<span>The answer is 62 u. The molecular mass of a molecule (Mr) is the sum of atomic masses (Ar) of its elements. Ar(Na) = 23 u. Ar(O) = 16 u. Therefore, the molecular mass of sodium oxide is 62 u: Mr(Na2O) = 2 * Ar(Na) + Ar(O) = 2 * 23 u + 16 u = 46 + 16 = 62 u.</span>
The superscripts in a chemical formula are the overall charge of an ion
C difference in temperature
-- all electrons are identical
-- electrons have a negative electrical charge
-- the size of the charge is equal to the positive charge on a proton
-- but it takes about 1,840 electrons to make the mass of one proton
