The nucleus of each atom contains protons and neutrons. While the number of protons defines the element (e.g., hydrogen, carbon, etc.) and the sum of the protons and neutrons gives the atomic mass, ...

The different types of chlorine are called isotopes of chlorine ... A = 64 Number of neutrons N = 64 - 30 = 34 Since this is a nucleus there are no electrons There are 30 protons and 34 neutrons.

The relative charge of a nucleus is the same as its proton (atomic) number. Key fact: isotopes are forms of an element that have the same number of protons but different numbers of neutrons.