Basis of differentiation

Atoms 

Molecules 

Definition 

Atoms are the smallest units of matter that still retain the characteristic properties of their element

Molecules are a combination of two or more atoms that are held together by chemical bonds

Components

An atom is made up of three subatomic particles – protons, neutrons, and electrons

A molecule is made up of two or more atoms, which can be of the same element or of different elements 

Stability

Atoms are not stable by themselves in nature due to the presence of electrons in the outer shells. They attain stability by forming chemical bonds with other atoms. 

Molecules are formed by atoms to attain stability. They are stable by themselves in nature. 

Separation 

Atoms cannot be separated into subatomic particles by chemical reactions. Separation is only possible by nuclear reactions.

Molecules can be separated into atoms by chemical reactions.

Reactivity

All atoms, except the noble elements, exhibit some amount of reactivity.

Molecules exhibit less reactivity than atoms. 

Examples 

Hydrogen (H)

Calcium (Ca)

Sodium (Na)

Chlorine (Cl)

Iron (Fe)

Water (H20)

Carbon dioxide (C02)

Glucose (C6H12O6 )

Table salt (NaCl)

Calcium Oxide (CaO)