8th GRADE PHYSICAL SCIENCE: 2ND SEMESTER FINAL EXAM …



8th GRADE PHYSICAL SCIENCE: 2ND SEMESTER FINAL EXAM OUTLINE

SOUND

What type of wave is sound? Longitudinal wave

Infrasonic: frequencies lower than 20Hz

Ultrasonic: frequencies higher than 20,000 Hz

Doppler Effect: is the apparent change in the frequency of a sound

caused by the motion of either the listener or the source

of the sound.

Loudness: is how loud or soft sound is perceived to be and is measured in

Unit? Decibels

Resonance: occurs when an object vibrating at or near a resonant frequency

of a second object causes the second object to vibrate.

Interference: is the result of two or more waves overlapping.

Two types of interferences? Constructive and destructive

Sonar: using echoes to locate objects underwater and underground

LIGHT

Light is an electromagnetic wave.

Draw, label and give one example for each section of the electromagnetic spectrum:

Visible light spectrum

Reflection: occurs when light or any other wave bounces off an object.

Refraction: the bending of a wave as it passes at an angle from one medium

to another.

Diffraction: the bending of waves around barriers or through openings.

A convex lens makes images appear - larger

A concave lens makes images appear - smaller

CHEMICAL & PHYSICAL PROPERTIES/CHANGES

Physical property:

Matter can be observed or measured without changing the identity of the matter.

Example: color, state, odor, volume, mass

Chemical property:

Describe a substance based on its ability to change into a new substance with different properties. Example: flammable, reacts with oxygen

Physical change:

Change that affects one or more physical properties. It maintains its original self.

Example: breaking chalk, freezing water, cutting your hair

Chemical change:

Occurs when one or more substances are changed into entirely new substances with different properties.

Example: baking a cake, soured milk

THERMAL ENERGY

Temperature: measure of the average kinetic energy of the particles of

an object.

relationship between temperature and how fast the particles of an object are moving – THE FASTER THE PARTICLES OF AN OBJECT ARE MOVING, THE HIGHER THE TEMPERATURE OF THE OBJECT.

Thermal expansion: increase in the volume of a substance due to an

increase in temperature.

Kelvin: the official SI unit of temperature

Absolute zero: the lowest temperature on the Kelvin scale – 0 Kelvin

Heat: the transfer of energy between objects that are different

temperatures

Thermal equilibrium: energy is transferred from the higher

temperature object to the lower temperature

object until both objects reach the same

temperature.

Conduction: transfer of the thermal energy from one substance to another

through direct contact.

Example: spoon touching bowl of soup & getting hot

Conductor: substances that conduct thermal energy very well.

Example: iron skillet

Insulator: substances that do not conduct thermal energy very well.

Example: flannel shirt

Convection: the transfer of thermal energy by the movement of a liquid or

gas.

Example: one heater located in deep end of pool warms entire

swimming pool

Radiation: the transfer of energy through matter or space as waves.

Example: sunlight shines directly through window

Thermal conductivity: conducts thermal energy well

Specific heat capacity: the amount of energy it takes to raise the

temperature of 1 kg of the material 1 Kelvin

Page 256 to answer – specific heat:

List the 3 substances that heat the fastest: lead, gold and mercury

Does copper or aluminum heat the slowest? Aluminum 899

Because copper is 387

THE ATOM

Which takes up more space in an atom? Empty space

Protons: positively charged particles of the nucleus (+)

Neutrons: the particles of the nucleus that have no charge/neutral

Electrons: the negatively charged particles in atoms (-)

Quarks: the smaller particles that make up protons and neutrons

Nucleus: the tiny, extremely dense, positively charged region in the

center of an atom – made up of protons and neutrons

Electron energy levels: any of several different regions in which electrons

travel about the nucleus.

maximum # of electrons on the first 3 energy levels:

1st - 2

2nd - 8

3rd - 18

Draw a Bohr diagram for an atom that has 11 electrons:

List the valence electrons for the Bohr model you drew: 1

Valence shell: the outermost energy level of an atom

Valence electrons: electrons in the valence shell

Atomic number: the number of protons in the nucleus of an atom

Mass number: the sum of the protons and neutrons in an atom

Isotope: atoms that have the same number of protons but have

different numbers of neutrons

FIND THE FOLLOWING:

MASS NUMBER - 11 11 3+

B

5

PROTONS – 5

NEUTONS – 6

ELECTRONS (WITH THE CHARGE) 2

ATOMIC SCIENTISTS

Give one fact about each atomic scientist:

John Dalton: all substances are made of atoms & elements combine

JJ Thomson: theory of “plum-pudding” models-small particles are

inside the atom.

