Oxidation States (and Ionic Charges)

Uncombined elements oxidation number

0

Oxidation number for atoms in molecules bonded to identical atoms

0

Monatomic ion oxidation number

Equal to its charge (e.g., Fe³⁺ = +3)

In a molecular ion, the sum of oxidation numbers

Equals the overall charge (e.g., SO₄^2- sums to -2)

In a neutral compound, the sum of oxidation numbers

Is 0 (e.g., Al₂O₃ sums to 0)

oxidation state of group 1

+1

oxidation state of group 2

+2

oxidation state of group 3

+3

oxidation state of oxygen (usually)

-2

oxidation state of oxygen in hydrogen peroxide

-1

oxidation state of oxygen when bonded to fluorine

+2

oxidation state of fluorine

-1

oxidation state of chlorine (usually)

-1

oxidation state of chlorine with oxygen or fluorine

positive

oxidation state of hydrogen (usually)

+1

oxidation state of hydrogen in metal hydrides

-1

nitrate ion charge

NO₃^-

carbonate

CO₃^2-

hydroxide

OH^-

ammonium

NH₄⁺

zinc

+2

silver

+1