1. Why is amu/atom = g/mole

2. Avogadro’s Number and the Mole
1 mol carbon = 12 g and 1 mol carbon = x 1023 atoms
So 12 g = x 1023 atoms
So for carbon the mass of 1 atom = 12 g / x 1023 atoms = 1.99 x g
If we divide the mass of one atom of carbon by 12 to get the mass of 1 amu
= 1.99 x g / 12 = 1.66 x 10 – 24 g = 1 amu
This relationship can be used as a conversion factor between amu and grams. The 1 is an exact value here because neither the 12 amu nor the 1 2 g were measured.
We will use this on the next slide
Very close to the mass of a proton/neutron (nucleon)

3. Why is it that atomic mass (amu/atom) = molar mass (g/mole)?
Has to do with the definition of amu and mole (which are related)
1. Amu = mass of 1/12 atom of C – x 10 – 24 g/amu
2. Mole = # of atoms in 12 g of C – x 1023 atoms/mole