Forces of attraction are less effective than solid
Fixed volume, takes shape of container.
Have more kinetic energy than solid
Solid
Strong forces of attraction
Cannot be compressed
Regularly arranged
Fixed volume and shape
Particles are closely compact
Particles don't move they vibrate around a fixed point
Have least kinetic energy
Gas
Have most kinetic energy
No fixed shape or volume
No arrangement
Move randomly
Almost no forces of attraction
Interconversions
Solid and Liquid
Solid to Liquid = Melting
Heat a solid, energy provided makes particles vibrate faster eventually vibrate
so fast that the forces of attraction become weak and are no longer strong
enough to hold particles together. Solid melts. As liquid particles have more
kinetic energy so solid particles has to be supplied with kinetic energy to
convert to a liquid. Melting Point - temperature at which solid melts.
Liquid to Solid = Freezing
Liquid cooled, particles move slowly, force of attraction will hold
the particles together. Freezing Point: Temperature at which
liquid freezes
Liquid and Gas
Liquid to Gas = boiling / evaporation
Boiling
Occurs when a liquid is heated so strongly so that particles
are moving fast enough to overcome all the forces of
attraction between them.
the stronger the forces of attraction, the higher the boiling point
because more energy is needed to overcome these forces of
attraction.
If gas is cooled, the particles eventually move
slowly enough that the forces of attraction
between them start to form and hold them
together as a liquid. The gas condenses
Evaporation
In any liquid or gas, the average speed of the particles
varies with temperature. But at each temperature,
some particles will be moving faster than the average.
Some very fast particles at the surface of the liquid have
enough kinetic energy to overcome forces of attraction -
they will break away to form a gas.
If a liquid is in a closed container, particles in the gas will be
colliding with the particles at the surface of liquid. If they are
moving slowly enough then they will be held by forces of
attraction and become part of liquid.
In a closed container evaporation and condensation will occur at same time.
Gas to Liquid = Condensation
Difference between Boiling and Evaporation
Evaporation occurs at any temperature, but boiling occurs at one
temperature - the boiling point of liquid.
Gas and Solid
Gas to Solid = Deposition
Solid to gas = Sublimation
Very few substances can change
directly from a solid to gas or gas to
solid, at normal pressure.
Example : Carbon dioxide. At ordinary pressure there is no such thing as liquid
carbon dioxide - it directly turns from solid to a gas.
Working out physical state of a substance at a
particular temperature
A substance below its melting point = SOLID
Between melting point and boiling point = LIQUID
Above its boiling point = GAS
Diffusion
Definition: The random movement of gas or liquid particles from
an area of high concentration to an area of low concentration
Gas particles diffuse quicker than liquid particles because
the particles move faster and are already more spread out
Particles in liquid are much closer so there is less space for particles
to move without colliding with one another
Solid particles do not diffuse because they do not move
out of position
Lighter particles diffuse faster than heavier particles