To determine the atomic mass number of an element, you need to add the number of protons and neutrons in the nucleus of an atom. The number of protons is equal to the atomic number of the element.
In the case of Zn (zinc), the atomic number is 30, which means it has 30 protons in its nucleus.
To find the number of neutrons, subtract the atomic number from the total number of neutrons in the ion. In this case, the Zn+2 ion has 35 neutrons.
Therefore, the atomic mass number of Zn is calculated as follows:
Atomic mass number = number of protons + number of neutrons Atomic mass number = 30 (protons) + 35 (neutrons) Atomic mass number = 65
So the atomic mass number of Zn is 65.