Chemical reactions are a rearrangement of rearrangement of electrons and how they are held between atoms.
To help us see this rearrangement, we define the oxidation state for each atom and see if it changes as a result of the reaction
Oxidation State
Oxidation state assumes that any shared electrons in a bond automatically exist in the orbitals of the more electronegative element. Oxidation states will need to be balanced on both sides of an equation.
The fact that the oxidation states changed int he formation of water can be thought of as each hydrogen atom giving up 1 electron and each oxygen atom accepting 2 electrons
We call reactions where the oxidation states change redox reactions
OILRIG
Oxidation it Loses (electrons) Reduction it Gains (electrons)
Split it into half reactions of oxidization and reduction then combine them back together
7 Step Algorithm
- split the equation
- balance all atoms except for H and O
- Balance O
- Balance H
- Balance charge using electrons (add)
- Equalize electrons
- Add and cancel