Question

The sum of all percent abundances for magnesium is equal to 100. explain why this is reasonable.

Answer 1

All magnesium is divided in abundances.

Step-by-step explanation:

So the amount of magnesium that exists in the planet is finite, we have a 100% of magnesium, now as you know there are different isotopes that exists and when you divide that 100% in the different isotopes. it is logical that the sum of all the different abundances of magnesium is equal to the initial 100%.

Answer 2

Elements occur naturally in different forms called isotopes. These are the same atoms with the same number of protons but has different number of neutrons. Almost all elements exist in nature as such. The amounts of these isotopes are expressed in terms of percent abundances and since it is in a percentage units, the sum of all the abundances should equate to 100 percent or else the calculation is wrong. This is not true onlt for magnesiun but with all of the elements. The atomic mass of these elements also depends on the percent abundances of the isotopes since it is a weighted average value of the individual masses of the isotopes.