particle model of matter

• How is density defined?

  Density is defined as mass per unit volume.
• What is the formula for density?

  The formula for density is $\rho =$$\frac{m}{V}$.
• What units are used for density?

  Density is measured in kilograms per metre cubed (kg/m³).
• How does density depend on atomic spacing?

  Density depends on the spacing of the atoms in matter.
• Why do solids and liquids have similar densities?

  Solids and liquids have similar densities because the space between particles does not change significantly.
• What is the usual density comparison between liquids and solids?

  Usually, liquids have a lower density than solids.
• What is the main exception to the density comparison between liquids and solids?

  The main exception is ice and water, where ice is less dense than water.
• How does the density of gases compare to that of solids and liquids?

  Gases have a far lower density than solids and liquids.
• What happens to the spacing between atoms in gases?

  The spacing between atoms in gases increases by a factor of ten.
• What is the relationship between energy and density in gases?

  Particles in gases have lots of energy to move, leading to a significant increase in volume and a decrease in density.
• What happens to mass during a change of state?

  Mass is conserved during a change of state.
• If 20g of liquid evaporates, what will be the weight of the gas produced?

  The gas produced will also weigh 20g.
• Why are changes of state considered physical changes?

  Changes of state are considered physical changes because the material retains its original properties when reversed.
• What are the different changes of state?

  • Melting
  • Freezing
  • Evaporating
  • Condensing
  • Sublimation
• What is internal energy?

  Internal energy is the energy stored by particles within a system.
• What forms can internal energy take?

  Internal energy takes the forms of kinetic energy and potential energy.
• What happens to the energy of particles when a system is heated?

  Heating increases the energy that particles have, raising the internal energy.
• What can heating a system do to its temperature?

  Heating a system can either raise its temperature or produce a change of state.
• What is specific heat capacity?

  Specific heat capacity is the amount of energy required to raise the temperature of 1kg of a substance by 1°C.
• What is the formula for change in thermal energy?

  The formula for change in thermal energy is $\Delta E =$$m \times c \times \Delta T$.
• What does $\Delta E$ represent in the thermal energy formula?


  $\Delta E$ represents the change in thermal energy, in joules (J).
• What does $c$ represent in the thermal energy formula?


  $c$ represents the specific heat capacity, in joules per kilogram per degree Celsius (J/kg°C).
• What does $m$ represent in the thermal energy formula?


  $m$ represents the mass, in kilograms (kg).
• What does $\Delta T$ represent in the thermal energy formula?


  $\Delta T$ represents the temperature change, in degrees Celsius (°C).
• What is specific latent heat?

  Specific latent heat is the amount of energy needed to change the state of 1kg of a substance without a change in temperature.
• What is the specific latent heat of fusion?

  The specific latent heat of fusion is the energy required to melt or freeze a substance.
• What is the specific latent heat of vaporisation?

  The specific latent heat of vaporisation is the energy required to boil or condense a substance.
• What is the formula for energy during a change of state?

  The formula for energy during a change of state is $E =$$m \times L$.
• What does $E$ represent in the change of state formula?


  $E$ represents the energy in joules (J).
• What does $m$ represent in the change of state formula?


  $m$ represents the mass in kilograms (kg).
• What does $L$ represent in the change of state formula?


  $L$ represents the specific latent heat in joules per kilogram (J/kg).
• What happens to energy when a substance melts or evaporates?

  Energy is absorbed when melting and evaporating.
• What happens to energy when a substance freezes or condenses?

  Energy is released when freezing and condensing.
• What is sublimation?

  Sublimation is when a solid goes straight to gas.
• What does the temperature graph of ice illustrate?

  • At point A: Ice is solid.
  • At point B: Ice reaches 0°C.
  • From B to C: No temperature change due to melting.
  • From C to D: Water is in liquid state.
  • From D to E: Water is boiling.
  • From E to F: Gas is heating.

  
• How are gas molecules related to temperature and kinetic energy?

  The temperature of a gas is related to the average kinetic energy of the molecules.
• What happens to the average speed of gas molecules as temperature increases?

  As temperature increases, the average speed of gas molecules also increases.
• What is gas pressure related to?

  Gas pressure is related to the total force exerted by all molecules inside the container on a unit area of the walls.
• What happens to gas pressure when the temperature of a gas is changed at constant volume?

  Changing the temperature of a gas at constant volume changes the pressure exerted by the gas.
• How does changing the volume of a gas affect its pressure?

  Changing the volume of a gas affects its pressure.