Definite shape and volume (holds shape
and volume).
Liquids
Definite volume and indefinite shape. They
take the shape of the container.
Gases
Indefinite volume: they can be compressed.
Indefinite shape. They take the shape of the
container
CHANGES OF MATTER
Physical
Reversible and irreversible
Chemical
Most chemical changes are irreversible.
Combustion,oxidation and fermetation.
Matter suffers changes of state
MATTER AND ITS PROPERTIES
Matter is made out of atoms.
colour, odour and taste.
VOLUME: how much space matter occupies. We measure
volume in mililitres (ml). 1l= 1000 ml
DENSITY: The amount of matter in a volume. We measure it
in kilograms per litre (kg/l)
HARDNESS is the scratch-resistance of a solid. Diamonds
are the hardness natural solid. Talc is the softess material.
THERMAL CONDUCTIVITY is the ability of the susbtances to
conduct or transfer heat.
SOLUBILITY: is the ability of a substance to disolve in
another substance and form a solution. Sugar disolves well
in water whereas oil does not.
MASS is the amount of matter in an object. An apple has a
greater mass than a grape. We measure mass in grams (g).
1kg=1000g.
WHAT TYPES OF MATTER ARE THERE?
PURE SUBSTANCES
Consists of only one type of matter
such as table salt, silver, gold, copper or
pure water.
MIXTURES
are made up of two or more pure
substances.
HOMOGENEOUS MIXTURES: such as
the air we breathe or sea water. We
cannot see the individual substance.
HETEROGENEOUS MIXTURES: such as
sand or a salad. We can see the
individual substances.
We can separate the substances in
mixtures through FILTRATION,
EVAPORATION AND SIEVING
FORCES AND ITS
EFFECTS
Forces can make things MOVE, STOP, SPEED
UP, SLOW DOWN or CHANGE DIRECTION.
NON-CONTACT FORCES
MAGNETISM: force of attraction or repulsion
caused by magnetic material, such as
magnets.
GRAVITY is a force which attracts all objects
towards each other, such as planets which
have a stronger gravitational force. In space
there is no gravity and astronauts float there.
Force is a push and pull that acts on
an object. We can see their effects.
CONTACT FORCES
FRICTION is a force that exists when two objects rub
against each other. It acts in the opposite direction of
movement. It can slow down or stop a moving object.
BUOYANCY is teh ability of objects to float. It is an upward
force which acts in the opposite direction to gravity on
objects immersed in a liquid.
WHY SOME OBJECTS FLOAT IN
WATER AND OTHERS SINK?
DENSITY (kg/l) explains why some objects float in
water while others sink.
If an object has lower density than water, it floats. If an
object has higher density than water , it sinks.
The density of water is 1 Kg/l. The density of steel is
around 8 kg/l.
The ability to float depends on the AVERAGE
DENSITY that take into account all materials that
the object is made of.
A NEW WORLD OF
MATERIALS
Nearly everything we use is made of materials
created or modified by scientists and engineers
(man-made materials).
ALLOYS: It is created by mixing two or more
elements, one of wich must be a metal (cooper,
silver,...). BRASS is an alloy of copper and zinc.
STEEL is the most commonly used alloys in
everyday life. STAINLEES STEEL is alloy which
resists rust and corrosion.
ARTIFICIAL JOINTS is made of a special CERAMIC
MATERIAL which is hard and has no effects on
our body.
CERAMIC material are also used by dentists to
repair teeth.
New materials in every day life are NON-STICK
CERAMIC COATING for cookware; POLAR FLEECE
FABRIC to made pieces of clothing from recycled
plastic bottles and CONCRETE CLOTH.
NYLON ia a chaper man-made material sobstitute for silk (fabric, cookware,
electronics industry). PLASTIC is used in almost all areas of everyday living
due to their versatility (construction, packaging, toys..). POLYESTIRENE is a
versatile plastic used to make a wide variety of consumer products
(Refrigerators, food trays, food packaging,...)