Physics - Particle model of matter

Arrangement of solids

Particles are held next to each other in fixed positions by strong forces of attraction

Arrangement of liquids

Particles are in contact with each other. forces between the particles are weaker than in solids

Arrangement of gases

Particles are spread out. There are almost no forces of attraction between the particles.

Movement in solids

particles vibrate at fixed positions

Movement in liquids

particles are free to move randomly around each other

Movement in gases

particles move randomly at high speeds

Properties of solids

-high density

-fixed volume

-fixed shape (unless deformed by an external force)

-cannot be compressed

Properties of liquids

-lower density than solids

-fixed volume

-unfixed shape

-cannot be compressed

Properties of gases

-low density

-no fixed volume or shape

-can be compressed

-can flow

solid to liquid

melting

liquid to gas

evaporation

gas to liquid

condensation

liquid to solid

freezing

solid to gas

sublimation

gas to solid

deposition

kinetic theory of matter

For a given amount of a substance, its particles will have the most energy in the gas state and the least energy in the solid state

What happens when a change of state is taking place?

the temperature stays the same

internal energy

the sum of the kinetic and potential energies of all particles in the system

Why does the temperature stay the same whilst a substance is melting?

The energy is being used to break the intermolecular bonds

Specific latent heat of fusion

The energy needed to melt or freeze 1kg of a substance at a constant temperature (its melting point)

Specific latent heat formula

Energy = mass x specific latent heat

Specific latent heat of vaporisation

The energy needed to boil or condense 1kg of a substance at a constant temperature (its boiling point)

kinetic energy of particles

how fast the particles are moving (linked to temperature)

potential energy of particles

how the particles are arranged and the forces between them

How does changing state affect the internal energy?

it changes the potential energy of the particles as the particles move apart or get closer

internal energy formula

Internal energy = kinetic energy + potential energy

density

Mass per unit volume of a substance ( how many particles there are within a give space)

density formula

Density = mass/volume

How do you measure the density of a solid?

-use a balance to measure its mass

-for a regular solid use length, width and height to calculate the volume

-for irregular solids submerge it in a eureka can filled with water as the volume of water displaced is equal to the volume of the solid

-use the formula density=mass/volume to find the density

How do you measure the density of a liquid?

- Measure mass of empty beaker using a balance,

- Measure mass of beaker now containing liquid,

- Density = mass/volume

pressure

Force applied per unit area. (how much force is pushing on a surface)

pressure formula

pressure = force/area

Pressure in gases

Each particle collides with the container wall and exerts a tiny force on the wall.

Factors that affect gas pressure

- temperature

-volume

-number of particles

How does temperature affect gas pressure?

Raising the temperature of a gas makes the particles move faster, so they collide with the container walls more often. increasing the pressure

How does volume affect gas pressure?

If the volume of the container is made smaller, particles would hit the walls more often and the pressure will increase

How does the number of particles affect gas pressure?

If there are more gas particles, there would be more collisions, increasing the pressure

Boyle's Law

A principle that describes the relationship between the pressure and volume of a gas at constant temperature

Pressure in liquids

The force a liquid exerts on surfaces or objects in it. it happens because the weight of the liquid above pushes downwards

What factors affect pressure in liquids?

-depth

-density

-gravitational field strength

pressure in liquids formula

pressure = Height x Density x Gravity