Atom | Molecule |
Atoms may or may not exist freely depending upon their valency. | All molecules can exist freely. |
An atom is the smallest particle in an element that has all the properties of the element. It is not possible to further breakdown an atom through chemical means. | Molecules may or may not be classified as smallest particles of matter depending upon whether they are monatomic or not. Molecules can be subdivided to individual atoms by chemical processes. |
Atoms cannot be seen through naked eye or through high-resolution microscope. They can be observed only with an electron microscope. | Molecules cannot be seen through naked eye but can be seen through high-resolution microscope. |
Atoms are made up of electrons, protons and neurons. | Molecules are made up of atoms of same or different elements. |
Example: N, O, Fe, H | Example: N2, H2, H2O, He |