Atomic Mass Unit: An atom is the smallest particle that can take part in a chemical reaction. It is so small and so light that it cannot be weighed by any laboratory balance. For instance, the masses of hydrogen, oxygen and silver atoms are 0.1673 X 10-23 g, 2.657 X 10-23 g and 17.9 X 10-23 g, respectively. This indicates that gram is too big a unit to weigh an atom and hence to express the weight of an atom in gram is unreasonable. It has, however, been found convenient to express the masses of atoms in terms of a … Continue reading Atomic Mass Unit