The formal charge of the sulfate ion, which has the molecular formula (SO4)2-, is -2. Ions that have a negative charge are called anions, and positively charged ions are called cations.
The sulfate ion has a two-dimensional structure, and its shape is tetrahedral. The bond angles between the four oxygen and sulfur atoms is 109.5 degrees.
The sulfate ion, which is a polyatomic ion, is found in different chemical compounds. These compounds include hydrogen sulfate, sodium hydrogen sulfate and ammonium sulfate. Hydrogen sulfate is also called sulfuric acid with the formula H2SO4. Sodium hydrogen sulfate is an acid salt, which is an ionic compound with the chemical formula NaHSO4.