The atomic number of an element is based on the number of electrons around its core mass of its nucleus number of protons in its nucleus number of neutrons in its nucleus

Why are very high temperatures and pressures required for fusion to occur? to generate the neutrons that are needed to break the nuclei o to overcome the repulsion between the protons in the nuclei that join to maintain the proper conditions to keep the chain reaction going to keep the uranium fuel separate from the control rods