What is a polyatomic ion ? Give an example.

• Atoms that become charged by losing or gaining electrons are called ions.
• By donating electrons, the atom will form a positively charged ion known as a cation.
• By accepting electrons, the atom will form a negatively charged ion is known as an anion.
• Ions are two types simple ions and polyatomic ions.
• Simple ions consist of only one atom. For example, ${\mathrm{Na}}^{+}$ions formed from a single $\mathrm{Na}$atom.
• Polyatomic ions are ions that consist of more than one atom and carry an overall charge.
• For example $\mathrm{Phosphate}\left({{\mathrm{PO}}_4}^{3-}\right)$ consist of one $\mathrm{Phopshorous}$ and 3 $\mathrm{Oxygen}$ atoms and carry overall negative charge.
• The atoms in polyatomic ions are covalently bonded together. Therefore, they stay as a single charged unit.