oxidation number
The oxidation of free elements is zero.
The oxidation of simple ions is equal to their charge.
Some elements have fixed oxidation numbers
- Main group metals have oxidation number equal to their valency
- H is oxidation of +1 when it forms with non-metals and -1 in metal hydrides like NaH and
- In a molecule that is not pure oxygen, oxygen has oxidation of -2, except in is +2 and in some other is -1.
- Flouride is -1
- Sum of oxidation numbers in a neutral molecule is zero.
- Sum of oxidation numbers in a polyatomic ion is the charge on the ion.
very complex
Balancing complex half equations
Mn2+ +BiO_3- to Bi3+ + MnO_4-
Balance unique atoms (anything not oxygens and hydrogens)
4H_2O + Mn2+ to MnO_4- +8H+
Balance oxygens using water
4H_2O + Mn2+ to MnO_4-
Balance hydrogens using protons
add random hydrogens
4H_2O + Mn2+ to MnO_4- +8H+
Balance charges using electrons
add random electrons
4H_2O + Mn2+ to MnO_4- +8H+ + 5e-
Balance unique atoms (anything not oxygens and hydrogens)
BiO_3- to Bi^3+
Balance oxygens using water
BiO_3- to Bi^3+ + 3H_2O
Balance hydrogens using protons
add random hydrogens
6H+ + BiO_3- to Bi^3+ + 3H_2O
Balance charges using electrons
add random electrons
2e- + 6H+ + BiO_3- to Bi^3+ + 3H_2O