Question

Complete the following:
Mercury (+2) ion contains 80 protons, 78 electrons, and 120 nucleons. Its mass number is ________.

Answer 1

Mass number:

1. The mass number is the total number of protons and neutrons present in an atom.
2. $\mathrm{Mass}\mathrm{number}=\mathrm{Number}\mathrm{of}\mathrm{protons}+\mathrm{Number}\mathrm{of}\mathrm{neutrons}$
3. Thus, it is also known as the “nucleon number”, as both protons and neutrons are present in the nucleus.
4. As Mercury has 120 nucleons, its mass number is 120.

Mercury (+2) ion contains 80 protons, 78 electrons, and 120 nucleons. Its mass number is 120.