Identifying Isotopes through Representations

By John T. Moore

Part of Chemistry For Dummies Cheat Sheet

In Chem I, you may have to identify isotopes, which are atoms of the same element that have different numbers of neutrons. The following representation allows you to identify a specific isotope of an element. It is used extensively in balancing nuclear reactions.


X = element symbol

Z = atomic number (number of protons)

A = mass number (number of protons + number of neutrons)