading is 25.5 mL and, after the Al sample is added, the water level has risen to 41.7 mL. Find the density of the Al sample in g/cm3.(Remember: 1 mL = 1 cm3.)Name:Hour:Date: What is density? _ _ _ How are density and hardness different physical properties? _ _ _ _ _ _ _ _ What is the formula for density?What units are used for density?How are mL and cm3 related? _ _ _ _ _ _ _ _How is density used to determine if your car battery is good? _ _ _ _ _ _ _How is density used to identify substances? _ _ _ _ _ _ _ _What is an alloy? _ _ _ If a jeweler was trying to sell you a bracelet that he said was an alloy of 50% copper, how could you be sure he was correct?Name: Date:Hour: Scientists often express their uncertainty and error in measurement by giving a percent error. The percent error is defined as:% error =measured value ? actual value x 100 actual valueDefine accepted value.Define experimental value?While doing a lab, a student found the density of a piece of pure aluminum to be 2.85g/cm3. The accepted value for the density of aluminum is 2.70 g/cm3. What was the student's percent error?A student measured the specific heat of water to be 4.29 J/g · Co. The literature value of the specific heat of water is 4.18 J/g · Co. What was the student’s percent error?A student took a calibrated 200.0 gram mass, weighed it on a laboratory balance, and found it read 196.5 g. What was the student’s percent error?An object has a mass of 35.0 grams. On Anthony’s balance, it weighs 34.85 grams. What is the percent error of his balance?The density of water at 4oC is known to be 1.00 g/mL. Kayla experimentally found the density of water to be1.075 g/mL. What is her percent error?The Handbook of Chemistry and Physics lists the density of a certain liquid to be 0.7988 g/mL. Taylor experimentally finds this liquid to have a density of 0.7925 g/mL. The teacher allows up to +/- 0.500% error to make an “A” on the lab. Did Fred make an “A”? Prove your answer. ................
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