Whats the difference between atoms and molecules?
A molecule is smallest physical unit of an element or compound. Compounds are chemical combinations of different elements. A molecule of water is composed of two atoms of hydrogen combined with one atom of oxygen. Thus the smallest component in water that can still be called water is the molecule H2O which is composed of three atoms. On the other hand, even though gold forms cubic crystalline units containing 14 atoms, it still retains its identity as gold as a single atom. Thus a molecule of gold is composed of a single gold atom.
