A Chemical Orthodoxy – Schools, Science and Education



8CP: Atoms, elements, compounds and the periodic tableLesson 1: The Periodic TableI am learning about the structure of the periodic table so I can use it to make predictions about different elementsEverything that you see around you is made of atoms. This page, your table, the water in your bottle – the air around you: all made of atoms. There are many different types of atom, and we call each type an element. Scientists today know of 118 different types of atom – so 118 elements. For a long time, scientists have been trying to categorise the elements and put them into useful lists. The first scientists to do this just ordered them by their weight. They noticed that the different atoms each had a different mass and called this “atomic weight.” They then put the atoms in order of their atomic weight. For example, titanium had an atomic weight of 48, so in their list it came before iron, which had a weight of 56.AtomAtomic weightA19B3C25D80E12F44How many different types of atom are there?What do we call the different types of atom?How did the first scientists order the different elements?A scientist has six atoms as shown in the table. What order would the scientist put them in?Properties of elementsBefore we go back to the periodic table, we need to learn about properties, which we will do by considering metals and non-metals, which are two categories of element. Metals have many important uses in everyday life such as jewellery, cars, electrical wiring and saucepans. The reason why they are so useful is due to the properties which they have. Metals can conduct electricity, which means that electricity can flow through them. They are therefore often used to make wires and parts of electrical circuits. Metals are also able to conduct heat which is why they are used for saucepans. Metals are strong and tough, which makes them good for building materials, and this is because there are strong forces between the metal atoms that hold them together. Metals have high melting and boiling points because of the strong forces between the metal atoms, for example copper has a melting point of 1085°C and a boiling point of 2562°C. (The melting point of a substance is the temperature at which a solid changes into a liquid. The boiling points of a substance is the temperature at which a liquid changes into a gas.) Metals are also malleable which means they can be easily shaped and ductile which means they can be bent and stretched to form wires. In contrast, normally non-metals are poor conductors of electricity. Non-metals are often also poor conductors of heat and so can be said to be insulators. They also tend to have low melting and boiling points, for example, the melting point of oxygen is -218°C and its boiling point is -183°C, hence we find oxygen as a gas. Non-metals are often also weak and brittle.Examples of properties:PropertyWhat it meansElectrical conductor Allows electricity to flow through itElectrical insulatorDoes not allow electricity to flow through itHeat conductorAllows heat to flow through itHeat insulatorDoes not allow heat to flow through itMalleableEasy to bendBrittleShatters easilyStrongCan hold a lot of weightWeakCan’t hold a lot of weightDuctileEasy to stretchHigh melting/boiling pointDoesn’t melt/boil until it gets to a high temperature (solid at room temperature)Low melting/boiling pointMelts/boils at a low temperature (liquid or gas at room temperature)HardDifficult to scratchSoftEasy to scratchReactiveReacts easily with other substancesUnreactiveDoes not react easily with other substancesMagneticIt is attracted to magnetsTransparentAllows all light to be transmitted through itTranslucentAllows some light to be transmitted through itOpaqueAllows no light to be transmitted through itWhat is the definition of melting point?What is the definition of boiling point?In your book, list the common properties of metals and the common properties of non-metalsMetals are used to make wires because…Metals are used to make wires but…Metals are used to make saucepans because…Metals are used to make saucepans but…Why do metals have high melting and boiling points?What is meant by ductile?Why are non-metals referred to as insulators?Why do non-metals have low melting and boiling points?Why are non-metals weak?Mercury is a metal, but it is a liquid at room temperature. Explain why this is unusual. A student is making a bridge made of a metal. Which property is most important when making a bridge?We learnt about properties because it will help us to understand the work of a Russian scientist called Mendeleev who tried to order the elements differently. Your teacher will show you how he changed the order. At the end of his process, the main changes were:Elements put together in groups based on their propertiesElements moved out of the order of atomic weights to make sure they were in the right groupsGaps left for elements that had not yet been discovered (and made predictions about the undiscovered elements’ properties)The table was periodic: it had a repeating patternAt first, how did scientists order the elements?How did Mendeleev order the elements?Why did Mendeleev leave gaps in his periodic table?Three atoms, A, B and C are all in one