Solids, Liquids and Gases-

What’s the difference?

Solids- you see the particles are packed

very closely together and not really moving

around a lot. They vibrate in place.

Liquids- you see the particles have a little

more energy and are now able to move

around. For this reason, it is said that

liquids can “flow”

Gases- The particles have a whole lot of

energy and move freely at high speeds

Bui lding Blocks (Year 8)

.

Solid

� Particles held tightly� Very close together� Regular arrangement� Vibrate� Can’t move from place to place

Liquid

� Particles held weakly� Very close together� Random arrangement� Vibrate� Constantly move past each other

Gas

� No attraction between particles� Far apart� Random arrangement� Vibrate�Move quickly in all directions

The Three States of Matter

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Energy

The ability to do Work

Nature of Energy

*Universe is made up of matter and energy

*The Sun is the major Source of Energy for Earth. Others include Nuclear and

Geothermal

• Energy does not occupy space or have mass

• Energy comes in many forms

Forms of Energy

Energy appears in many forms. It can be transformed in many waysMechanicalHeatLightChemicalElectrical

SoundNuclear

Law of conservation of energy

Energy cannot be created or destroyed but only changes from one form to another.

Example: Chemical to heat

In a burning candle: the chemical energy in the candle is not lost but changed to heat energy (and light energy)

Energy Transformations

Work

Most activities in everyday life involve one form of energy

bring transferred into another.

Example:

Chemical energy in gasoline is transformed into mechanical

energy in an automobile engine

Energy, in the form of heat, is almost always one of the

products of energy transformations

CAN YOU THINK OF ANY ENERGY

TRANSFORMATIONS?

Energy transfer

Energy always

travels from hot to

cold or

warmer to

cooler.

Ex. If you put an ice cube in you hand, it

melts.

Your hand transfers warmer energy to the

colder ice cube to make it melt

3The Nature of Heat

Heat moves in only one direction:

• Under normal conditions and in nature, heat energy will ALWAYS flow the warmer object to the cooler object.

• Heat energy will flow from one substance to another until the two substances have the same temperature.

4How ‘Heat’ Moves

Thermal energy in the form of heat can move in three ways.

Conduction

Convection

Radiation

The Three Methods of Heat Transfer:

Conduction, Convection and

Radiation

25Conduction

• Direct contact of particles

• Solids/liquids/gases

• The handle of a cooking utensil

• Transfer of energy by waves

• Only radiant energy that is absorbed becomes thermal energy

• Lightbulb

• Fireplace

• Transfer of energy by bulk movement of matter (fluids)

• Currents (wind,water)

• Hot air balloon

Radiation Convection

What Insulation does… In this example, we see a home that is exposed.

There are pieces of

insulation lining the

walls, ceilings and

floors. This helps to

keep the warmer air

from moving out to the

cooler air

Density Density refers to

basically how heavy something is…

Simply put, if something is more dense, it

will sink. If something is less dense, it

will float.

Both the liquid and the object that

is placed in the liquid will have a

density

Density = mass/Volume

The cube is less dense

than the liquid it is in

because you see the

cube floating

Items tha are More dense than the liquid

are at the bottom, Items less dense than

the liquid are floating at the top

Kinetic vs. Potential

Energy

Kinetic energy (KE) is

energy because something

is MOVING

Formula for KE = ½

mv2 m= mass and v=

velocity

Potential energy (PE)

is stored energy

Formula for GPE (Gravitational

Potential energy) GPE = mgh

m=mass, g=gravity (9.8 m/s2), and h=height

See the difference between the energies.

Potential is at its highest during the time

the bike rider is high up on the hill. KE

increases as the rider begins moving up or

down the hill

Periodic Table

What are Atoms?

This is the periodic table you

will see on the test

Every element on this periodic table is

made up of atoms. Atoms are the smallest part of each

of these elements.

Atoms have 3 particles: Charge Location

in the atom

protons (+) in nucleus

Neutrons no charge in nucleus

Electrons (-) in energy level

around the nucleus

Look at the atomic number to see how many protons

and also how many electrons you have in the atom

You can figure out your neutron # by looking at the atomic mass. Neutron #

= atomic mass – atomic number

proton number NEVER changes electrons and neutrons do

Periodic Table

How electrons can change Groups or Families- run up and down,

there are 8 of them. Number each

column from left to right starting with 1

-This helps you remember that’s how many electrons are in the outer

energy level OR VALENCE ELECTRONS. (Ex. Group VA should

have a 5 on top of it if you numbered it correctly. The 5 tells you

that every element in this group has 5 electrons in the outer energy

level)

- Atoms want 8 electrons in their outer energy level. 8 IS

GREAT!!! Nitrogen has 5 electrons and wants 3 more to be

GREAT OR STABLE!

