physics 1 particles

• What is meant by the particle theory

  Helps to explain how the particles behave
• How are particles considered

  A small

  Inelastic

  Sphere
• How are solids arranged?

  In a regular lattice structure close together

  in a fixed shape and volume (doesn't flow)

  Can vibrate (like when heated)
• What happens when we heat a solid?

  Particles gain kinetic energy and they start to vibrate

  The vibrations weakens the forces between them
• What happens when a solid reaches it's melting point

  The particles will have enough energy to break free of their bonds

  Solid melts into a liquid
• What is meant by bonds?


  The forces of attraction between particles
• properties of liquid


  Weak forces of attraction between them

  Free to move around

  Arranged randomly
• What enables a liquid to fit into a container?

  the particles stick together and are fairly compact (definite volume)

  Means the shape can change therefore can flow to fit a container
• What happens when we heat a liquid

  Particles gain more kinetic energy

  Makes the particles move around faster so weakens the forces
• What happens when a liquid reaches its boiling point

  Particles have enough energy to break the bonds

  Liquid evaporates into a gas
• What happens when we cool down a liquid

  Particles don't have enough energy to overcome attraction

  Means more bonds form and fixes the particles into place

  Freezing the liquid into a solid.
• properties of gas


  Forces of attraction are very weak

  Particles move around freely

  Don't keep definite shape or volume
• Why do gases always fill a container

  The particles spread out
• How do gases move


  Move within random motion but are deflected by solid surfaces
• What happens when we heat a gas

  Particles gain more kinetic energy

  Means they travel faster

  In a expandable container the particles can expand

  In a fixed container the pressure will increase
• What happens when we cool a gas down?

  Particles don't have enough kinetic energy to overcome forces of attraction

  Bonds start to form

  Condense into a liquid
• Why doesn't the mass change when changing state?

  As there is the same amount of particles
• Describe density of all three stares

  Solid- highest density

  Liquid- slightly lower

  Gas- lowest
• How to calculate density

  mass divided by volume

  (d=m/v)
• What is density?


  How much Mass a substance has per unit volume
• How to convert g/cm^3 to kg/m^3

  multiply by 1000
• How do you find a mass of a solid

  Place solid on a balance

  Measure the mass
• How to find the volume of a solid

  length x width x height

  Or

  Use a eureka can and measure the ammount of water that has filled the measuring cylinder
• How to find the mass of a liquid

  Place empty measuring cylinder on to balance and zero the reading

  Record mass
• How to find the volume of a liquid


  Pour liquid into measuring cylinder

  xml= xcm^3
• How can you make the volume reading more accurate

  Find mean

  Use a larger volume of the liquid to minimise effects of uncertainty
• What happens to a substance as we heat it?

  The particles gain internal energy in the kinetic energy stores

  Meaning the temperature increases
• What is temperature?


  The measure of the average kinetic energy (internal energy) of the substances
• Why does the temperature remain constant when changing state (heating)

  When a substance is changing state (MP, BP)

  The energy which is being provided is being used to weaken or break the forces being held together

  Instead of increasing the particles internal energy

  So the temperature won't change until all of the substance has changed state
• Why does the temperature remain constant when changing state (cooling)

  Same principle

  State change involves the formation of new bonds between the particles

  Which releases energy

  This counteracts with the cooling and is what keeps the temperature constant when changing state
• What does latent heat depend on?

  the type of substance and the amount of substance
• What is specific latent heat?

  The amount of energy required to change 1kg of a particular substance from one state to another.

  (For cooling is the amount of energy released)
• Specific latent heat of vaporisation

  Energy change when a substance changed between a LIQUID and GAS

  (Evaporate or condense)
• Specific latent heat of fusion

  Energy change when a substance changes between a SOLID and LIQUID

  (Melts or freezes)
• What the equation for specific latent heat?

  Energy required or released= mass X SLH

  E= m X L
• What causes pressure in a container

  Collisions of particles against the wall of the container.

  The particles exert a force
• What is pressure?


  Force exerted per unit area.
• What's the equation for pressure

  Pressure= force/ area
• What does the total pressure depend on?

  How many collisions there are

  How much each collision involves
• What affect does temperature have on pressure

  When we heat the particles there kinetic energy increases meaning they move around faster.

  There are more collisions and each collision has more force.

  Pressure increases with temp