group. A and B are both strong and hard. Predict the properties of C.The table below shows five imaginary elements with their properties:ElementAtomic weightConducts electricity?Is it strong?Melting pointA45YesYesHighB23NoYesHighC8NoNoLowD68YesYesHighPut the elements in the order that scientists before Mendeleev will have doneWhich elements would Mendeleev have put in a group together?Which elements are metals?Which elements would be good for building bridges?Electricians need gloves which stop them getting electric shocks. Which elements would be good to make these gloves out of?Element C is transparent. Why would it be a bad substance to make oven doors out of?The melting point of B is 680°C. What state is it at 500°C?Scientists since Mendeleev have constructed the periodic table based on new discoveries. The major changes are:Elements organised by atomic number (you will learn more about this later)Elements put into groups by propertiesMetals to the left of the zigzag line, non-metals to the rightVertical columns are called groupsHorizontal rows are called periodsAll elements discoveredEach element has a symbol (earlier lists did this too)Use “atomic mass” not “atomic weight”Look at your periodic table. What group is calcium in?Find the element with the atomic number 27Name two elements in group 2Why did Mendeleev leave gaps in his table?How did Mendeleev arrange the elements?What does periodic mean?Explain how the modern periodic table is periodic. Find two elements that are in group 4Find two elements that are in group 5On the periodic table, argon has an atomic mass of 40 and potassium has an atomic mass of 39. Which would the early scientists have put first in their lists? Explain your answer.Why does potassium come after argon in the modern periodic table?Lithium and sodium are in the same group because…Lithium and sodium are in the same group but…Outline the similarities and differences between the three lists of elements we have looked atLesson 2: The atomI am learning about the structure of the atom so I can understand their positions in the periodic tableAtoms are tiny particles that are made up of even smaller particles called protons, neutrons and electrons. The protons and neutrons are found in the centre of the atom in the nucleus and the electrons are found orbiting the nucleus in shells. Your teacher will draw an atom out for you. What is smaller, an atom or a proton?What is between the electrons?A student draws an atom and labels the centre “nucleus with electrons.” Explain why the student is wrong.What label should the student use?Which element is in group 4, period 5?Is vanadium a metal or a non-metal?What properties would you expect vanadium to have?A student has a sample of phosphorous. Will it be most similar to nitrogen, silicon or sulfur? Explain your answer. Challenge: in what way do you think that atoms could be different from each other?When looking at an element within the periodic table, you can see that there is a number above the chemical symbol. This is the relative atomic mass. The number underneath the chemical symbol is the atomic number. The atomic number tells you the number of protons in an atom. This is also the number of electrons in the atom. This is because atoms have no overall charge and therefore in an atom, there must be an equal number of protons and electrons. Protons are positively charged and electrons are negatively charged and therefore they cancel each other out in terms of charge. The relative atomic mass tells you the number of protons plus the number of neutrons in the atom. To work out the number of neutrons, you do atomic mass – atomic number. Your teacher will show you how to work out the numbers of protons, neutrons and electrons for sulphur, lithium and vanadium.Calculate the number of protons, neutrons and electrons for:IronOxygenTungstenGermaniumStrontiumXenon How many neutrons are in an atom of tungsten?Why do atoms have equal numbers of protons and electrons?Why do protons and electrons attract each other?In an atom, the number of electrons has to be the same as the number of protons. Why can an atom have different numbers of neutrons to the number or protons? Charge is a property of small particles that can be positive, negative or neutral. Protons are positively charged, electrons are negatively charged and neutrons are neutral in charge. Opposite charges attract. Like charges repel. Neutral charges neither attract nor repel. From memory, draw a diagram of an atom. Include as many labels as you can think of.Using your purple pen, go back in your notes and add more labels to your diagramA student puts a positive and negative charge close together. What happens?A student puts two positive charges close together. What happens?A student puts a neutral charge and a negative charge close together. What happens?A student puts two neutral charges together. What happens?A student puts a proton and an electron close together. What happens?A student puts a neutron and an electron close together. What happens?How many protons, neutrons and electrons are in:Three atoms of sodiumFive atoms of phosphorous83 atoms of mercuryElectrons are found orbiting the nucleus in electron shells. The first shell, which is closest to the nucleus holds 2 