Here's a breakdown:
* -ite: This ending generally indicates a lower oxidation state of the central nonmetal atom. For example, in sulfite (SO₃²⁻), sulfur has an oxidation state of +4, compared to +6 in sulfate (SO₄²⁻).
* -ate: This ending generally indicates a higher oxidation state of the central nonmetal atom. For example, in nitrate (NO₃⁻), nitrogen has an oxidation state of +5, compared to +3 in nitrite (NO₂⁻).
Here are some examples:
* Sulfite (SO₃²⁻) vs. Sulfate (SO₄²⁻)
* Nitrite (NO₂⁻) vs. Nitrate (NO₃⁻)
* Phosphate (PO₄³⁻) vs. Phosphite (PO₃³⁻)
* Carbonate (CO₃²⁻) vs. Carbonite (CO₂²⁻) (Note: carbonite is not a common ion)
Exceptions:
There are some exceptions to this rule, but the majority of polyatomic ions follow this pattern. For example, perchlorate (ClO₄⁻) has a higher oxidation state of +7 for chlorine, even though it ends in "-ate".
Important Note: This distinction is often a helpful way to remember the formulas and names of common polyatomic ions. It is not a strict rule, but it is a useful generalization.
