what are polyatomic ions class 9
Polyatomic ions are groups of two or more atoms that are chemically bonded together and carry a net electric charge. These atoms act as a single unit during chemical reactions.
A polyatomic ion can have either a positive charge or a negative charge.
Common examples of polyatomic ions
| Polyatomic Ion | Formula | Charge |
|---|---|---|
| Ammonium | NH4+ |
+1 |
| Hydroxide | OH− |
−1 |
| Nitrate | NO3− |
−1 |
| Sulphate | SO4²− |
−2 |
| Carbonate | CO3²− |
−2 |
Important points
They behave like a single ion in reactions.
They are found in many salts and compounds.
The atoms inside the ion remain bonded together.
For example, in sodium sulphate (Na2SO4), the sulphate ion (SO4²−) is a polyatomic ion. Polyatomic ions are important in chemistry because they help form many useful chemical compounds.