The Three States of Matter
- In a solid state molecules can barely move, as they are held together. They can only vibrate in place because the inter-particle forces are very strong.
- This is how solid objects retain their structure.
- As a solid is heated up the atoms begin to move more and thus lose their shape and become a liquid.
- Molecules can slide over each other and the substance can take the form of a container.
- In a gas the atoms can move freely due to the amount of heat and as the particle forces are very weak. The substance can fill up the container.
The Fourth State of Matter
- In plasma the nucleus still remains as per usual, however the atoms have lost their electrons as the electrons can move freely.
- Substances can only become plasma in extreme heat and pressure, like in the sun for instance.
States of Matter in Chemical Equations
- The states of the substance are marked with abbreviations
- The abbreviations are written in the reaction equation after the substance in brackets.
- (s) Solid
- (l) Liquid
- (g) Gas
- (aq) Aqueous solution
- For example: C(s) + O2(g) --> CO2(g)
Changes in Matter
- Substances can change states depending on the temperature.
- Melting is when a solid becomes a liquid.
- Evaporation is when a liquid becomes a gas in a slow process that occurs in moderate heat.
- Boiling is when a liquid becomes a gas due to reaching its boiling point.
- Vaporization is when a liquid or a solid becomes a gas.
- Sublimation is when a solid becomes a gas.
- Solidification is when a liquid becomes a solid.
- Condensation is when a gas becomes a liquid.
- Deposition is when a gas becomes a solid.
Endothermic and Exothermic Changes
- Melting, evaporation, boiling, vaporization and sublimination all need heat, thus they are endothermic.
- Solidification, condensation and deposition all release heat, and thus they are exothermic.
- Changes that occur due to high temperatures are endothermic, and changes that occur due to low temperatures are exothermic.