MATTER
Chapter 20
Science matters
Word Bank
Chemistry, Matter, Volume, Solid, Liquid, Gas, Compressed,
Incompressible, Vapour, Diffuse, Particles, Microscopic , Molecules,
Evaporation, Temperature, Condensation, Freezing
Chemistry
Chemistry is the study of materials
Materials are the substances the world is made of e.g. air, water, rock, metal, wood plastic
Some materials are natural e.g. wool, wood
Some materials are man-made in laboratories e.g. plastic, glass.
Natural Materials
Wool, Wood, Copper, Marble etc….
Man–Made Materials
Plastic, Glass, Alloys etc....
Uses of Chemistry
Manufacture of : Plastics, Medicines, Fertilisers, Paints, Petrol, Synthetic Cloths
The name that scientists give materials is Matter
Matter is anything that occupies space (i.e. has volume) and has mass.
Matter exists as Solid, Liquid or Gas
These 3 forms are called the States of Matter
Properties of States of Matter
Solids
Solids have a definite shape.
Solids have a definite volume
Solids cannot be compressed easily
(incompressible)
Solids do not flow (spread over a
surface)
Properties
Liquids
Liquids have no definite shape
Liquids have a definite volume
Cannot be compressed easily
Liquids can flow and evaporate (liquids change to gas (vapour) at the surface).
Properties
Gases
Gases have no definite shape
Gases have no definite volume (they diffuse to fill the space they are given
They can be compressed easily, squeezed into smaller volume.
Summary of Properties
Solids
Liquids
Gases
Definite shape
Do not Flow
No definite shape
Flows
No definite shape
Diffuses
Definite volume
Definite volume
No definite volume
Hard to compress
Hard to compress
Easy to compress
Particle Theory
The Particle Theory is used to explain why solids liquids and gases have different properties
Particles are the microscopic molecules that make up matter
Particle Theory of Solids
Particles arranged in a regular pattern and cannot move out of position (definite shape and
means they cannot flow). The particles are tightly packed together (definite volume and
makes them incompressible). Strong forces hold the particles together
Particle Theory of Liquids
No regular arrangement of particles. Can slide around each other (this causes liquids to
have no definite shape and to flow). Particles are packed together (means liquids are hard
to compress and have a definite volume). Forces holding particles together are weaker than
in solids (allows more movement in liquids).
Particle Theory of Gases
Particles are much farther apart than in solids or liquids (can be compressed).
Particles can move quickly in all directions to fill available space (no definite shape or
volume and can diffuse). There are only weak forces between the particles.
Compression, Diffusion, Fluids
Compression: To push particles closer together so they have a smaller volume.
Diffusion: spreading out of particle in all directions to fill available space.
Since liquids and gases can flow they are called fluids
Changes of state
When solids melt to make liquids or liquids evaporate to make gases we call it a change of
state.
Melting Point : the temperature at which a solid changes to liquid, e.g. 00C for water.
When a solid is heated the heat energy allows the particles to shake faster and faster until
they have enough energy to slide around each other then the solid has melted
Evaporation is the changing of a liquid to a gas
When liquids are heated the particles at the surface get enough energy to break free from
the rest of the liquid and go into the air, this is evaporation
Wind speeds up evaporation by moving gas particles out of the way
Boiling Point: the temperature at which a liquid changes to a gas through the liquid
When a liquid is heated enough, the particles get enough energy to break free from each
other and make a gas, bubbles of gas start to form throughout the liquid rise to the top and
escape into the air
Condensation: Changing of a gas to a liquid.
When a gas is cooled the particles slow down and move closer and closer together until
they are all touching each other now the gas has become a liquid.
Freezing point: temperature at which a liquid changes to a solid
When a liquid is cooled the movement of the particle gets slower until they can no longer
slide around each other, the liquid is now a solid.
Changes of State