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8th Grade Physical Science SOL Review
Transcript of 8th Grade Physical Science SOL Review
8th Grade Physical Science: An Overview
Steps to convert metric units:
1. Locate your starting point on the metric conversion chart.
2. Locate your ending point.
3. Find the decimal in the number you are working with.
4. Decide how many times to move the decimal and in what direction.
5. Move the decimal, adding zeros when needed.
6. Write your new number, with the decimal in the correct place.
k h dk (Base Unit) d c m
1. 3 L = _______ mL
2. 5.5 L = ______ dL
Answer: 55 dL
3. 3,000 cm = ________m
Answer: 30 m
4. 3,700 g = ________ kg
Answer: 3.7 kg
5. 0.72 L = ________ mL
Answer: 720 mL
6. 350 hg = _______ g
7. 6 km = ___________ m
8. 80,000 cm = ___________ hm
9. 3,000 cg = _________ mg
10. 25.5 mm = ____________ cm
How molecules are arranged in each state:
The four states, and the transitions
anything that has mass and takes up space
all matter is made up of tiny particles, called atoms and molecules
matter cannot be CREATED or DESTROYED.
Elements are made up of one type of atom.
Atoms are made
of protons, neutrons,
make up the
the nucleus in different
This Greek philosopher
hypothesized that if you
kept cutting a piece of matter
in half again and again, eventually
you would get to the smallest
particle of matter possible.
He named this particle "atomos",
meaning "not to be cut".
John Dalton, the English scientist
did many experiments that supported
the idea the matter was made of atoms.
Thought the atom was a solid sphere that
could not be divided. His model looked like
J.J. Thomson discovered that
the atom was made of even
smaller particles. He discovered
a negative charge existing in a
neutral gas, and concluded that
the atom must have a negatively
charged particle inside.
His model of the atom is known as
the "Chocolate Chip Cookie" model.
He thought the atom was a positively
charged substance with negatively charged
electrons scattered throughout.
How do we know this?????
The work of these scientists brought us
to this conclusion.
Neils Bohr found that
electrons orbit in specific
energy levels around the nucleus. He compared the
motion of electrons to
planets in the solar system. His model looked like a target.
Electron Cloud Theory.
Today atomic theory states that
electrons don't follow a certain path
around the nucleus. Their exact location
cannot be pinpointed, and they travel at
near the speed of light.
The electrons with the lowest energy are closer
to the nucleus, while higher-energy electrons
are farther away.
Length Meter (m) Ruler, meterstick
Mass Gram (g) Balance
Density Grams per Formula: D = m/v
(g/mL or g/cm3)
Volume Liter (L) Graduated
Temperature Celsius (0C) Thermometer
Force Newtons (N) Spring scale
All known elements
can be found on the
Metals are good conductors of heat and electricity.
Metals are shiny.
Metals are ductile (can be stretched into thin wires).
Metals are malleable (can be pounded into thin sheets).
Non-metals are poor conductors of heat and electricity.
Non-metals are not ductile or malleable.
Solid non-metals are brittle and break easily.
They are dull.
Many non-metals are gases.
Metalloids (metal-like) have properties of both metals and non-metals.
They are solids that are shiny.
They conduct heat and electricity better than non-metals but not as well as metals.
They are brittle.
For the elements in group A,
the number of VALENCE electrons
(electrons in the outer shell) is the
number at the top of the column.
Elements can be classified
into metals, nonmetals,
There are 2 main types of bonds.
Compounds are formed when atoms combine chemically.
Ionic bonds occur between metals
Q: Why do atoms combine?
A: They need a certain number
of electrons in their outer shell
(valence electrons) in order to be
stable. To get those, they will
steal, share, or give away electrons
with other atoms. This creates a bond
between the atoms.
Ionic bonds occur when one atom takes electron(s) from another atom.
The atom that takes the electron becomes a negative ion. The atom that loses an electron becomes a positive ion.
Since negative and positive charges attract, this creates a bond between the two (or more) ions.
Covalent bonds occur between
two or more nonmetals.
Covalent bonds occur when
atoms share electrons.
They can share one or more electrons so that each atom has the desired 8 valence electrons.
