Chemical Amount?? Hey guys, I'm looking for a little help with the whole concept of chemical amount. This question was posed during my intro chem lecture (assume a hydrogen atom's mass is 1 amu, and an oxygen atom's mass is 16 amu): How much oxygen does one need, to have the same number of oxygen atoms as there are hydrogen atoms in one gram of hydrogen gas? The answer was said to be 16 grams, but I can't understand why. My professor said that the amount of grams was proportional to the amu's or something.