Introduction Uranium-235 is less stable than uranium-238, but only slightly so. Both isotopes are highly unstable. U-235 has 92 protons and 143 neutrons in its nucleus, meaning it has a 1.55 neutron to proton ratio (N/P). In comparison, most stable elements have N/P ratios somewhere between 0.7 and 1.1. Uranium-238 has 146 neutrons in its […]