topic 3 - particle model of matter

state the equation linking density, mass and volume

density/ρ (kg/m³) = mass/m (kg) / volume/v (m³)

state what the particle model can be used to explain

• the different states of matter

• differences in density

explain how to draw simple diagram of a solid matter

• draw 9, equally-sized circles

• all the circles should be touching 2 other circles

• they should be arranged in a regular 3×3 pattern

explain how to draw simple diagram of a liquid matter

• draw 9, equally-sized circles

• all circles should be touching at least one other circle

explain how to draw simple diagram of a gas matter

• draw 4, equally-sized circles

• all circles should have no contact with other circles

explain what the density of solid matter is based on particle arrangement

• tightly packed arrangement leads to solids being high density matter

• due to the large amount of mass confined in a small volume

explain what the density of liquid matter is based on particle arrangement

• moderately close arrangement leads to liquids being moderate density matter

• due to the moderate amount of mass confined in a given volume

explain what the density of gas matter is based on particle arrangement

• widely spaced arrangement leads gases being low density matter

• due to small amount of mass spread out over a large volume

explain the method of determining the density of regular objects

1. measure the height, width and length of the object using a ruler

2. multiply these together to find the volume of the object

3. use an electric balance to measure the mass of the object

4. input these values into the equation d = m/v to find the density of the object

explain the method of determining the density of irregular objects

1. measure out a fixed volume of water into a measuring cylinder

2. use an electric balance to measure the mass of the object

3. gently submerge the object into the water fully and record the new volume of water

4. minus the initial volume of water from the final volume to find the volume of the water displaced

5. volume of water displaced is the volume of the object

6. use the volume and mass results in the equation d = m/v to find the density of the object

describe how, when substances change state, mass is conserved

• when the substance changes state, the particles in the matter rearrange and join back together to form a new substance

• but the number of atoms stays the same

• conserving the mass of the matter

state what kind of change changes of state are

physical changes

explain how physical changes differ from chemical changes

• physical changes - the material can recover their original properties if the change is reversed

• chemical changes - the material can’t recover their original properties if the change is reversed

explain why a material can’t recover their original properties if chemical changes are reversed

• when chemical changes occur, new products are formed

• these products have different chemical compositions to the reactants

state how internal energy is stored inside a system

by the particles that make up the system

state what internal energy is made up of

total kinetic energy + potential energy of all particles that make up the system

explain how heating affects energy stored within a system

• heating increases the kinetic energy of the particles within the system

• this either raises the temperature of the system

• or produces a change of state

• causing an increase in the system’s internal energy

state what happens if the temperature of a system increases

the kinetic energy of the particles in the system will increase

state what the temperature increase of a system is dependent on

• mass of the substance heated

• type of material

• energy input to the system

state the equation linking energy change, mass, specific heat capacity and temperature change

energy change (J) = mass (kg) x specific heat capacity (J/kg°C) x temperature change

state the symbol equation linking energy change, mass, specific heat capacity and temperature change

ΔE (J) = m (kg) x c (J/kg°C) x Δθ (°C)

explain what specific heat capacity of a substance is

• amount of energy required

• to raise the temperature

• of one kg of a substance

• by one degree celsius

state what the energy needed for a substance to change state is called

specific latent heat

state what happens to the internal energy and temperature of a system when the energy supplied changes

• internal energy changes

• temperature remains the same

explain what specific latent heat of a substance is

• amount of energy required

• to change the state

• of one kg of a substance

• with no change in temperature

state the equation linking energy for change of state, mass and specific latent heat

energy for change of state (ΔE)= mass (kg) x specific latent heat (J/kg)

state the symbol equation linking energy for change of state, mass and specific latent heat

ΔE = m x L

state what the specific latent heat of fusion is

change of state from solid to liquid

state what the specific latent heat of vaporisation is

change of state from liquid to vapour

explain how to interpret a heating graph

• horizontal line is when a substance is undergoing a change of state

• the temperature remains constant during the horizontal lines

• positive diagonal line is substance being heated

• the temperature increases during the positive diagonal lines

explain how to interpret a cooling graph

• horizontal line is when a substance is undergoing a change of state

• the temperature remains constant during the horizontal lines

• negative diagonal line is substance being cooled

• the temperature decreases during the negative diagonal lines

explain the differences between specific heat capacity and specific latent heat

• specific heat capacity - change in temperature

• specific latent heat - change in state

state the type of motion of gas molecules

random motion

state what the temperature of a gas is related to

the average kinetic energy of the gas molecules

state how changes in temperature of gases affects the pressure exerted by the gas

• increasing temperature increases the kinetic energy of the gas molecules in a constant volume

• which increases the frequency of successful collisions between gas molecules

• which generates force

• force is directly proportional to pressure

• thus causing an increase in pressure

explain how the motion of gas molecules is related to temperature

• temperature increase increases kinetic energy of molecules

• gases move in random motion

• due to higher kinetic energy than other states

• causing more collision between molecules

• and more force generated by more frequent collisions

• at constant volume

explain how the motion of gas molecules is related to pressure

• gases move in random motion

• due to higher kinetic energy than other states

• causing more collision between molecules

• and more force generated by more frequent collisions

• force is directly proportional to pressure

• so gas pressure is increased at constant volume

explain qualitatively the relation between temperature of gas and its pressure at constant volume

• as volume of container with a gas remains constant

• the pressure of a gas increases

• as its temperature increases

• due to increasing kinetic energy of molecules

• causing excess collisions between molecules and walls of container

• creating excess force

• force is directly proportional to pressure

state what allows a gas to be compressed or expanded

• compressed - decrease in pressure

• expanded - increase in pressure

explain what kind of force gas produces on the wall of the container holding the gas

• net force

• perpendicular to walls of container

explain how to use the particle model to explain how increasing volume of which gas is contained can lead to a decrease in pressure #

• pressure and area/volume are inversely proportional

• as pressure increases when there are more collision between gas molecules

• which generates excess force

• as volume increases, the space that the gas molecules have to move increases

• and space between gas molecules increases

• decreasing the chance of collisions between molecules and the walls of the container

state the equation that links pressure, volume and constant temperature

constant temperature (°C) = volume (m³) x pressure (Pa)

state the symbol equation that links pressure, volume and constant temperature

constant (°C) = V (m³) x p (Pa)

state the equation that links initial volume and pressure to final volume and pressure

pressure₁ (Pa) x volume₁ (m³) = pressure₂ (Pa) x volume₂ (m³)

state the symbol equation that links initial volume and pressure to final volume and pressure

p₁ (Pa) x V₁ (m³) = p₂ (Pa) x V₂ (m³)

state what work is in relation to force

work is the transfer of force

state what happens when work is done on a gas

• internal energy increases

• causing an increases in gas temperature

explain how doing work on an enclosed system leads to an increase in temperature of the gas - bicycle pump

• a bicycle pump pumps oxygen into a tire

• this will increase the number of gas molecules in the tire whilst the area remains the same

• this will increase the frequency of successful collisions between molecules and the walls of the tire

• the force of the collisions causes work to be done

• which increases the average kinetic energy of the molecules

• which increases the temperature of the oxygen through energy transfer to the thermal store of the oxygen