A mole is approximately the number of protons in a gram of protons. The mass of a neutron is about the same as the mass of a proton, while the mass of an electron is usually negligible in comparison, so if you know the total number of protons and neutrons in a molecule (i.e., its “atomic mass”), you know the approximate mass (in grams) of a mole of these molecules. Referring to the periodic table at the back of this book, find the mass of a mole of each of the following: water, nitrogen (N2), lead, quartz (SiO2).
We know that
Atomic mass Number of protons + neutrons
Mass in grams of one mole of a substance
The approximately required atomic mass total number of proton + neutrons