electrons. The 2nd, 3rd and 4th shell all hold 8 electrons. An electron configuration diagram shows us how the electrons are arranged. When drawing electron configuration diagrams, we draw electrons as crosses and we have to fill up inner shells first. Your teacher will show you how to draw hydrogen, lithium and chlorine. Draw an atom of:Beryllium NitrogenOxygenHeliumNeonSulphurAluminiumSiliconCarbon PotassiumCalciumWhat do you find within the nucleus of an atom?What charge do electrons have?What is meant by atomic number?What is the atomic number of carbon?How many protons does an atom of lithium have?What group and period are carbon, lithium, chlorine and indium in?Why are carbon and lithium not in the same group?Chlorine is a non-metal. What properties would you expect it to have?Lithium conducts electricity. What other properties would you expect it to have? How many electrons does an atom of aluminium have?A substance is made of just aluminium atoms. What word could you use to describe it?Another substance is made of aluminium atoms and oxygen atoms chemically bonded. What word could you use to describe it?A third substance is made of aluminium atoms and oxygen atoms but they aren’t chemically bonded. What word could you use to describe it?Why is there always an equal number of protons and electrons in an atom?How many electrons can the first shell of electrons hold?How many electrons can the 2nd, 3rd and 4th shell of electrons hold?What can the group in the periodic table tell you about electrons?What can the period in the periodic table tell you about electrons?Look at your diagram of aluminium that you drew earlier. Explain how you know by looking at it that aluminium is in group 3 and period 3. Why do electrons repel each other? Groups within the periodic table are the vertical columns – there are groups 1-7 plus group 0 and the transition metals. The group number tells you the number of electrons which you find in the outer shell. Periods within the periodic table are the horizontal rows – there are 7 periods. The period tells you the number of shells of electrons which are present. What does the group number tell you in terms of electrons?What does the period number tell you in terms of electrons?Draw a particle diagram for chlorine (gas)Draw a particle diagram for sodium (solid)What can potassium’s group and period tell you about its structure?What can chlorine’s group and period tell you about its structure?What can xenon’s group and period tell you about its structure?Lesson 3: Elements and compoundsI am learning how to identify elements and compoundsIf a substance is made of only one type of atom, it is called an element. The names of all known elements can be found within the periodic table. If a substance is made of two or more different atoms chemically bonded together it is called a compound. An example is carbon dioxide – made of one carbon atom and two oxygen atoms chemically bonded. Mixtures are formed from two or more different types of substance which are not chemically bonded together, with an example being sandy water. The sand and the water are different, but they are not chemically bonded. What are atoms made up of?What makes up the nucleus of an atom?What do you find orbiting the nucleus?What is an element?Where can you find all known elements?What is the difference between a compound and a mixture?Is magnesium oxide an element or a compound? A substance is made of three different types of atom. Is it an element or a compound?A substance is made of three of the same type of atom. Is it an element or a compound?What is the main difference between elements and compounds? What could elements and compounds have in common?What are the names of the three subatomic particles (the particles that make up atoms)? There are five sentences below. Some are true and some are false. For each one, say whether you think it is true or false, and if it is false explain how you know it is false.If you want to know the name of a compound, you should look it up on the periodic table A lump of iron is an example of an element Table salt is made of sodium and chlorine atoms joined by chemical bonds and is therefore a compound If you want to make an element you need to take different types of atom and chemically bond them A piece of tellurium is an example of a compound For each of the substances below, state whether it is an element, compound or mixture. WaterSalt and oilAmmoniaNitrogen CalciumMethane Sandy waterIce cubes in a glass of waterIce cubes in a glass of cokeCement (sand, water and gravel)Draw an atom berylliumExplain why it is in group 2, period 2Why is it in a group with magnesium?Is it a metal or a non-metal?What properties would you expect it to have?Looking back: the questions below will draw on your knowledge of the previous unit we studied about light:Metals tend to be opaque. What does this mean?When metals are polished, they can reflect light. Draw a ray diagram showing how a metal could reflect light.Draw a normal to the metal and label the angle of incidence and the angle of reflection. Glass is a non-metal that is normally transparent. Explain what this means.When light enters glass it is refracted. Draw a diagram to show what this means. Some glass is translucent, so