Question

How is the nucleus of a uranium-238 atom different to the nucleus of a uranium-235 atom?

Answer 1

`""^238U` has 3 more neutrons than `""^235U`, and...........

Explanation:

These nuclides are both isotopes of uranium, and thus, each nucleus contains 92 protons - they would not be uranium isotopes otherwise.

The isotopes differ in the number of neutrons contained in their nucleus. `""^238U` contains `(238-92)` neutrons; `""^235U` contains `(235-92)` neutrons.

I forget which isotope is the fissile one. It's `""^235U` isn't it, and `""^238U` is the fertile isotope? Anyway, this is the chemistry not the physics section.