Particle model of matter

What is the arrangment of particles in a solid?

• Very close together

• Regular patter

• Vibrate but do not move

What is the arrangment of particles in a liquid?

• Close together

• Not in a regular pattern

• Can move around eachother

What is the arrangment of particles in a gas?

• Very far apart

• Not in a pattern

• Move very rapidly

What is density?

The density of a material tells us the mass for a given volume

(How much mass is packed into its volume)

What is mass?

Mass is the amount of matter or substance that makes up an object

How is density calculated?

P = M / V

Density(Kg/m³) = mass(Kg) / volume(m³)

What are the densitys of solids,liquids and gases

• Solids have a high density as their particles are closely packed together (a lot of mass)

• Liquids have a high density as their particles are close together (a lot of mass)

• Gases had a low density as their particles are very far apart (a low mass)

Why is polystrene a solid with a low density?

Has open structure and is fulled with air spaces

What are regular objects?

Objects that have dimensions easy to measure

What are irregluar objects?

Objects with dimensions that can not easily be measured

Required pratical 5: density of regular objects

• First, find the mass of your regular object using a balance

• Then work out the volume of the cube, using a ruler to measure the length of the side

• The volume equals the length of the side cubed so times you measurement by three

• Divide the mass and volume to find the density

Required pratical 5: density of irregular objects

• Find the mass of the irregular object using a balance

• Fill a eureka can with water which has a spout which allows the water to flow out the can

• Place the object into the water

• This will cause the water to be displaced and flow out of the spout

• Measure the volume of water that was displaced using a measuring cylinder

• This volume is the same as the volume of the object

• Calculate the density by dividing these two number

What is internal energy?

Internal energy is the energy stored in a system by the particles

The internal energy is the total kinetic energy and potential energy of all the particles that make up a system

How does the internal energy change in the changes of states in solids, liquids and gas

As particles in solids → liquids → gas movements increase in this order, there is a increase in kinetic and potential energy

This means if you heat a solid, we increase the internal energy as it turns to a liquid

If you change the states from gas → liquid → solid movement decrease as there is a decrease of kinetic energy and potential energy

If you cool a gas down, then we reduce the internal energy as the gas will change to a liquid Wha

What is sublimation?

A solid turning directly to a gas

What happens to mass when the states of matter change?

Mass is conserved as we are not adding or taking particles away

Are the changes of state physical changes or chemical changes?

Physical changes as if we reverse the change, the materials recover back to their original properties

Evaporation is when a liquid turns to a gas but…

only on the surface of a liquid

In this case, only the particles on the surface have enough energy to turn into gas

What is specific heat capacity?

The specific heat capacity of a substance is the amount of energy required to raise 1 kg of the substance by 1’c

What is the equation for specific heat capacity?

△E = m x c x △θ

Change in thermal energy(J) = mass(Kg) x specific heat capacity(J/kg ‘c) x temperature change (‘c)

What will happen in heating graphs?

When the substance heats, we increase the temperature as we increase the energy particles

When the substance starts to change state eg melts, the temperature stops increasing and stays constant

What will happen in cooling graphs?

What happens to the force of attraction as we add energy?

It is weakening/breaking

What is the latent heat?

The energy needed for a substance to change state

Does the temperature change during the change of state?

No, the internal energy store is increased

What is the specific latent heat of a substance?

The specific latent heat is the amount of energy required to change the state of one kilogram of the substance with no change in temperature

What is the specific latent heat energy of fusion?

The energy required to change on kg of a substance from a solid to a liquid with no change in temperature

What is the specific latent heat of vaporisation?

The energy required to change 1 kg of a substance from a liquid to a vapour with no change in temperature

What calculation is used to find the energy for a change of state?

E = m x L

Energy for a change of state(J) = mass(Kg) x specific latent heat(J/kg)

What Whgas pressure due to?

The pressure of gas it due to the particles colliding with the walls of the container the gas is held in

What are the gas particles exerting when colliding with the walls of the container?

Pressure

How can we increase the pressure?

• Increase the number of collisions

• Increase the energy of each collision

How can we increase the energy of the particles in gas?

Increase the temperature

What is the temperature of a gas related to?

The average kinetic energy