The video describes the fundametnal mass relationships between the electron, proton and neutron. It is convenient to define an average mass of a nucleon that is valid across the periodic table. This atomic mass unit will be used for any conversion from atomic units to grams (and therefore kilograms). The inverse of the atomic mass unit is the number of amu in one gram. It is a measurement of how many atoms or molecules have a mass in grams equal to their atomic/molecular mass. It is therefore a constant for all atoms and molecules, and we call it Avogadro's number. Avogadro made a contribution to be sure, but his name sounds so appealing that we use this name extensively in chemistry. It is a crucial concept since we define Avogadro's number molecules as a unit, the mole. A mole is large enough that we usually
