particle model of matter

• the density of a material is the mass for a given volume
• what is density

  mass of a given volume
• density = mass / volume
• p = m / v
• the unit of density is kg/m3
• solids and liquids have high densities because their particles are packed closely together
• why do solids and liquids have high densities

  the particles are packed closely together so they have a lot of mass for their volume
• particles have potential energy from cheical bonds
• internal energy is the total kinetic energy and potential energy of all the particles that make up a system
• what is internal energy

  total kinetic and potential energy of all particles in a system
• solid to a gas is called sublimation
• what is the change of state from solid to gas called

  sublimation
• what is specific heat capacity

  amount of energy required to raise the temp of 1kg of the substance by 1 degree
• change in thermal energy = mass x SHC x temp change
• what is the latent heat

  energy needed for a substance to change state but NOT the temp
• what is the specific latent heat

  amount of energy required to change the state of 1 kilogram of the substance with no change in temperature
• latent heat of fusion = amount of energy required to melt one kg of a substance without changing its temperature
• latent heat of vaporisation = amount of energy required to evaporate one kg of a liquid without changing its temperature
• energy for a change of state = mass x SLH
• particles in a gas are far apart
• what are particles in a gas like

  far apart
• particles in gases are in constant random motion
• pressure of a gas is due to the particles colliding with the walls of the container
• pressure in a gas is due to

  particles colliding with the walls of the container its in
• by colliding with the walls of the container the gases are exerting a pressure
• how can we increase the gas pressure

  increases number of collisions

  increase energy of each collision
• gas particle collisions cause a force which acts at right angles of the walls of the gas container
• the force acting over the area of the container causes gas pressure
• the pressure of a gas is inversely proportional the the volume
• pressure = force exerted over an area
• the greater the pressure the greater the force exerted over a area
• Mechanical work transfers energy from the person or machine’s store of chemical energy to the internal energy store of the gas.
• work done = force x distance
• temperature is a measure of the average kinetic energy