Ernest Rutherford: there is a small positively charged nucleus &

atoms have mostly empty space

Neils Bohr: Electrons travel in definite paths

Schrodinger & Heisenberg: Electrons are found in electron clouds

PERIODIC TABLE

The Periodic Law: the law that states that the chemical and physical properties of elements are periodic functions of their atomic numbers

SECTIONS OF THE PERIODIC TABLE: (study table on page 304-305)

GROUPS - Vertical columns of elements (from top to bottom) on the

periodic table

i) name 1 element in group 16: sulfur

PERIODS - Horizontal row of elements (from left to right) on the periodic

table

i) name 1 element in period 4: calcium

METALS - found to the left of the zigzag line, solid at room temperature,

good conductors, shiny and malleable

i) name 1 element that is a metal: iron

NONMETALS - found to the right of the zigzag line, most gases at room

temperature, not malleable or shiny, poor conductors

i) name 1 element that is a nonmetal: carbon

METALLOIDS - also called semiconductors, found at the border of the

zigzag line, have properties of both metals and nonmetals

i) name 1 element that is a metalloid: boron

The name for Na is sodium

Mercury has an atomic mass of 200

The chemical symbol for gold is Au.

The current periodic table is arranged by atomic number

Draw dot diagrams for elements 1-10:

( ( ( ( ( ( ( ( ( ( (

H( He ( Li ( Be ( B ( C ( ( N ( ( O ( ( F ( ( Ne (

( (

What family is neon in? Noble Gases

One fact about the family? Their atoms have 8 electrons in their outer

valence shell

One element in the alkali metals: Lithium

ELEMENTS, COMPOUND & MIXTURES

Element: a pure substance that cannot be separated or broken down into

simpler substances by physical or chemical means.

Example: Carbon

Compound: is a pure substance composed of two or more elements that are

chemically combined.

Example: NaCl = Sodium + Chlorine = Sodium Chloride

Mixture: is a combination of two or more substances that are not

chemically combined

Example: pizza

How are elements and compounds similar? Each has its own physical properties such as boiling point, melting point, density and color

How are compounds and mixtures similar? 2 or more elements join together

CHEMICAL BONDS

Atoms bond by gaining, losing or sharing electrons.

If an atom has a positive charge, it has LOST electrons.

If it has a negative charge it has GAINED electrons.

Ionic bond: the force of attraction between oppositely charged ions.

Ions: charged particles that form during chemical changes when one or

more valence electrons transfer from one atom to another.

Covalent bond: the force of attraction between the nuclei of atoms and

the electrons SHARED BY THE ATOMS.

Molecule: a NEUTRAL group of atoms held together by covalent bonds

COMPOUNDS

Binary compounds: a combination of two elements

Give one example of using the criss-cross method to make a binary formula:

Fe 2+ O 3-

Equals: Fe3O2

CHEMICAL REACTIONS & EQUATIONS

How many atoms of each element are in the following chemical formula?

2H2SO4 = 4 hydrogen atoms, 2 sulfur atoms, and 8 oxygen atoms

Is the following equation balanced or unbalanced? (show work)

2KCl + 3O2 ----------- 2KClO3

potassium 2 2

chlorine 2 2

oxygen 6 6

= a balanced equation

b) 4 potassium, 4 chlorine, 12 oxygen

c) label the following:

i) subscript - the 2 after the O and the 3 after O

ii) coefficient – the 2 in front of K, the 3 in front of O and the 2 in

front of KClO

iii) reactants – potassium (K), chlorine (Cl) and oxygen (O)

iv) products – 2KClO3

Law of Conservation of Mass:

In a chemical reaction, no mass is lost or gained

a) How does a balanced equation illustrate this law?

Even though a chemical reaction has taken place, both sides of the equation retain the same number of atoms.

TYPES OF REACTIONS

Synthesis: a reaction in which two or more substances combine to form a

single compound

Decomposition: A reaction in which a single compound breaks down to

form two ore more simpler substances

Single Replacement: A reaction in which an element takes the place of

another element that is part of a compound.

Double Replacement: A reaction in which ions in two compounds switch

places.

Endothermic: A chemical reaction in which energy is absorbed.

Exothermic: A chemical reaction in which energy is released or

removed

ACIDS & BASES

Acid: any compound that increases the number of hydrogen ions which

dissolved in water (pH scale: 0 – 6.9)

a) example: lemon

Base: any compound that increases the number of hydroxide ions

when dissolved in water (pH scale: 7.1 – 14)

a) example: baking soda

Neutralization: a chemical reaction between an acid and a base. (PH scale: 7)

Indicator: an organic compound that changes color in an acid or base

a) give an example of one indicator and how it indicates an acid

or a base: red cabbage juice turns litmus paper pink or red if

an acid and blue/green or yellow if a base

pH Scale: A scale that ranges from 0 to 14 to determine pH.

ACIDS 0 – 6.9 NEUTRAL 7 BASES 7.1 - 14

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14

( ( ( ( ( ( ( ( ( ( ( ( ( ( ( (

stomach lemon coffee water baking bleach oven

acid juice (5) (7) soda (12) cleaner

(1) (3) (9) (13)

-----------------------

Wavelength Decreases

Frequency Increases

Radio Microwave Infrared Ultraviolet X-ray Gamma

Ray

AM/FM Microwave Light in restaurants Tanning X-ray machine for Nucleur

Oven keep food warm bed broken bones

(

2+ 3-

Fe O

2+ 3-

Fe O

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