Common Polyatomic and Simple Monatomic Ions—Formulas & Charges

Vocabulary flashcards covering 45 essential polyatomic and monatomic ions, with each card listing the ion’s common name and its chemical formula / charge.

Mercury(I) ion

Hg₂²⁺ (diatomic mercury cation with +2 total charge)

Ammonium ion

NH₄⁺ (polyatomic cation with +1 charge)

Nitrite ion

NO₂⁻ (polyatomic anion with −1 charge)

Nitrate ion

NO₃⁻ (polyatomic anion with −1 charge)

Sulfite ion

SO₃²⁻ (polyatomic anion with −2 charge)

Sulfate ion

SO₄²⁻ (polyatomic anion with −2 charge)

Hydrogen sulfate (bisulfate) ion

HSO₄⁻ (polyatomic anion with −1 charge)

Hydroxide ion

OH⁻ (polyatomic anion with −1 charge)

Cyanide ion

CN⁻ (polyatomic anion with −1 charge)

Phosphate ion

PO₄³⁻ (polyatomic anion with −3 charge)

Hydrogen phosphate ion

HPO₄²⁻ (polyatomic anion with −2 charge)

Dihydrogen phosphate ion

H₂PO₄⁻ (polyatomic anion with −1 charge)

Thiocyanate ion

SCN⁻ / NCS⁻ (polyatomic anion with −1 charge)

Carbonate ion

CO₃²⁻ (polyatomic anion with −2 charge)

Hydrogen carbonate (bicarbonate) ion

HCO₃⁻ (polyatomic anion with −1 charge)

Hypochlorite ion

ClO⁻ / OCl⁻ (polyatomic anion with −1 charge)

Chlorite ion

ClO₂⁻ (polyatomic anion with −1 charge)

Chlorate ion

ClO₃⁻ (polyatomic anion with −1 charge)

Perchlorate ion

ClO₄⁻ (polyatomic anion with −1 charge)

Acetate ion

C₂H₃O₂⁻ (polyatomic anion with −1 charge)

Permanganate ion

MnO₄⁻ (polyatomic anion with −1 charge)

Dichromate ion

Cr₂O₇²⁻ (polyatomic anion with −2 charge)

Chromate ion

CrO₄²⁻ (polyatomic anion with −2 charge)

Peroxide ion

O₂²⁻ (polyatomic anion with −2 charge)

Oxalate ion

C₂O₄²⁻ (polyatomic anion with −2 charge)

Thiosulfate ion

S₂O₃²⁻ (polyatomic anion with −2 charge)

Hydrogen ion

H⁺ (monatomic cation with +1 charge)

Lithium ion

Li⁺ (monatomic cation with +1 charge)

Sodium ion

Na⁺ (monatomic cation with +1 charge)

Potassium ion

K⁺ (monatomic cation with +1 charge)

Cesium ion

Cs⁺ (monatomic cation with +1 charge)

Beryllium ion

Be²⁺ (monatomic cation with +2 charge)

Magnesium ion

Mg²⁺ (monatomic cation with +2 charge)

Calcium ion

Ca²⁺ (monatomic cation with +2 charge)

Barium ion

Ba²⁺ (monatomic cation with +2 charge)

Aluminum ion

Al³⁺ (monatomic cation with +3 charge)

Hydride ion

H⁻ (monatomic anion with −1 charge)

Fluoride ion

F⁻ (monatomic anion with −1 charge)

Chloride ion

Cl⁻ (monatomic anion with −1 charge)

Bromide ion

Br⁻ (monatomic anion with −1 charge)

Iodide ion

I⁻ (monatomic anion with −1 charge)

Oxide ion

O²⁻ (monatomic anion with −2 charge)

Sulfide ion

S²⁻ (monatomic anion with −2 charge)

Nitride ion

N³⁻ (monatomic anion with −3 charge)

Phosphide ion

P³⁻ (monatomic anion with −3 charge)