Hi everyone,
I'm trying to develop a resource that would allow my students to determine Avogadro's number from first principles, but all is not going to plan. My understanding is that Avogadro's number is the constant that enables a substance's molar mass in grams to equal its relative mass. To that end, I thought I could get my students to divide the relative mass of different elements by the actual mass of a single atom of each respective element. For example, Carbon 12 would be 12/2.0090761x10-23g. The numbers for oxygen, nitrogen, hydrogen and carbon consistently come out at 5x1021 lower than Avogadro's number (5.98x1023). I dimly recall someone mentioning that the actual mass of sub-atomic particles varies depending on the element because of relativistic effects. Is that what's going wrong?
Thanks