States of Matter

KEY POINTS:

• There are three (maybe four, possibly five) states of matter – solid, liquid and gas.
• Physical changes involve moving from one state of matter to another. They are relatively easy to do, and can be reversed.
• Physical changes only involve a rearrangement of the particles involved. The particles themselves do not change. For example:
  • ice is composed of H₂0 molecules in the solid arrangement,
  • water is composed of H₂0 molecules in the liquid arrangement, and
  • steam is composed of H₂0 molecules in the gaseous arrangement.
• The physical properties of the different states of matter are dictated by the arrangement of the particles.
• Remember – the forces of attraction between the particles will determine the physical properties.