Question

Define atomicity with examples.

Answer 1

the number of atoms present in an element is called the atomicity of an element ...
Here some examples are Monoatomic molecules Gold, Helium, and Neon. While Diatomic molecules Hydrogen, Oxygen and Hydrogen chloride. 
 i hope it helps...

Answer 2

Atomicity is the number of atoms of an element present in one molecule of that element. For example, there are 2 atoms of hydrogen present in H2 molecule so it atomicity is 2.