How many protons, neutrons and electrons are in uranium 235 and uranium 238?
Uranium is atomic number 92 – this means it has 92 protons – which in a neutral atom means it also has 92 electrons. 235 and 238 are the mass numbers (or nucleon number) of two of its isotopes. The neutron number = the mass number – the atomic(proton) number. So just subtract 92 from both 235 and 238 to get your answer.