Introduce the units of atomic mass measurement as the Dalton and/or the Atomic mass unit. Relate how atomic mass is a quantitative measurement calculated from the number of atoms of elements in a substance, and the mass of those elements in AMU's. Define and discuss Avogadro's number, the mole, and the number 6.02 X 10^23. Discuss and review why the atomic numbers are not whole numbers but calculated based on the isotopes of the element and the percentage of isotopes for each element. Determine how many grams are contained in one mole of water, using AMU,s listed on the periodic table