A Se ion has a mass number of 76 and a charge of - 2. Determine the number of neutrons, protons, and electrons in this ion.

Neutron = 42

Proton = 34

Electron = 36

Explanation:

The atomic number (also known as the proton number) of an element does not change even if the element gain or loss electrons.

With this understanding,

Se has atomic number (proton number) = 34

From question,

Mass number of Se ion = 76

Charge = - 2

Neutron number = Mass number - proton number

Neutron number = 76 - 34 = 42

Since Se ion has a charge of 2-, it means it has gain electrons

Therefore the electron number = 34 + 2 = 36