Monoatomic Ions:
* Mono means "one."
* Atomic refers to atoms.
* Ions are atoms or groups of atoms that carry a net electric charge.
Therefore, monoatomic ions are ions composed of only one atom. Examples include:
* Cations: Na+, K+, Ca2+, Fe3+, etc.
* Anions: Cl-, Br-, O2-, S2-, etc.
Polyatomic Ions:
* Poly means "many."
* Atomic refers to atoms.
* Ions are atoms or groups of atoms that carry a net electric charge.
Polyatomic ions are ions composed of two or more atoms bonded together. They act as a single unit and carry a charge. Examples include:
* Anions: NO3- (nitrate), SO42- (sulfate), PO43- (phosphate), CO32- (carbonate), etc.
* Cations: NH4+ (ammonium), H3O+ (hydronium), etc.
Naming Monoatomic Ions:
* Cations (positive ions): The name of the element is used. For example, Na+ is sodium ion, K+ is potassium ion, etc. If the element has multiple possible charges, the charge is indicated in Roman numerals in parentheses after the element name. For example, Fe2+ is iron(II) ion, and Fe3+ is iron(III) ion.
* Anions (negative ions): The name of the element is changed to end in "-ide." For example, Cl- is chloride ion, Br- is bromide ion, etc.
Naming Polyatomic Ions:
* Polyatomic ions have specific names that you need to memorize. There are no systematic rules for naming them like with monoatomic ions.
In summary:
* Monoatomic ions are single atoms with a charge.
* Polyatomic ions are groups of atoms bonded together with a charge.
