The atomic mass of potassium is 39. If its atomic number is 19, how many neutrons are in each potassium atom?
1 Answer
Jun 14, 2016
20.
Explanation:
Protons (the atomic number) and neutrons both contribute to the atomic mass.
If you therefore subtract the number of protons (19) from the atomic mass (39), you are left with the number of neutrons (=20).