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1. Unit 7 MATTER AND FORCES SUMMARY
Everything in the Universe is made up of matter
MATTER
It is the amount
of matter in an
object. We
measure it in
grams (g). 1000
grams = 1
kilogram
Properties
Color, odor
and taste
Matter is made
up of atoms.
Molecules are groups
of atoms
Hardness DensityMass Volume Solubility
It describes how
much space
matter occupies.
It is measured in
mililiters (ml).
1000 ml = 1 litre
It is the amount of matter
in a volume. We measure
density in kilograms per
litre (kg/l). Density =
mass/volume. It explains
why some objects float in
water while others sink.
When a solid object is in a liquid…
… it will float if its
density is lower
than the density of
the liquid.
… it will sink if
its density is
higher than the
density of the
liquid.
It is the scratch-resistance
of a solid. Diamonds are the
hardest natural solids.
It is the ability of a
substance to dissolve in
other substance and form a
solution. Ex. Sugar
dissolves well in water,
whereas oil does not.
Thermal conductivity
It is the ability of certain substances to
conduct or transfer heat. Metals, such as
iron or copper, are good heat conductors,
while materials such as wool, wood,
paper, plastic or glass are good heat
insulators.

2. Unit 7 MATTER AND FORCES SUMMARY
TYPES OF
MATTER
Pure substances
Heterogeneous mixtures: you can see the different
components (salad, rocks…)
They consist of just one type of matter.
For example: gold, iron, salt, sugar, minerals.
Substances in a mixture can be
separated using different
methods
Filtration is the operation used for the
separation of solids from fluids by interposing
a medium through which only the fluid can
pass. Oversize solids in the fluid are retained
Sieving We can use a sieve to separate solids
of different sizes, such as pebbles from sand.
Evaporation is a
type of vaporization
of a liquid that
occurs only in the
surface of a liquid.
Mixtures They consist of two or more types of matter.
Homogeneous mixtures: you cannot see the different
components (seawater, air…)
Alloys are another type of homogeneous mixtures in
which one or more substances are always a metal.
Bronze: copper + tin Steel: iron + carbon

3. Unit 6 MATTER SUMMARY
FORCES A force is a push or pull that acts on an object. We can’t see forces, but we
can see and feel their effects. Forces can make things move, stop, speed up,
slow down, or change direction. Forces can also make things change shape.
CONTACT FORCES
They act through physical contact.
- Friction: is the force that exists
when two objects rub against each
other. Friction acts in the opposite
direction to the direction of
movement. It can slow down or
stop a moving object. Air friction
slows down a parachute and
water friction slows down a
kayak or a boat.
- Buoyancy- is the ability of objects
to float. It is an upward force
which acts in the opposite direction
to gravity on objects immersed in
a liquid. If you put an ice cube in a
glass of water, gravity pulls the ice
cube down and the buoyant force
pushes it up.
NON-CONTACT FORCES
They act from a distance.
- Magnetism – is a force of
attraction or repulsion caused
by magnetic materials.
Magnets attract metals and
also make compasses work.
- Gravity – is a force which
attracts all objects towards the
ground. Larger bodies, such as
planets, have a stronger
gravitational force. Gravity
stops everything on Earth from
flying off into outer space and
also causes objects to fall to the
ground. Astronauts float in
space because there is no
gravity there.
Types
A NEW WORLD OF MATERIALS
Scientists and engineers
create of modify materials to
make them perform better.
IMPROVING OUR HEALTH
A special ceramic material is
used to place hip and knee joints
for artificial joints. It is also used
by the dentists for fillings, to
repair teeth.
ALLOYS
They are mixtures of two or more
elements and one of them must be a
metal. Ex steel.
RECENT BREAKTHROUGH
Ex. Concrete Cloth (a durable a
flexible waterproof building
material of cement
sandwiched between fabric
that can be used to make
emergency shelters)
NEW MATERIALS IN EVERYDAY LIFE
Ex. Non-stick ceramic coating,
polar fleece fabric.