Give an example of an ion which is mono-atomic.

Monoatomic Ion

1. A monoatomic ion is an ion consisting of exactly one atom.
2. The charge on the ion is the difference between the number of protons and electrons.
3. If there are more protons, the charge is positive and if there is an excess of negative ions, the charge is negative.
4. Examples: potassium chloride $\left(\mathrm{KCl}\right)$ dissociates in water into ${\mathrm{K}}^{+}$and ${\mathrm{Cl}}^{-}$ ions, both of these are monoatomic. Hydrogen usually forms a monoatomic ion ${\mathrm{H}}^{+}$.

Therefore, the example of a monoatomic ion is sodium $\left({\mathrm{Na}}^{+}\right)$, as sodium chloride (NaCl) dissociates into ${\mathrm{Na}}^{+}\mathrm{and}{\mathrm{Cl}}^{-}$ ions.