Topic 3 - Particle model of matter

Equation to calculate density

Mass/volume

States of matter

• Solid particles are tightly compacked and the bonds between the particles are very strong, solids vibrate and have a high density

• Liquid particles are tightly compacked but can move around eachother. They have a medium density

• Gas particles can move all around the space, they have week bonds between particles and they have a very low density

Experiment to measure the density of a solid liquid

Experiment to measure the density of a liquid

Experiment to measure the density of an irregular object

The changes of state

Freezing = liquid-solid

Melting = solid-liquid

Sublimation = solid-gas

Deposition = gas-solid

Condensing = gas-liquid

Evaporating = liquid-gas

What happens to the mass of a substance when it changes state

Mass is conserved

Changes when mass is conserved

If mass is conserved and the volume changes, the density will also change

Explain why a change of state is different to a chemical change

These physical changes are reversible, and not chemical changes

• They are not chemical because the material retains its original properties when reversed

Describe where energy is stored inside a system

Chemical:

• Anything that can release energy by chemical reaction, eg Food, fuels, chemicals found in batteries

Kinetic:

• Anything moving has energy in its kinetic energy store

Thermal:

• Any object. The hotter it is, the more energy it has in this store. You may also see thermal energy stores called internal energy stores

Gravitational potential:

• Anything that has mass and is inside a gravitational field

Elastic potential:

• Anything that is stretched (or compressed) eg springs

Electrostatic:

• Anything with elastic charge that is interacting with another electric charge eg two charges that attract or repel each other

Magnetic:

• Anything magnetic that is interacting with another magnet eg two magnets that attract or repel each other

Nuclear:

• Atomic nuclei have energy in this store that can be released in nuclear reactions

Internal energy definition

• Energy which is stored by particles (atoms and molecules) within a system the energy takes the forms of:

• Kinetic Energy (vibration of atoms etc.)

• Potential Energy (between the particles)

Explain how heating affects the energy stored within a system and the effects that heating can have on a  system

• Heating increases the energy the particles have

• This increases the internal energy

• This either raises the temperature of the system

• Or produces a change of state