Protons neutrons and electrons

Question

How many protons neutrons and electrons does cs-138

Cs - 138

w + + +

Answer 1

138 is the total number of nucleons, that is protons and neutrons together. Cs is the 55th element in periodic table, that is, its nucleus charge is 55, so it has 55 protons. Hence it has 138-55=83 neutrons. Of course, it has 55 electrons, to balance the charge of its nucleus.