The three states of matter .1

what is the kinetic particle theory

The kinetic particle theory of matter is a model that describes the arrangement, movement and energy of particles in a substance

closeness of particles - solid

very close

closeness of particles - liquid

close

closeness of particles - gas

far apart

arrangement of particles - solid

regular pattern

arrangement of particles - liquid

randomly arranged

arrangement of particles - gas

randomly arranged

movement of particles - solid

vibrate around a fixed position

movement of particles - liquid

move around each other

movement of particles - gas

move quickly in all directions

energy of particles - solid

low energy

energy of particles - liquid

greater energy

energy of particles - gas

highest energy

solids shape, flow + compression

• have a fixed shape and cannot flow, because their particles cannot move from place to place

• cannot be compressed (squashed), because their particles are close together and have no space to move into

liquid shape, flow + compression

• flow and take the shape of their container, because their particles can move around each other

• cannot be compressed, because their particles are close together and have no space to move into

gas shape, flow + compression

• flow and completely fill their container, because their particles can move quickly in all directions

• can be compressed, because their particles are far apart and have space to move into

solid → liquid

melting

liquid → gas

evapourating or boiling

gas → liquid

condensing

liquid → solid

freezing

solid → gas

sublimation

what must happen in order for a substance for these changes of state to happen.

Energy must be transferred, by heating

what happens during these changes of state

During these changes the particles gain energy

what is the energy that particles gains used for

• break some of the bonds between particles during melting

• overcome the remaining forces of attraction between particles during evaporating or boiling

what happens during evaporation

In evaporation, particles leave a liquid from its surface only.

what happens during boiling

• In boiling, bubbles of gas form throughout the liquid.

• They rise to the surface and escape to the surroundings, forming a gas.

what does the amount of energy needed to change state from solid to liquid, and from liquid to gas, depends on

• the strength of the forces between the particles of a substance.

• The stronger the forces of attraction, the more energy is required.

what does stronger the forces between particles mean

the higher its melting and boiling points.

when can evaporation also take place

Evaporation can take place below the boiling point of a substance.

what is the melting point of a substance

the temperature at which it melts or freezes

what is the boiling point of a substance

The temperature at which a substance rapidly changes from a liquid to a gas

what happens to the surroundings during condensing + freezing

• Energy is transferred from a substance to the surroundings when a substance condenses or freezes.

• This is because the forces of attraction between the particles get stronger.

how can you determine the state of a substance at a given temperature from its melting point and boiling point

Temperature	Predicted state
Given temperature < melting point	Solid
Given temperature is between melting and boiling points	Liquid
Given temperature > boiling point	Gas

what are limitations of the particle model

The particle model assumes that particles are solid spheres with no forces between them. However:

• particles are not solid, since atoms are mostly empty space

• many particles are not spherical