Question

give definition of a molecule state two important difference between an atom and the molecule

Answer 1

Group of atoms is called a molecules .
The main difference between an atom and molecules are:
1)Atoms may or may not exist in free state whereas Molecules are exist in free state.
2)Atoms are neither see with naked eyes nor magnifying microscope whereas Molecules are not seen by naked eyes but it can be seen by magnifying microscope.