Elements will bond with other elements to be STABLE AND

GREAT!!

An Atom of an element is considered NEUTRAL before it bonds with other

elements. NEUTRAL means the protons (+ ) and electrons (-) are EQUAL

Two major types of bonding can happen:

COVALENT BONDING- Electrons are shared

IONIC BONDING- Electrons are given and taken (Elements are

charged (more (+) protons or more (-) electrons and are now called IONS)

Please note that Group VIIIA (or you should have an 8 on top) has all 8

Electrons. Group 8 is GREAT because they don’t need anymore electrons.

They are called NOBLE GASES. Group 7 is called the HALOGENS.

Periodic

Table

How neutrons can

change

Protons and neutrons make up the atomic

mass

You can have more or less neutrons in

the nucleus that makes it heavier or

lighter. We call these isotopes

Ex. C-14, C-15. C-12 These are all isotopes ( just different

masses) of Carbon.

C-14 still has 6 protons

(NEVER CHANGES) and 6

electrons in a neutral atom. But

the 14 is the new atomic mass.

So the # of neutrons in a C-14

atom is 8 neutrons

Bui lding Blocks (Year 8)

Elements, Molecules and Compounds

Some elements, such as the noble gases, exist as individua l atoms.

Often, elements consist of two or more atoms joined together. We call these molecules.

If more than one type of atom is in a molecule, we call it a compound.

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Bui lding Blocks (Year 8)

Atoms and Elements

Elements consist of only one type of particle. We call these particles atoms.

They cannot be split into simpler, smaller particles by chemical methods.

The elements each have a name and a symbol.

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Waves Waves are repeating disturbances that transfer

energy through a medium (mediums are solids,

liquids, and gases)

Remember: Waves ONLY TRANSFER ENERGY.

The medium they’re in does NOT move. Ex. In

water waves, it looks like the water is moving from

one place to another, but it’s just the energy that’s

moving through the water

There are 2 major kinds of waves that NEED a

medium

Transverse – Ex. Water Waves

Compressional- Looks

like a slinky Ex. Sound Waves

Electromagnetic Waves- these are waves that

DON’T NEED a medium to transfer energy. The

Sun’s energy gets to the Earth because of

Electromagnetic waves.

Sound Waves

What is sound?

Sound is a compressional wave which travels through the air through a series of compressions and

rarefactions.

Sound travels through different media.

We hear sound which usually travels through air. Sound also travels through water and various solids.

Sound travels different speeds in different media. Sound typically travels faster in a solid that a liquid and faster in

a liquid than a gas.

The denser the medium, the

faster sound will travel.

The higher the temperature, the

faster the particles of the

medium will move and the faster

the particles will carry the sound.

Constructive Vs. Destructive

interference

Constructive Interference is when

you see two or more waves

overlapping and the crests are lined

up with crests and the troughs are

line up with troughs.

In Constructive Interference the waves get

BIGGER

Destructive Interference is when you

see two or more waves overlapping

BUT the crests are lined up with

troughs and the troughs are line up

with crests.

• In Destructive Interference the waves get

SMALLER

As you can see when two waves line up in

phase...the resulting wave has more

amplitude (height) The waves are bigger

In destructive interference, the waves

are not in phase and as you can see,

cancel each other out

How waves behave… Waves

can: Reflect: This means that the wave

hits a reflective surface, the wave

bounces off with an angle that is

the same as the wave going into

the surface. THE ANGLES ARE

EQUAL

Refract: This means that waves travel

with different speeds in solids, liquids,

and gases. Refraction talks about how

the waves bend.

Diffract: This means that the waves will

move around an object that is in the way.

Sound waves are able to diffract very well.

They are able to move or DIFFRACT around

buildings and mountains.

Here we see how the pole looks bent as

it enters the water. This is refraction.

The light waves slow down when they

enter the water and appear to bend.

See how the sound waves are

able to move around objects.

The angle of incidence is EQUAL to the angle of

reflection

Newton’s 3 Laws

We will try to summarize Newton’s 3 laws in

“English”

First law- Tells us if an object is moving, it will keep

moving unless a net or unbalanced force makes it stop.

(Ex. Car will keep going until it hits something to make it

stop) Or if the object is stopped, it won’t move unless a

net or unbalanced force makes it move.

Second law- Let’s call this the

F=ma Law. Remember the

formula. It says that an object

will accelerate if an object has a

certain force being applied (put

on it)

Third law- This is the action/reaction law.

This law states that if you have a force

acting in one direction….there is an equal

and opposite force acting in the opposite

direction

An example of Newton's 3rd Law

The man is applying a force that causes the 1,000 kg (kg

is a mass) car to accelerate .05 m/s2