| Atoms | Molecules |
| Most fundamental and smallest part that can exist of an element. | Two or more atoms chemically bonded together. |
| Example : Oxygen – O Phosphorus – P Sulphur – S Hydrogen – H | Example : Oxygen – O2 Phosphorus – P4 Sulphur – S8 Water – H2O |
| Smallest particle with properties of an element. | Combination of two or more atoms. |
| An atom may not always be stable in nature due to the presence of electrons in the outer shells. | Molecules are formed to attain stability. |
| Protons, Electrons & Neutrons | Two or more atoms of the same or different elements |
| Except for the noble elements, atoms of all elements showcase a certain level of reactivity. | Compared to a molecule, the level of reactivity is less as some of the valence points are filled by electrons of combined elements. |
