A Se ion has a mass number of 79 and a charge of - 2. Determine the number of neutrons, protons, and electrons in this ion.

45, 34, 36

Explanation:

The atomic number of Selenium is 34 and the atomic number is 79 also the atom has gained two electron denoted by superscript - 2

number of neutrons = mass number - atomic number = 79 - 34 = 45

number of proton = atomic number = 34

number of electron = 34 + 2 = 36. In an atom the number of proton is always equal to number of electron if the atom is neutral but this Se atom has gain two so the number of electron will exceed the number of proton by 2.