ICSE Class 6 Answered

                                               Atom

                                                Molecule

It is a smallest particle of an element.

It is a group of two or more atoms combined together.

It consists of nucleus (containing protons and neutrons) and electrons.

It consists of combination of two or more, same or different atoms chemically bound together. e.g. H₂, HCl, NaCl etc.

It can neither be seen through naked eye nor through magnifying microscope.

It is not visible to naked eye, while can be seen through highly magnifying microscope.

It cannot be further divided.

It can further be divided to give individual atoms.

It may or may not have independent existence.

They are capable of having independent existence. 
For example, atom of oxygen (O) has no independent existence but its molecule exists as O₂ in nature.

It has nuclear bond or attraction within it i.e. it involves electrostatic attraction between the positive nucleus and electrons.

It has chemical attraction or bonding between the atoms i.e. it involves single, double or triple bonds between the atoms.