the fission of 235u (uranium - 235) nuclei is initiated by
Uranium-235 The fission of one atom of uranium-235 generates 202.5 MeV = 3.24 × 10−11 J, which translates to 19.54 TJ/mol, or 83.14 TJ/kg.[2] This is around 2.5 million times more than the energy released from burning coal.[3] When 235 92U nuclides are bombarded with neutrons, one of the many fission reactions that it can undergo is the following (shown visually in the adjacent image):
Alpha particle The best-known source of alpha particles is alpha decay of heavier (> 106 u atomic weight) atoms. When an atom emits an alpha particle in alpha decay, the atom's mass number decreases by four due to the loss of the four nucleons in the alpha particle. The atomic number of the atom goes down by exactly two, as a result of the loss of two protons – the atom becomes a new element. Examples of this sort of nuclear transmutation are when uranium becomes thorium, or radium becomes radon gas, due to alpha decay.