GCSE Physics₈₄₆₃

GCSE Physics Specification Specification for first teaching in 2016

21 Sep 2015

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4.3 Particle model of matter

The particle model is widely used to predict the behaviour of solids, liquids and gases and this has many applications in everyday life. It helps us to explain a wide range of observations and engineers use these principles when designing vessels to withstand high pressures and temperatures, such as submarines and spacecraft. It also explains why it is difficult to make a good cup of tea high up a mountain!

4.3.1 Changes of state and the particle model

4.3.1.1 Density of materials

Content	Key opportunities for skills development
The density of a material is defined by the equation: $d e n s i t y = \frac{m a s s}{v o l u m e}$ $[ρ = \frac{m}{V}]$ density, ρ , in kilograms per metre cubed, kg/m³ mass, m , in kilograms, kg volume, V , in metres cubed, m³ The particle model can be used to explain the different states of matter differences in density.	MS 1a, b, c, 3b, c Students should be able to recall and apply this equation to changes where mass is conserved.
Students should be able to recognise/draw simple diagrams to model the difference between solids, liquids and gases.	WS 1.2
Students should be able to explain the differences in density between the different states of matter in terms of the arrangement of atoms or molecules.	WS 1.2

Content

Key opportunities for skills development

The density of a material is defined by the equation:

$d e n s i t y = \frac{m a s s}{v o l u m e}$

$[ρ = \frac{m}{V}]$

density, ρ , in kilograms per metre cubed, kg/m³

mass, m , in kilograms, kg

volume, V , in metres cubed, m³

The particle model can be used to explain

the different states of matter
differences in density.

MS 1a, b, c, 3b, c

Students should be able to recall and apply this equation to changes where mass is conserved.

Students should be able to recognise/draw simple diagrams to model the difference between solids, liquids and gases.

WS 1.2

Students should be able to explain the differences in density between the different states of matter in terms of the arrangement of atoms or molecules.

WS 1.2

Required practical activity 5 : use appropriate apparatus to make and record the measurements needed to determine the densities of regular and irregular solid objects and liquids. Volume should be determined from the dimensions of regularly shaped objects, and by a displacement technique for irregularly shaped objects. Dimensions to be measured using appropriate apparatus such as a ruler, micrometer or Vernier callipers.

AT skills covered by this practical activity: AT 1.

This practical activity also provides opportunities to develop WS and MS. Details of all skills are given in Key opportunities for skills development .

4.3.1.2 Changes of state

Content	Key opportunities for skills development
Students should be able to describe how, w hen substances change state (melt, freeze, boil, evaporate, condense or sublimate), mass is conserved. Changes of state are physical changes which differ from chemical changes because the material recovers its original properties if the change is reversed.

Content

Key opportunities for skills development

Students should be able to describe how, w hen substances change state (melt, freeze, boil, evaporate, condense or sublimate), mass is conserved.

Changes of state are physical changes which differ from chemical changes because the material recovers its original properties if the change is reversed.

4.3.2 Internal energy and energy transfers

4.3.2.1 Internal energy

Content	Key opportunities for skills development
Energy is stored inside a system by the particles (atoms and molecules) that make up the system. This is called internal energy. Internal energy is the total kinetic energy and potential energy of all the particles (atoms and molecules) that make up a system. Heating changes the energy stored within the system by increasing the energy of the particles that make up the system. This either raises the temperature of the system or produces a change of state.

Content

Key opportunities for skills development

Energy is stored inside a system by the particles (atoms and molecules) that make up the system. This is called internal energy.

Internal energy is the total kinetic energy and potential energy of all the particles (atoms and molecules) that make up a system.

Heating changes the energy stored within the system by increasing the energy of the particles that make up the system. This either raises the temperature of the system or produces a change of state.

4.3.2.2 Temperature changes in a system and specific heat capacity

Content	Key opportunities for skills development
If the temperature of the system increases, the increase in temperature depends on the mass of the substance heated, the type of material and the energy input to the system.
The following equation applies: $c h a n g e i n t h e r m a l e n e r g y = m a s s \times s p e c i f i c h e a t c a p a c i t y \times t e m p e r a t u r e c h a n g e$ $[∆ E = m c ∆ θ]$ change in thermal energy, ∆ E , in joules, J mass, m , in kilograms, kg specific heat capacity, c , in joules per kilogram per degree Celsius, J/kg °C temperature change, ∆ θ , in degrees Celsius, °C. The specific heat capacity of a substance is the amount of energy required to raise the temperature of one kilogram of the substance by one degree Celsius.	MS 1a, 3b, c, d Students should be able to apply this equation, which is given on the Physics equation sheet, to calculate the energy change involved when the temperature of a material changes. This equation and specific heat capacity are also included in Energy changes in systems .

Content

Key opportunities for skills development

If the temperature of the system increases, the increase in temperature depends on the mass of the substance heated, the type of material and the energy input to the system.

The following equation applies:

$c h a n g e i n t h e r m a l e n e r g y = m a s s \times s p e c i f i c h e a t c a p a c i t y \times t e m p e r a t u r e c h a n g e$

$[∆ E = m c ∆ θ]$

change in thermal energy, ∆ E , in joules, J

mass, m , in kilograms, kg

specific heat capacity, c , in joules per kilogram per degree Celsius, J/kg °C

temperature change, ∆ θ , in degrees Celsius, °C.

The specific heat capacity of a substance is the amount of energy required to raise the temperature of one kilogram of the substance by one degree Celsius.

