What is atomicity ?

The number of atoms present in a single molecule is termed as its atomicity. It can be classified into three types.

• The molecules of many elements are composed of only a single atom of that element. They are termed as monoatomic. For instance, Ar (Argon), He(Helium). So their atomicity is one.
• On the other hand the molecules of many elements are composed of two atoms of that element. For instance, oxygen can never exist independently and exist as O₂ molecule known as diatomic So its atomicity is 2.
• The molecules of many elements are composed of three atoms of that element. They are termed as triatomic For instance, O₃, CO₂. So their atomicity is 3.
• The molecules of many elements are composed of four atoms of that element. They are termed as tetra atomic For instance, P₄, SO₃. So their atomicity is 4.