a) Atomicity : The number of atoms constituting a molecule is known as its atomicity.
Ex :
1) Na is monoatomic
2) O2 is diatomic
3) O3 is triatomic
b) Valency : Atoms of the elements have power to combine with atoms of other elements. This is known as valency.
Ex :
1) Valency of carbon is 4.
2) Valency of oxygen is 2.
3) Valency of hydrogen is 1.
c) Ions:
1) Ions may be a single charged atoms or a group of atoms that have a net charge on them.
2) A negatively charged ion is called anion and the positive charge ion is cation.
Ex : Na+, Cu+2, S2-, N3-, etc.
