Solids, Liquids and GasesWhat’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 ldi ng Bl ocks (Year 8)
The Three States of Matter
.
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
C onstantly move past
each other
Gas
No attraction between
par ticles
Far apart
Random arrangement
Vibrate
Move quickly in all
directions
Cli ck to move on
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
ways
Mechanical
Heat
Light
Chemical
Electrical
Sound
Nuclear
Law of conservation of energy
cannot be created or
destroyed but only changes from
Energy
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
Most activities in everyday life involve one form of energy
Work
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
3
The 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.
How ‘Heat’ Moves
Thermal energy in the form of
heat can move in three ways.
Conduction
Convection
Radiation
4
The Three Methods of Heat Transfer:
Conduction, Convection and
Radiation
25
Conduction
• Direct
contact of
particles
• Solids/liquids
/gases
• The handle
of a cooking
utensil
Radiation
• Transfer of
energy by
waves
• Only radiant
energy that
is absorbed
becomes
thermal
energy
• Lightbulb
• Fireplace
Convection
• Transfer of
energy by
bulk
movement of
matter
(fluids)
• Currents
(wind,water)
• Hot air
balloon
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
Items tha are More dense than the liquid
are at the bottom, Items less dense than
the liquid are floating at the top
The cube is less dense
than the liquid it is in
because you see the
cube floating
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
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
Formula for GPE (Gravitational
Potential energy) GPE = mgh
m=mass, g=gravity (9.8 m/s2), and h=height
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:
in the atom
protons
Charge
Location
(+)
in nucleus
Neutrons
no charge
Electrons
(-)
in nucleus
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 BONDINGElectrons 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 ldi ng Bl ocks (Year 8)
Atoms and Elements
Elements con sist of on ly on e type of particle. We call these particles
atoms.
They cannot be spli t into simpler, small er particles by chemical
methods.
The elements each have a name and a symbol.
Cli ck to move on
Bui ldi ng Bl ocks (Year 8)
Elements, Molecules and Compounds
Some el ements, such as the n oble
gases, exist as individua l atoms.
Often, elements con sist of two or more
a to ms join ed together. We call these
m olec ules.
If mo re than one type of atom is in a
m olec ule, we call it a compo und.
Cli ck to move on
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
Compressionallike a slinky Ex. Sound Waves
Looks
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.
As you can see when two waves line up in
phase...the resulting wave has more
amplitude (height) The waves are bigger
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
are not in phase and as you can see,
cancel each other out
• In Destructive Interference the waves get
SMALLER
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
The angle of incidence is EQUAL to the angle of
reflection
Refract: This means that waves travel
with different speeds in solids, liquids,
and gases. Refraction talks about how
the waves bend.
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.
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.
See how the sound waves are
able to move around objects.
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)
The man is applying a force that causes the 1,000 kg (kg
is a mass) car to accelerate .05 m/s2
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