PARTICLE MODEL

• what is density?


  how compact something is
• what is the formula for density?


  density = mass / volume
• what are the properties of solids?


  - strong forces of attraction

  - fixed, regular arrangement

  - vibrate about fixed positions
• what are the properties of liquids?


  - weaker forces of attraction

  - irregular arrangement

  - random directions at low speeds
• what are the properties of gases?

  - no forces of attraction

  - free to move;

  - random directions at high speeds
• what is a change of state?


  a physical change of a substance from one state to another
• why is a change in state a physical change?


  - mass is conserved

  - the material recovers its original properties if the change is reversed
• what is internal energy?


  the total kinetic energy and potential energy of all the particles that make up a system
• how does heating change the energy stored within a system?


  the internal energy increases
• what does the increase in temperature of a system depend on?


  - mass of the substance heated

  - type of material

  - energy input to the system
• what is the formula for change in thermal energy?

  change in thermal energy = mass × specific heat capacity × temperature change
• what is specific heat capacity?


  the amount of energy required to raise the temperature of one kilogram of the substance by one degree celsius
• what is specific latent heat?


  the amount of energy required to change the state of one kilogram of the substance with no change in temperature
• what is specific latent heat of fusion?


  the change of state from a solid to a liquid
• what is specific latent heat of vaporization?


  the change of state from a liquid to a vapor
• what is the particle motion in a gas?

  constant random motion
• what is the temperature of a gas related to?

  the average kinetic energy of the molecules
• what happens when you change the temperature of a gas?

  at a constant volume, it changes the pressure exerted by the gas
• how does a gas exert pressure on a surface?

  when molecules collide with a surface they produce a net force at right angles to the surface
• what is the outward gas pressure?


  the total force exerted by all of the particles in the gas on a unit area of the container walls
• what is the relationship of pressure and volume in a gas?


  pressure × volume = constant

  p × V = constant
• why does the temperature of a gas increase when it is compressed quickly enough?


  doing work on a gas can increase its temperature by increasing its internal energy
• describe and explain how the pressure inside and outside of a balloon would change if it were allowed to float up the atmosphere


  - pressure decreases with height, so pressure outside the balloon will decrease

  - This will cause the balloon to expand until the pressure inside and outside are equal