AQA Physics 8463 - Particle Model of Matter Flashcards

73 vocabulary flashcards reviewing AQA Physics 8463 section 4.3 on the Particle Model of Matter.

Three States of Matter

Solid, liquid, and gas.

Particle Arrangement in a Solid

Particles are close together in a regular arrangement and vibrate about fixed positions.

Particle Arrangement in a Liquid

Particles are close together but can move past one another.

Particle Arrangement in a Gas

Particles are far apart and move rapidly in random directions.

Solid Shape Retention

Particles are held in fixed positions by strong forces between them.

Liquid Flowability

Particles remain close together but can move past one another.

Gas Compressibility

There are large spaces between its particles.

Density

Mass per unit volume.

Density Equation

$\text{density} = \frac{\text{mass}}{\text{volume}}$, or $\rho = \frac{m}{V}$

SI Unit of Density

Kilograms per cubic metre, $\text{kg/m}^3$

Common Density Unit

Grams per cubic centimetre, $\text{g/cm}^3$

Calculating Density

Divide mass by volume.

Mass Calculation from Density

$$\text{mass} = \text{density} \times \text{volume}$$

Volume Calculation from Density

$$\text{volume} = \frac{\text{mass}}{\text{density}}$$

Required Practical 5

Determines the density of regular and irregular solid objects and liquids.

Volume of a Regular Solid

Measure its dimensions and calculate its volume using the appropriate geometrical formula.

Volume of an Irregular Solid

Use water displacement in a measuring cylinder or displacement vessel.

Density of a Liquid

Measure a known volume of liquid and its mass, then calculate mass divided by volume.

Container Mass Accounting in Liquid Density

Only the mass of the liquid should be used in the density calculation.

Melting

A change of state where a solid changes to a liquid.

Freezing

A change of state where a liquid changes to a solid.

Boiling

A change of state where a liquid changes to a gas throughout the liquid.

Evaporation

Particles escape from the surface of a liquid to become a gas.

Condensation

A change of state where a gas changes to a liquid.

Sublimation

A change of state where a solid changes directly into a gas, or a gas directly into a solid.

Cause of Change of State

Energy is transferred to or from the substance.

Mass Conservation in State Change

Mass does not change when a substance changes state in a closed system; mass is conserved.

Nature of State Change

A physical change.

Reversibility of State Change

The substance remains the same material and can change back by reversing the energy transfer.

Temperature During State Change

The temperature remains constant while a pure substance changes state.

Constant Temperature Mechanism During State Change

Energy transferred changes the arrangement and potential energy of particles rather than increasing their kinetic energy.

Internal Energy

The total kinetic energy and potential energy of all the particles in a system.

Increasing Internal Energy

Heating the system or doing work on it.

Particle Kinetic Energy and Temperature

The average kinetic energy of the particles increases when temperature increases.

Effects of Heating a Substance

Its temperature may rise, or it may change state.

Specific Heat Capacity

The energy required to raise the temperature of $1\,\text{kg}$ of a substance by $1^\circ\text{C}$.

Thermal Energy Change Equation

$$\Delta E = m c \Delta \theta$$

Specific Latent Heat

The energy required to change the state of $1\,\text{kg}$ of a substance with no change in temperature.

Latent Heat Energy Equation

$$E = m L$$

Symbol $L$ in Latent Heat Equation

Specific latent heat in joules per kilogram, $\text{J/kg}$.

Specific Latent Heat of Fusion

The energy required to change $1\,\text{kg}$ of a substance from solid to liquid without changing temperature.

Specific Latent Heat of Vaporisation

The energy required to change $1\,\text{kg}$ of a substance from liquid to gas without changing temperature.

Vaporisation vs. Fusion Latent Heat

More energy is needed to separate particles much further apart when changing a liquid into a gas.

Particle Potential Energy During Melting

It increases as particles become less strongly bound in fixed positions.

Particle Potential Energy During Boiling

It increases greatly as particles separate to form a gas.

Heating Curve Flat Section

Shows energy being transferred while temperature remains constant during a change of state.

Heating Curve Sloping Section

Shows that temperature is changing, so average particle kinetic energy is changing.

Particle Model Applications

Useful for explaining properties of solids, liquids and gases, changes of state, density and gas pressure.

Limitation of Simple Particle Model

It represents particles as simple solid spheres and does not show their internal structure or all interactions accurately.

Cause of Gas Pressure

Gas particles colliding with the walls of their container.

Gas Particle Wall Collision

Its momentum changes and it exerts a force on the wall.

Gas Pressure and Wall Forces

Many particle collisions produce a total force; pressure is force per unit area.

Temperature Increase at Constant Volume (Gas Pressure)

Gas pressure increases.

Mechanism of Pressure Increase upon Heating

Particles move faster, collide with the walls more often and with greater momentum changes.

Average Kinetic Energy of Gas Particles

Increases as temperature increases.

Absolute Zero

The lowest possible temperature, $0\,\text{K}$.

Absolute Zero in Celsius

Approximately $-273^\circ\text{C}$.

Kelvin and Celsius Temperature Changes

A change of $1\,\text{K}$ is the same size as a change of $1^\circ\text{C}$.

Celsius to Kelvin Conversion

Add $273$ to the Celsius temperature.

Decreasing Gas Volume at Constant Temperature

Pressure increases for a fixed mass of gas.

Pressure-Volume Relationship

$\text{pressure} \times \text{volume} = \text{constant}$, or $p V = \text{constant}$.

Gas Law Equation for Two States

$$p_1 V_1 = p_2 V_2$$

Effect of Reducing Gas Volume on Pressure

Particles travel a shorter distance between wall collisions, so collisions occur more frequently.

Work Done on a Gas

Can increase the gas's internal energy and temperature.

Example of Doing Work on a Gas

Compressing it with a pump or piston.

Warming of a Bicycle Pump

Work done compressing the gas increases its internal energy, raising its temperature.

Density Calculation Unit Verification

Make sure mass and volume units are compatible with the required density unit.

Cubic Centimetres in One Cubic Metre

$$1{,}000{,}000\,\text{cm}^3$$

Conversion of $1\,\text{g/cm}^3$ to $\text{kg/m}^3$

$$1000\,\text{kg/m}^3$$

Temperature Difference Equivalency

The size of one kelvin equals the size of one degree Celsius, so temperature differences have the same numerical value.

Specific Heat Capacity vs. Specific Latent Heat

Specific heat capacity changes temperature without changing state; specific latent heat changes state without changing temperature.

First Step in Latent Heat Calculations

Identify whether the change is fusion or vaporisation, then choose the correct specific latent heat.

Conservation of Energy During Heating

Energy is conserved; it is transferred into the system and changes particle kinetic and/or potential energy.