Particle model of matter

What are the 3 states of matter

• solid

• Liquid

• Gas

what’s the arrangement of particles in a solid

• strong forces of attraction between particles which holds them close together in a fixed position - forms a REGULAR LATTICE structure

• Because particles are fixed it keeps a definite shape and volume so cannot flow

• Can vibrate

What happens when you heat up a solid

Particles gain more kinetic energy and vibrate more which weakens the forces between them

When they reach the melting point they have enough energy to overcome and break their bonds

Solid melts into a liquid

What are the arrangements of a liquid

• Weak forces of attraction so the particles are free to move but still touching so a liquid is compact

• Therefore have a definite volume even though overall shape can change so can fit a container

What happens when you heat a liquid

• The particles gain more energy so particles move around faster which weakens the forces holding particles together.

• Once reached boiling point, the particles have enough energy to overcome and break the bonds all together

• Liquid evaporates into a gas

What’s the arrangement of gas particles

• very weak forces of attraction between particles so free to move

• No definite shape or volume

  → Always fill a container

• constantly moving with random motion

  → means particles can travel in any direction and end up being deflected by walls of containers

What happens when you heat a gas

• Particles get more kinetic energy

• which means the gas will either expand if in an expandable container or if in a fixed container the pressure increases

What happens when you cool a gas down

• particles won’t have enough kinetic energy to overcome the forces of attraction

• Bonds start to form between particles

• Condenses into a liquid

What happens when you cool a liquid

• particles won’t have enough kinetic energy to overcome the forces of attraction

• Even more bonds form, fixing particles in place

• Freezes into a solid

Within a closed system, what does and doesn’t change with states of matter

• mass WONT change as number of particles remain the same

• Density of the substance WILL change

  → solids have highest density and gases has lowest

What is density

A measure of mass a substance has per unit if it’s volume

What’s the equation for density

Density = mass / volume

Density = kg/m³

Mass = kg

Volume = m³

How do you calculate the density of a solid

1. Measure the mass by putting solid on balance

2. If a regular shape, to find the volume by measuring the length, width, and height with a meter or centre meter ruler

3. If the shape is irregular, place an eureka can filled with water and a measuring cylinder under the outlet (to collect the displaced water) and put the solid in. The volume of water measured in the cylinder is the volume

4. Use the density equation p=m/v to find out the density

How do you find the density of a liquid

1. Put a beaker on the balance and zero the balance

2. Pour liquid into the beaker and measure the mass

3. The amount of ml of liquid is the same as your volume e.g 10 ml is 10cm³

4. Use the density equation p= m/v to find the density

When measuring the density of liquid, how do you get a more accurate density

• Larger volumes as it minimises the effects of uncertainty

• Take multiple measurements to calculate a mean

When particles are heated up and gain energy meaning they gain energy in their kinetic energy store, what does this also increase

Their internal energy which also means the temperature increases

What is temperature

Measure of the average internal energy of all the particles in a substance

On a changing state graph when heating, why is it not a straight line

The energy that were providing is being used to weaken or break the forces holding the particles together

On a changing state graph for cooling the substance, why is it not a straight line

The state change involves formation of new bonds which counteracts the cooling

→ why the temperature stays constant during the change of state

What is latent heat

The exact amount of energy required to change the state of a substance why the temperature remains the same

So therefore is the energy required to change 1kg of a particular substance from one state to another without changing its temperature (heating )

Or the energy released to change 1kg of a particular substance from one state to another without changing temperature (cooling)

What does latent heat depend on

• type of substance

• Volume / amount of substance

What are the 2 types of specific latent heat

• specific latent heat if vaporisation = energy change when a substance changes between a liquid and gas

• Specific latent heat of fusion = energy ch age when a substance changes between a solid and a liquid (melts or freezes)

What’s the equation fir specific latent heat

Energy required/ released = mass x specific latent heat

E=mxl

What happens to a temperature of a substance whilst it changes state

Temperature remains constant

What’s pressure

Force exerted per unit to area

What is the equation for pressure

Pressure = force / area

How does a gas create pressure when in a container

Gas particles constantly move in random direction which causes them to collide with the walls, exerting a force

This creates pressure

What 2 factors increase the pressure of a gas

• more collisions with walls of the container

• Faster moving particles

What does the total pressure depend on

• How many collisions there are

• How much each collision involves

How does temperature effect pressure in a Fixed container

• if you heat up a gas, you transfer energy to the particles kinetic energy store, so the particles move faster

• This means there are more frequent collision with the walls of the container so each individual collison involves more force

• Therefore pressure increases with force

How does concentration effect pressure in a fixed container

• increased number of particles but same volume there is increases concentration.

• More particles to collide so more collisions and more frequent collisions

• Therefore a higher pressure as the concentration is increased

How does volume effect pressure in a fixed container

• if decreased volume so there is more particles per volume, there is a higher concentration

• Particles have a shorter distance to collide so more frequent collisions so higher pressure

• Therefore as volume decreases the pressure increases

What happens with changes with temperature and concentration in a flexible container

• an increase in force changes the volume as it causes the flexible container to expand

How are pressure and volume related

Inversely related

Pressure x volume = constant value

So when comparing 2 containers P1V1 = P2V2

What’s the unit of pressure

Pa

Pascells