1.1.2 – The kinetic molecular theory
📌 Different states
- Matter exists in different states based on temperature
- Matter can convert between states depending on the temperature
- The kinetic theory of molecules using descriptions of kinetic energy to explain how particles in the three states move
| Â Solid | Â Liquid | Â Gas |
| particles vibrate around a lattice (strong forces) | particles flow over each other (weaker forces) |  particles are very spread out (very weak forces) |
| fixed shape | shape determined by container | Â no fixed shape |
| Â fixed volume | Â fixed volume | Â no fixed volume |
| Â closely packed | Â loosely packed | Â very loosely spread |
📌 Kinetic energy
- Kinetic energy is represented by the symbol Ek and refers to energy associated with motion
- The kinetic theory of molecules using descriptions of kinetic energy to explain how particles in the three states move
Ek = 0.5mv2 at a fixed temperature
The inverse relationship between mass and velocity here can be written as :
(m1/m2) = (v22 /v12)
📌 State symbols
- State symbols are used in equations to represent whether a reactant/product is in gaseous, liquid, aqueous or solid form
- Gaseous (g), liquid (l), aqueous (aq) and solid (s) are included in the equation as seen below :
2Na(s) + 2H2O(l) → 2NaOH(aq) + H2(g)
📌 Changes in states of matter
- Melting : solid to liquid, freezing : liquid to solid
- Boiling : liquid to gas, condensing : gas to liquid
- Deposition : gas to solid, sublimation : solid to gas