why doe the splitting of uranium 235 nuclei release energy but the joining of hydrogen atom also release energ

Answer 1

There is a small amount of mass that is converted to energy according to Einstein's E = mc^2. This occurs in both situations. If we were to measure the mass of the materials before the fission or fusion we would notice that the mass of the materials afterward was slightly smaller.

Answer 2

An easy concept to consider is that all atoms are held together with 'nuclear glue.' When a heavy atom is split into two fragments (new atoms), less 'glue' is required to hold them together and the excess glue (represented by a 'mass discrepancy') is converted to energy per Einstein's equation E=mC2. Of course the split uranium 235 nucleus produces fragments and neutrons and the 'before' and 'after' total masses must be calculated to identify the mass discrepancy. Only the very heavy or very light elements can yeld a significant mass discrepancy and therefore useful energy. When two atoms (hydrogen) are fused together, the 'after' glue is less than the 'before' glue and there is also a mass discrepancy that is converted to energy. A very different mechanism holds for the creation of new molecules where the combination of atoms (affecting only the electrons) produces excess energy (exothermic) or an energy deficit (endothermic) either heating or cooling the constituents but not changing their total mass.

Answer 3

yes,so