only allows some light to be transmitted. What happens to the rest of the light?In-between the pupil and the retina is a transparent liquid. What is the function of the pupil and what is the function of the retina?Explain why some people are long or short sightedCopper carbonate is a green solid. Explain in terms of light why it is green.White light is passed through a red filter onto some copper carbonate. What colour does the copper carbonate appear?Draw a ray diagram for a person looking at some copper carbonate by the light of a torch. The torch the student used had a mass of 175g. What is its weight on Earth?Explain why torches are necessary at nightExplain why the nights are shorter in the winterIf it is winter in the northern hemisphere, what season is it in the southern hemisphere?Why is there a seasonal difference between the northern and southern hemisphere?Lesson 4: Chemical reactions and compound formationI am learning about how to use word equations to describe chemical reactionsA mixture is when you have two or more different types of atoms which are not chemically bonded together, which therefore means you can separate the different types of atom easily. In contrast, a compound is when you have two or more different types of atoms which are chemically bonded together, which therefore means you can’t separate them easily. The properties of individual elements do not change when they are mixed. However, when atoms of different elements are joined together chemically, they form a new substance (a compound). The properties of the compound are different from those of the individual elements that form it. Your teacher will demonstrate what happens when sodium reacts with chlorine gas. What was the appearance of sodium at the start of the reaction?What was the appearance of chlorine at the start of the reaction?Describe what you saw in the reactionHow can you tell that chlorine has a low melting point? How can you tell that chlorine is a non-metal?Sodium is a metal. What properties would you expect it to have?Sodium is soft and can be cut with a knife. Why would you have expected it to be hard?Sodium is in group 1. Why did Mendeleev put the elements in group 1 together?In Mendeleev’s periodic table, there were gaps between some of the elements. Why did he leave gaps?Sodium and chlorine react together to form sodium chloride. Which substances are elements and which are compounds?Sodium chloride is a white solid that is safe to eat. Explain why its properties are so different to the elements that make it up.The demonstration which you have seen involved sulphur (yellow powder) and iron filings. Sulphur is a non-metal and iron is a metal. Iron is one of three magnetic metals – iron, nickel and cobalt. It was clearly a mixture, as you could use the magnet to separate out the iron filings from the sulphur. 35625709979Practical work – heating a mixture of iron filings and sulphur powderUse your periodic table to find the symbols for iron and for sulfur.How many protons, neutrons and electrons are in iron and in sulfur?Why is the number of electrons equal to the number of protons in an atom of iron?Draw an atom of sulfur, showing all the electrons. Iron is magnetic. Sulfur is not. When they are mixed together they can be separated with a magnet. Explain why.When they have chemically bonded, you cannot separate them with a magnet. Explain why.Once a chemical reaction has taken place, a word equation to show what has happened may be written. The reactants are found on the left-hand side of the arrow and are what you started with. The products are found on the right-hand side of the arrow and are what you made during the reaction. Reactants ProductsMagnesium + oxygen Magnesium oxideWhen you are naming the compound which has been formed, the metal (if there is one) will always go first e.g. in the example above Magnesium is a metal. The second part of the compound will be the non-metal. If there are only 2 elements in the compound, the ending for the non-metal is shortened and changed to –plete the following word equations in your exercise bookLithium + oxygen Aluminium + oxygen Sodium + oxygen Iron + sulphur Copper + sulphur Calcium + chlorine Magnesium + bromine Lithium + fluorine What is the difference between a mixture and a compound?Which side of the arrow will the products go?Give 3 properties of metalsWhat is meant by boiling point? Draw a picture to show the difference between a compound, element and mixture (use different colours to help you show different types of atoms)Copper is a reddish metal. Oxygen is a colourless gas. When they react together they form copper oxide which is black.Write a word equation for this reactionIdentify the reactants and the productCopper conducts electricity, but copper oxide does not. Explain why. If a copper and an oxygen atom bond together, how many protons are there in total?A scientist discovers a new element, which is a solid at room temperature, conducts electricity and is malleable. Should the scientist put it in a group with copper or oxygen? Explain your answer. Lesson 5: Chemical formulaeI am learning how to use the chemical formula of a substance to identify the atoms that make it upChemical formula is the shorthand way of the names of elements