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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