The electrons spend some time around
one atom, and some time around the
other, creating a bond.
WHAT IS A COMPOUND?
COMPOUNDS CAN BE
A CHEMICAL FORMULA
Mixtures are made of 2 or more substances.
The substances are not chemically combined.
Also, the substances are not in
a set ratio, like they are in a
Ex. Water (a compound) is ALWAYS 2 parts
Hydrogen to one part Oxygen, but a mixture of lemonade can have different amounts of sugar,
lemon juice, etc, depending on how
a person likes to mix it.
If you add a little more sweetener, or a few more
lemons, it's STILL lemonade!
Special Types of Compounds......
Produce H+ ions in water.
pH is less than 7
Ex: lemon juice, vinegar, hydrochloric acid
Produce OH- ions in water
Taste bitter, chalky
Feel soapy, slippery
pH greater than 7
Ex. Soap, Maalox, Baking Soda
When an acid and a base mix, they
, or a create water and a salt.
contain the element
They make up the basic
chemicals for all living things.
Compounds (ionic or covalent)
that are NOT biological in nature.
You can identify a substance by its properties.
Characteristics that can be observed or
measured without changing the type of
matter. They describe the way an object looks.
State of matter
Luster - how shiny or dull a material is.
Conductivity - whether it conducts either heat or electricity.
Solubility - whether or not it dissolves in another substance, like water.
Characteristics that depend upon how a substance reacts or changes into another substance.
Corrosiveness - the ability to wear away a material (ex. acids are corrosive)
Reactivity to water
Reactivity to oxygen
Reactivity to acids
Reactivity to bases
Toxicity - how poisonous a substance is; how it reacts in the body.
is the energy stored in the nucleus of an atom.
What: When an atom's nucleus breaks apart,
Where: We use fission reactions to make electricity
in nuclear power plants.
What: Two nuclei combine
to make a larger nucleus, and
energy is released.
Where: Fusion is the most common form of energy in the universe -- it's what happens in the core of stars like our sun.
Potential Energy is
and waiting to be used.
Kinetic Energy is the energy of
the ability to do work.
energy is able to cause some kind of change in matter.
cannot be CREATED or DESTROYED
Energy can't be created or destroyed, but it CAN change form.
One example of this is our ability to make electricity from so many different sources: wind, water, coal, natural gas, nuclear, etc.
Ernest Rutherford did an
experiment where he shot
positively charged alpha particles through a thin sheet of gold foil.
Most of the particles went through the foil but some were repelled. He concluded that the atom was mostly made of empty space and had positively charged particles in the center.
His model looked like a peach with a positively charged nucleus, surrounded by electrons
Here is some information!!!!
Freezing point of water
Boiling point of water
This scale is based on the properties of water.
It is used in most countries and by scientists.
This scale is based on
zero is the point where matter would STOP moving.
How Heat Moves
Conduction - heat moves
from particle to particle
by direct contact.
Convection: hot gas
or liquids rise and then cool-circulate.
Radiation: waves of pure energy
that can travel through empty space.
We use heat to do work - to make things move, to cook food or heat homes.
We also have devices that remove heat from where we don't want it, like a refrigerator.
The kinetic theory states that:
* particles of matter are always in motion
(have kinetic energy).
*the faster those particles move, the greater
During a phase change,
the temperature of the
substance stays the same.
Light is a transverse wave!
Light is fast!
There are seven types of light, or radiant energy!
Light can do interesting things!
occurs when light changes its
medium (the substance it is traveling
through) and changes speed.
occurs when light bounces off a shiny surface
occurs when a wave passes through a barrier
and spreads out
light from 2 or more sources combines to
create an interference pattern
constructive - makes it brighter
destructive - makes it darker
Sound travels in longitudinal,
or compressional, waves.
The speed of sound depends on
the temperature of the substance
and the material it travels through.
Which substance has
the highest speed?
THERE IS NO SOUND IN SPACE!!!! SOUND MUST HAVE MATTER TO VIBRATE BACK AND FORTH.
Sound in Technology
We can use reflected sound waves to see things underwater or inside the body.
This occurs in nature, too.
