Hello!
the atomic difference between uranium-235 and uranium-238 is that <span>uranium-235 has three fewer neutrons than uranium-238
Isotopes are atoms of the same elements which are only different in their amount of neutrons. That difference in the number of neutrons gives them different masses. Some isotopes are unstable, and they release neutrons (radiation) to transform into other, more stable, isotopes. When this happens the isotope is called a "radioactive isotope".
Have a nice day!</span>
