If an atom contains 12 protons and 10 neutrons, what's its mass number?

1 Answer
Aug 15, 2016

That atom, which is magnesium, has a mass number of 22


Let's use the diagram below:

To determine the mass number of an atom all you have to do is add the number of protons and the number of neutrons together.

In this case, the mass number is 22 because #10+12=22#