Question

If an element contains 12 positively charged, massive particles, then what is the element? Why is the atomic mass NOT equal to `12*"amu"`?

Answer 1

Well, if there are 12 nucular protons, then we gots magnesium isotopes....

Explanation:

Why? Because `Z=12` gives the element magnesium by definition. And magnesium has several isotopes....we could write...`""^24Mg`, `""^25Mg`, `""^26Mg`, which occur naturally in approx. `80%`, `10%`, `10%`, natural abundance.. And of course, the weighted average, `24.31*g*mol^-1`, is the mass we would use for the metal were we to use it as a reagent. `Mg^(2+)` is the standard cation....