CHEM 101 - Polyatomic Ions and Oxidation States

Oxidation state of elements? (ex. Cl₂, Na)

0

Oxidation state of monatomic ions? (ex. Ca²⁺)

Equal to charge

Oxidation state of ions in a neutral compound?

Oxidation states of compound adds to zero, subtract to find the state of the ion

Oxidation state of ions in a polyatomic ion?

Oxidation states of compound adds to charge on polyatomic ion, subtract to find the state of the ion

Oxidation state of hydrogen?

+1 in combination with nonmetals, -1 in combination with metals and boron

Oxidation state of oxygen?

-2 in most cases, unless in a peroxide (-1), superoxide (-1/2), or a more electronegative atom (in F, +1)

Ammonium

NH₄⁺

Nitrite

NO₂^-

Nitrate

NO₃^-

Sulfite

SO₃^2-

Sulfate

SO₄^2-

Hydrogen sulfate

HSO₄^-

Hydroxide

OH^-

Cyanide

CN^-

Phosphite

PO₃^3-

Phosphate

PO₄^3-

Hydrogen phosphate

HPO₄^2-

Dihydrogen phosphate

H₂PO₄^2-

Carbonate

CO₃^2-

Hydrogen carbonate

HCO₃^-

Hypochlorite

ClO^-

Chlorite

ClO₂^-

Chlorate

ClO₃^-

Perchlorate

ClO₄^-

Permanganate

MnO₄^-

DIchromate

Cr₂O₇^2-

Chromate

CrO₄^2-

Peroxide

O₂^2-

Acetate

CH₃COO^-

Superoxide

O₂^-

Hypoiodate

IO^-

Periodate

IO₄^-

Iodite

IO₂^-

Iodate

IO₃^-

BrO^-

Hypobromite

Bromite

BrO₂^-

Bromate

BrO₃^-

Perbromate

BrO₄^-

Aluminum

Al³⁺

Mercury

Hg₂²⁺