AP Chemistry OXIDATION NUMBERS RULES

Oxidation Numbers for PURE ELEMENTS ( O₂, Zn)

Always 0

Oxidation Numbers of IONS (Zn⁺²)

It is always the charge (Zn⁺² is 2 oxidation numbers)

Oxidation Numbers for F in Compound

-1, always because it is most electronegative!

Oxidation Numbers for Hydrogen (2 answers)

H = +1 when bonded to non metal, H = -1 when bonded to metal

Oxidation Numbers for OXIDE (CaO)

O = -2

Oxidation Numbers for Group 1 metals (Li, Na, K)

+1

Oxidation Numbers for Group 2 Metals (Mg, Ca, Ba)

+2

Sum of oxidation numbers In a neutral compound (H₂O)

Always 0

Sum of Oxidation Numbers in a polyatomic ion (SO₄^2-)

The Ion charge (SO₄^2- = -2 and S = +6 due to O = -2)

Oxidation Numbers Halogens Group 17 (Cl, Br, I)

-1 unless bonded to oxygen or fluorine