A molecule is several atoms bonded together. For example, hydrogen (H) and Oxygen (O) are atoms, but H20 (two hydrogen and one oxygen) is a molecule. A mole is simply a number. It is 6.02214×10^23. A mole of hydrogen atoms means that there are 6.02214×10^23 hydrogen atoms. Molar Mass is the mass of 6.02214×10^23 of something. read more