The SI unit for amount of substance is the mole. It has the unit symbol mol. <span>The mole is defined as the amount of substance that contains an equal number of elementary entities as there are atoms in 12g of the </span>isotope carbon-12<span>.</span>
I don't know if it is organized by reactivity
it is organized by families
it is organized by atomic number
it is NOT organized by atomic mass
it is organized by periods and groups