and compounds. They are useful as they also tell you how many of each atom you have in the substance. You work out the chemical formula of a substance using symbols from the periodic table. When using the periodic table to write a formula, capital letters must always be used, unless there are two letters, in which case the second one is in lower case. For example, Aluminium is plete the table below:Name of compoundAtoms which it containsChemical formulaCarbon monoxide1 carbon and 1 oxygenCOCarbon dioxide1 carbon and 2 oxygensCO2Hydrogen chloride1 hydrogen and 1 chlorineSodium chloride1 sodium and 1 chlorine Methane1 carbon and 4 hydrogensMgOWater2 hydrogens and 1 oxygenLiBrKClCaO2 potassium and 1 oxygen2 aluminium and 3 oxygen Carbon dioxide is a non-metal with a very low boiling point. Would you expect it to be a solid, liquid or gas at room temperature?Explain your answer. Would you expect carbon dioxide to conduct electricity? A student says that carbon dioxide has two atoms of carbon and two atoms of oxygen in it. Use the table above to explain how you know they are wrong. What type of atoms are in vanadium pentoxide, V2O5? How many of each are there?The formula for potassium chloride is KCl, but the formula for magnesium chloride is MgCl2. List as many similarities and differences between the two substances as you can. The formula for sulfur is S8 and the formula of ethane is C2H6. Draw an atom of sulfur, an atom of carbon and an atom of hydrogenHow many protons and neutrons are there in each?What is the charge on a proton, neutron and electron?List as many similarities and differences between the two substances as you can. Lesson 6: Reactions and the conservation of massI am learning about how the conservation of mass explains how mass changes in a chemical reaction3444801816048The diagram below shows a chemical reaction:Substance P + substance Q substance RYou can see that elements have been combined to make a compound. But what you should also be able to see is that the atoms involved at the start are still there at the end. They haven’t disappeared – they have just been rearranged.Scientists used to think that atoms could be created or destroyed in chemical reactions. We now know this is not true. In fact, atoms aren’t created or destroyed in chemical reactions, they are just rearranged. We call this the law of conservation of mass, and you learned about it last year when we studied particles. Look at the diagram and answer the questions.Which substances are elements? Which substance is a compound?Identify the reactants and the productsIn terms of atoms and rearrangement, how can you tell that a chemical reaction has taken place?How many atoms of P are on the left?How many atoms of Q are on the left?How many atoms of P are on the right?How many atoms of Q are on the right?How do your answers prove that mass has been conserved in this reaction?You can also observe or feel if a chemical reaction has taken place. In a chemical reaction, energy is often released or taken in. This results in you being able to feel the temperature changing. You can often also see bubbling or fizzing, which are gases being produced. Sometimes there is a colour change too. Each of these are proofs that a chemical reaction has taken place. Your teacher will first demonstrate to you the combustion of hydrogen.What did you observe in the reaction?How did this prove there was a reaction? Hydrogen is a gas at room temperature. Draw a particle diagram for a gas.Hydrogen can be used to fill a balloon. What happens to the pressure inside the balloon if it is warmed up? Explain your answer. Hydrogen reacts with oxygen to make water. Write a word equation for this reaction. Your teacher will now demonstrate to you the reaction between copper and nitric acid. What did you observe in the reaction?In what ways could you tell a reaction was taking place?Watching the reaction, a student said that the copper was destroyed in the acid. Explain why this is incorrect.Copper is a metal. Name three likely properties of copper.Copper is an element but nitric acid is a compound. What is the main difference between copper and nitric acid?The formula for nitric acid is HNO3. Which atoms are in nitric acid and how many are there?The copper nitrate formed is a blue colour. What does this tell you about the light it absorbs and reflects? Why did we use transparent glass to put the acid in?Your teacher will now demonstrate to you the reaction between magnesium and oxygen. In this reaction the mass increases. At the start of the reaction, only the magnesium is being weighed. The oxygen is not weighed, because it is free in the air. As the reaction continues, the atoms of magnesium stay where they are, and atoms of oxygen bond to them. When it is weighed at the end, there are more atoms, so more mass, and the balance gives a higher reading. In a chemical reaction, the mass will increase if a gas is added. Write the word equation for the reaction that was carried outThe diagrams below show what is occurring during the reaction. White circles are atoms of oxygen, and grey ones are atoms of magnesium.