Common Polyatomic Ions (gen chem)

Polyatomic ions Ions composed of 2 or more atoms

NH₄⁺ ammonium

Hg₂²⁺ mercury(I)

CN⁻ cyanide

O₂²⁻ peroxide

OH⁻ hydroxide

C₂H₃O₂⁻ acetate

NO₂⁻ nitrite

NO₃⁻ nitrate

MnO₄⁻ permanganate

ClO⁻ hypochlorite

ClO₂⁻ chlorite

ClO₃⁻ chlorate

ClO₄⁻ perchlorate

CO₃²⁻ carbonate

C₂O₄²⁻ oxalate

CrO₄²⁻ chromate

Cr₂O₇²⁻ dichromate

SO₃²⁻ sulfite

SO₄²⁻ sulfate

PO₄³⁻ phosphate

Halogen oxoanion pattern Replace Cl with any Group 17 halogen (F, Br, I). Same prefixes/suffixes apply.

Example: BrO⁻ hypobromite

Example: BrO₂⁻ bromite

Example: BrO₃⁻ bromate

Example: BrO₄⁻ perbromate

Most oxygen (4 O for Cl) per- + root + -ate → perchlorate ClO₄⁻

Next (3 O) root + -ate → chlorate ClO₃⁻

Next (2 O) root + -ite → chlorite ClO₂⁻

Least oxygen (1 O) hypo- + root + -ite → hypochlorite ClO⁻

Root for chlorine series chlor

Root for bromine series brom

Root for iodine series iod

Root for fluorine series fluor