Calculate the mass defect (deficit) in amu/atom.

Question

An atom of ⁷⁵Ga has a mass of 74.926500 amu.

1. mass of¹H atom = 1.007825 amu
2. mass of a neutron = 1.008665 amu

Answer 1

So Elva V.,

You have a periodic table in front of you? Figure the protons and neutrons in 75Ga. Then just do the math for that number of H atoms (for the protons, and their matching electrons!) and the neutrons. Add 'em up, compare to the stated 75Ga atom.

Now the $64,000 question (that's after an old TV quiz show, that built eventually to that question value): what does the binding energy (that's what you just calculated) actually DO in the atom? Note that it is a negative amount of energy, just like electrons on an atom have negative energy vs. jumping off (to leave behind an ion) and wandering freely away in space.

--Cheers, Mr. d.