-319087513652500Label two elements in the diagramsLabel a compound in the diagramsName all the elements and compoundsUse the number of particles to prove that mass has been conserved in this reactionUse the number of particles to explain why the mass of the product is greater than the mass of the initial magnesiumYour teacher will now mix copper sulfate and sodium hydroxide together, weighing the reactants and then the products to look at how the mass changes. What was the mass of copper sulfate used?What was the mass of sodium hydroxide used?What was the appearance of the two solutions?What did you observe when they were mixed together?How could you tell a chemical reaction had taken place?What was the mass of the two solutions mixed together?The two substances for copper hydroxide and sodium sulfate. Write a word equation for the reactionThe formula for copper hydroxide is CuOH. Which elements are in it and how many atoms from each?The formula for sodium sulfate is Na2SO4. Which elements are in it and how many atoms from each?Your teacher will now add marble powder to hydrochloric acid on top of a balance so you can see how the mass changes.How did the mass change during the reaction?What did you observe during the reaction?How did this prove that a reaction was taking place?Marble powder is called calcium carbonate. When it reacts with the hydrochloric acid, it forms calcium chloride, water and carbon dioxide. Write a word equation for this reaction.Identify all reactants and products.Use your table from lesson 5 to write down the formula of carbon dioxide and state how many atoms it has in it and what type they are.Calcium chloride is a white powder. Calcium is a grey metal and chlorine a green gas. Explain why calcium chloride can be a white powder when it is so different to the elements that make it up. When mass appears to be gained or lost, gases are involved. Gases can be produced as a product and would be escape, hence the mass observed would have decreased. Gases can be taken in as a reactant and would be transferred to the products, hence the mass observed would have increased. Therefore if the:Mass stays the same: no gases have been involvedMass increases: gas has been addedMass decreases:Gas has been producedThe sentences below explain why the mass of calcium carbonate decreases (goes down) when it is put in acid. Put the sentences in order and write out in your exercise book:You can see lots of fizzingThe gas escapes the flask into the airThe calcium carbonate is added to acidThere are now fewer atoms in the flask than there were beforeThis is because a gas, carbon dioxide, is being producedIn a reaction, magnesium is added to acid. It starts to fizz. What would you expect to happen to the mass?Explain your answer.A teacher adds magnesium to a flask and quickly puts a bung (a type of lid) in the flask. What would you expect to happen to the mass?Lesson 7: Physical changes and chemical reactionsI am learning about the key features of chemical reactions and physical changes so I can identify which one has taken placeRecap questions:What name is given for a solid turning into a liquid?What name is given for a liquid turning into a gas?What name is given for a gas turning into a liquid?What name is given for a liquid turning into a solid?If liquid water turns into steam, has a new substance been formed?If 100g of ice melts, what mass of liquid water is formed?If 100g of liquid water is boiled, what mass of steam is formed?A substance can either be a solid, liquid or gas. Substances can change between these different states of matter and their mass won’t change. Physical changes are different to chemical changes because there is no actual reaction taking place and no new substances are made. The particles stay the same, they just have a different arrangement and the amount of energy. If liquid water is heated to form a gas, it is still water – just as a gas. Therefore, if I boil 100g of water for ten minutes and then weigh it again, it will weigh less, because the steam has left and escaped. But if I could capture that steam (like by using a balloon) then the mass of the steam and the leftover water would be 100g. So in a physical change, no new substance is formed. It is the same substance, just in a different state. During a chemical change, there is a reaction taking place and new substances have been formed and the atoms have been rearranged. Decide which of the below are physical changes and which are chemical reactionsFrying an eggDissolving sugar into waterBurning magnesium in oxygenReacting iron and sulphur togetherMelting an ice cubePuddles drying upA candle burningMixing ribena and waterA student puts 30g of water in the freezer. It turns to ice. What mass will the ice be?Explain your answer.A student boils 30g of water in a cup, but stops whilst there is still liquid in the cup. Will the mass have increased, decreased or stayed the same? Explain your answer. In a chemical reaction, the mass is found to increase. What is most likely to have occurred? Lesson 8: Group 1I am learning about the trends in group 1 to make predictions about the properties of group 1 elementsGroup 1 are also called the alkali metals – this is because when they react with water, they form an alkaline solution. Group 1 metals are very reactive and so they are all stored in oil to prevent them from reacting with oxygen in the air. Their