MS 1a, 3b, c, d

Students should be able to apply this equation, which is given on the Physics equation sheet, to calculate the energy change involved when the temperature of a material changes.

This equation and specific heat capacity are also included in Energy changes in systems .

4.3.2.3 Changes of state and specific latent heat

Content	Key opportunities for skills development
If a change of state happens: The energy needed for a substance to change state is called latent heat. When a change of state occurs, the energy supplied changes the energy stored (internal energy) but not the temperature. The specific latent heat of a substance is the amount of energy required to change the state of one kilogram of the substance with no change in temperature.
$e n e r g y f o r a c h a n g e o f s t a t e = m a s s \times s p e c i f i c l a t e n t h e a t$ $[E = m L]$ energy, E , in joules, J mass, m , in kilograms, kg specific latent heat, L , in joules per kilogram, J/kg Specific latent heat of fusion – change of state from solid to liquid Specific latent heat of vaporisation – change of state from liquid to vapour	MS 1a, 3b, c, d Students should be able to apply this equation, which is given on the Physics equation sheet , to calculate the energy change involved in a change of state. MS 4a AT 5 Perform an experiment to measure the latent heat of fusion of water.
Students should be able to interpret heating and cooling graphs that include changes of state. Students should be able to distinguish between specific heat capacity and specific latent heat.	WS 3.5

Content

Key opportunities for skills development

If a change of state happens:

The energy needed for a substance to change state is called latent heat. When a change of state occurs, the energy supplied changes the energy stored (internal energy) but not the temperature.

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

$e n e r g y f o r a c h a n g e o f s t a t e = m a s s \times s p e c i f i c l a t e n t h e a t$

$[E = m L]$

energy, E , in joules, J

mass, m , in kilograms, kg

specific latent heat, L , in joules per kilogram, J/kg

Specific latent heat of fusion – change of state from solid to liquid

Specific latent heat of vaporisation – change of state from liquid to vapour

MS 1a, 3b, c, d

Students should be able to apply this equation, which is given on the Physics equation sheet , to calculate the energy change involved in a change of state.

MS 4a

AT 5

Perform an experiment to measure the latent heat of fusion of water.

Students should be able to interpret heating and cooling graphs that include changes of state.

Students should be able to distinguish between specific heat capacity and specific latent heat.

WS 3.5

4.3.3 Particle model and pressure

4.3.3.1 Particle motion in gases

Content	Key opportunities for skills development
The molecules of a gas are in constant random motion. The temperature of the gas is related to the average kinetic energy of the molecules. Changing the temperature of a gas, held at constant volume, changes the pressure exerted by the gas.	WS 1.2
Students should be able to: explain how the motion of the molecules in a gas is related to both its temperature and its pressure explain qualitatively the relation between the temperature of a gas and its pressure at constant volume.	WS 1.2

Content

Key opportunities for skills development

The molecules of a gas are in constant random motion. The temperature of the gas is related to the average kinetic energy of the molecules.

Changing the temperature of a gas, held at constant volume, changes the pressure exerted by the gas.

WS 1.2

Students should be able to:

explain how the motion of the molecules in a gas is related to both its temperature and its pressure
explain qualitatively the relation between the temperature of a gas and its pressure at constant volume.

WS 1.2

4.3.3.2 Pressure in gases (physics only)

Content	Key opportunities for skills development
A gas can be compressed or expanded by pressure changes. The pressure produces a net force at right angles to the wall of the gas container (or any surface).	WS 1.2
Students should be able to use the particle model to explain how increasing the volume in which a gas is contained, at constant temperature, can lead to a decrease in pressure. For a fixed mass of gas held at a constant temperature: $p r e s s u r e \times v o l u m e = c o n s t a n t$ $[p V = c o n s t a n t]$ pressure, p , in pascals, Pa volume, V , in metres cubed, m³ Students should be able to calculate the change in the pressure of a gas or the volume of a gas (a fixed mass held at constant temperature) when either the pressure or volume is increased or decreased.	MS 3b, c Students should be able to apply this equation which is given on the Physics equation sheet.

Content

Key opportunities for skills development

A gas can be compressed or expanded by pressure changes. The pressure produces a net force at right angles to the wall of the gas container (or any surface).

WS 1.2

Students should be able to use the particle model to explain how increasing the volume in which a gas is contained, at constant temperature, can lead to a decrease in pressure.

For a fixed mass of gas held at a constant temperature:

$p r e s s u r e \times v o l u m e = c o n s t a n t$

$[p V = c o n s t a n t]$

pressure, p , in pascals, Pa

volume, V , in metres cubed, m³

Students should be able to calculate the change in the pressure of a gas or the volume of a gas (a fixed mass held at constant temperature) when either the pressure or volume is increased or decreased.

MS 3b, c

Students should be able to apply this equation which is given on the Physics equation sheet.

4.3.3.3 Increasing the pressure of a gas (physics only) (HT only)

Content	Key opportunities for skills development
Work is the transfer of energy by a force. Doing work on a gas increases the internal energy of the gas and can cause an increase in the temperature of the gas.
Students should be able to explain how, in a given situation eg a bicycle pump, doing work on an enclosed gas leads to an increase in the temperature of the gas.	WS 1.2

Content

Key opportunities for skills development

Work is the transfer of energy by a force.

Doing work on a gas increases the internal energy of the gas and can cause an increase in the temperature of the gas.

Students should be able to explain how, in a given situation eg a bicycle pump, doing work on an enclosed gas leads to an increase in the temperature of the gas.

WS 1.2

4.2 Electricity

4.4 Atomic structure