1. atom is the smallest particle of an element.
2. atom may or may not have independent existence.
3.atoms consists of nucleus (containing protons and neutrons) and electrons.
4. atom has nuclear bond of attraction.

1. molecule is a group of two or more atoms combined together
2.molecules consists of two or more similar or different atoms chemically bounded together.
3.molecules are capable of having independent existence.
4.molecules have chemical bond or attraction between the atoms. 
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