Question

Name a gas that is monoatomic.

Answer 1

A gas that is monoatomic is :

• $\mathrm{Helium}\left[\mathrm{He}\right]$:
• Helium is categorised as monoatomic because it has only one atom in its molecule, whereas hydrogen (${\mathrm{H}}_2$) has two atoms in its molecule and is classified as diatomic.
• It is a member of the noble gases which means it has a filled outer shell of electrons. With a full outer shell, it doesn’t take part in most chemical reactions without a lot of force.