How many neutrons are in ""^239 Pu?

1 Answer
Jun 4, 2016

There are 145 neutrons in the ""^239Pu nucleus.

Explanation:

You specified elemental plutonium. Thus we know for a fact that Z = 94. Since we have the mass number specified by the isotope notation, there are 239-94 massive, neutral particles in the plutonium nucleus.

To what does Z refer?