reactivity increases as you move down the group, so lithium is the least reactive metal and francium is the most reactive metal. All the alkali metals have a very low density for metals – so much so that lithium, sodium and potassium will all float on water. The alkali metals are also very soft, so they can be cut with a knife. They have the silvery, shiny look of typical metals when we first cut them. However, they quickly go dull as they react with oxygen to form a layer of oxide. The group 1 metals also melt and boil at relatively low temperatures. As you move down group 1, the melting and boiling points get lower and lower. When group 1 metals react with water, they form hydrogen which is a gas and also a metal hydroxide. For example:Lithium + water Lithium hydroxide + hydrogenWhat is meant by melting point?What is meant by boiling point?What is the trend (pattern) in melting and boiling points as you move down group 1?What is the trend in reactivity as you move down group 1?Draw the electronic configuration of sodiumHow many electrons are found in the outer shell of group 1?Why are group 1 also called the alkali metals?Why does lithium and potassium float on water?What precaution is taken when storing group 1 metals due to their reactivity?Why do group 1 metals quickly go dull once they are cut?Complete the equation: Sodium + water Complete the equation: Potassium + water Identify all elements and compounds in your equations aboveDraw an atom of sodium and an atom of potassium showing all electrons.What do they have in common? What is different about them?How many neutrons do they each have?1g of sodium is added to 10g of water. Would you expect the resulting solution to be more than, equal to or less than 11g? Explain your answer. If you look at sodium in the air, it is a dull colour because…If you look at sodium in the air, it is a dull colour but…If you look at sodium in the air, it is a dull colour therefore…Lesson 9: Group 7I am learning about the trends in group 1 to make predictions about the properties of group 1 elementsGroup 7 elements are called the Halogens. They are a group of toxic non-metals which all have coloured vapours. They are typical non-metals as they have low melting and boiling points and they are also poor conductors of heat and electricity. The boiling points increase as you go down the group.The halogens all look different. At room temperature, fluorine is a very reactive, poisonous, pale yellow gas, while chlorine is a reactive, poisonous, dense green gas. Chlorine has a very distinctive smell and it is used as a sterilising agent and hence it is used in swimming pools. Some of the physical properties of the halogens are given below:HalogenMelting point (°C)Boiling point (°C)Fluorine-220-188Chlorine-101-35Bromine-7+58Iodine+114+183Describe the trend in melting points of the halogensName the halogen that will be a liquid at room temperature (20°C)Predict the melting point of astatine. Use your periodic table to help you. What are group 1 also called?What are group 7 also called?What happens to the reactivity of group 1 as you go down the group?What happens to the reactivity of group 7 as you go down the group?How many electrons do group 7 have in their outer shell?A student says that Mendeleev put group 1 elements together because they have the same number of electrons in the outer shell. Explain why this is incorrect. What happens to the boiling point as you go group 7?What would the chemical formula be for lithium chloride?What would the chemical formula be for potassium bromide?What would the chemical formula be for sodium iodide?Draw the electronic configuration for chlorineRevision questionsWhat is an element?Why are Lithium, Sodium and Potassium all in group 1 of the periodic table?Give two properties that chlorine, fluorine and iodine have in commonWrite a word equation for the reaction of any of the group 1 metals with water. What happens to the reactivity of group 1 metals as you come down the group?Predict what you would see if caesium reacted with water. Name the products of the reaction (remember it is a group 1 element…).Some information about the elements in group 1 is given below:HalogenMelting point (°C)Boiling point (°C)Lithium1801342Sodium97883Potassium63759Rubidium39688Describe the trend in the boiling points of the group 1. Use data to back up your statements. Which metal shown would be a liquid at 50°C?Suggest a value for the melting point of Caesium. Complete the following sentence: “Some people think water is an element. They are wrong. In fact…”Explain why we keep the group 1 metals under oil in the chemical prep roomA piece of lithium reacts in 12 seconds. An identical piece of potassium reacts in 3 seconds. Calculate how many times faster the potassium reacts.A student puts 5g of sodium in a jar. She reacts it with chlorine to make sodium chloride. Will the sodium chloride weigh more, less or the same as 5g? Explain your answer. A student heats up a substance. The mass of the substance decreases. The student says that “the atoms from the substance have been destroyed.” Explain why the student is wrong.What could have happened instead to cause the mass to decrease? ................
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