Question

why do atom is less stable than molecules?

Answer 1

it is because  melecules are made up of many atoms and atom is a single unit.thats why atom is less stable that molecules.

Answer 2

atoms are less stable as they may or maynot have a complete outer shell..or in other words they dont hav 8 electrons in the outer shell..bt in case of molecules the atome form respective bonds to cmplete their individual outer shells and hence they are more stable