Bats use echolocation to find
Aquatic animals use it to
"see" in the dark ocean.
One property of sound is
Each object vibrates at a
certain frequency depending
on what it is made of and
If an outside source can match
this frequency, it can amplify
it to the point where it could break!
A substance at a higher temperature will have more heat.
Ex. Water that is boiling has more heat than water at room temperature.
A substance with more mass will have more heat energy, even if they are at the same temperature.
HEAT: The amount of heat energy something contains depends on three things!
Measures how fast an object is moving.
Speed = distance/time
If a car traveled 50 km in 25 minutes, its speed would be:
50 km/25 min = 2 km/min
Acceleration calculates how fast an object speeds up or slows down. It can be positive or negative.
Acceleration = (Vfinal-Vinitial)/time
A rolling ball slowed down from 5 km/hr to 2 km/hr.
It took 2 seconds to slow down.
Acceleration = 2 km/hr - 5 km/hr / 2s
-3 km/hr / 2s
- 1.5 km/hr/s
(which means the ball slowed down by 1.5 km/hr every second)
A force is a push or pull.
The force it takes to move something depends on its mass and how fast you want it to move.
Force = mass x acceleration
If the box this man is pushing has a mass of 10 kg and he pushes it to 2 m/s/s, he will use (10 x 2) 20 Newtons of force.
When a person or machine applies force to make something move, work is done.
Work = force x distance
If a ball is kicked with a force of 4 Newtons and it travels 10 m, then the work done on the ball was (4 x 10) 40 Joules.
Power measures how fast work is done.
Power = work/time
If a forklift moves a box, doing 300 Joules of work, in 10 seconds, then the power of the forklift is (300/10) 30 Watts.
The First Law states that an object in motion will stay in motion, and an object at rest will stay at rest unless a force acts on the object.
In other words……
The Law of Inertia
This golf ball will stay at rest on the tee until the unbalanced force of the swinging club causes it to move.
Examples of the 1st Law
Once the golf ball is in motion, it will continue moving in a straight line until the force of gravity pulls it to the ground.
Examples of the 1st Law
Force, mass, and acceleration are related. Greater force = greater acceleration. Greater mass = less acceleration.
This is expressed with the equation:
Force = mass x acceleration
F = m x a
The Law of Acceleration
The big rock and the little rock have the same acceleration (9.8 m/s/s). The big one is 10kg and the little one is 1 kg. Which one will hit the Earth with more force?
Examples of the 2nd Law
It will take more force to accelerate the big rock.
Examples of the 2nd Law
These two people throw a baseball as hard as they can. Which ball will have more acceleration?
Examples of 2nd Law
The Third Law states that for every action, there is an equal and opposite reaction.
The Law of Interaction
When you release the nozzle of a balloon, the air goes out the nozzle, and balloon flies in the opposite direction.
Examples of the 3rd Law
The canoe moves forward when you push backward with the paddles.
Examples of the 3rd Law
Chemical energy is the energy contained in chemical bonds between atoms. Energy is required when molecules are created or broken down.
Endothermic - a reaction that requires energy (in the form of heat).
Exothermic - a reaction that releases energy (in the form of heat).
A chemical change is expressed in a chemical equation.
The law of conservation of matter states that matter cannot be created or destroyed. This means that the amount of matter present BEFORE a chemical change must be the same as the amount of matter AFTER the change.
There is not the same number of atoms on each side of the equation.
The flow of electric charges carried through a material such as wire or other conductors
An electric charge that collects or builds up on the surface of an object
Kinds of Electricity
Materials that do not allow electric charges to flow freely through them
Any material that allows electric charges to move through it
Metals (esp. copper)
Conductors and Insulators
The speed of light is 300,000 km/s!
It is the fastest thing in the universe!
In an element square....
Atomic number - tells how many protons an atoms has. Also tells how many electrons, if the atom is neutral.
Atomic mass - the mass of the atom, equal to the number of protons and neutrons combined.
From this square, we can tell that Nitrogen has
Protons: 7 (from atomic number)
Electrons: 7 (from atomic number)
Neutrons: 7 (from atomic mass - atomic number)