Question

How do you calculate the atomic number of an isotope?

Answer 1

Atomic number `Z`, is a given. The atomic numbers of isotopes are the same.

Explanation:

The number of protons, positively charged nuclear particles, determines the the identity of the element: `Z=1, H`; `Z=2, He`; `Z=3, Li`; etc.

On the other hand, a given element can have different numbers of neutrons, neutrally charged nuclear particles, and this difference gives rise to the existence of isotopes.

For hydrogen, for instance, `""^1H`, the protium isotope (1 proton only in the nucleus), `""^2H`, the deuterium isotope (a proton and a neutron in the nucleus) `""^3H`, (a proton and 2 neutrons) the tritium isotope. These are all hydrogen atoms because they have the 1 proton in their nucleus, and are more or less the same chemically. Most elements have one or more isotopes. As `Z` increases the range of isotopes becomes greater.