Uranium-235 was discovered by nobody.
Uranium-235 -LRB- 235U -RRB- is an isotope of uranium making up about 0.72 % of natural uranium .. isotope of. Isotopes of uranium. uranium. uranium. natural uranium. natural uranium. Unlike the predominant isotope uranium-238 , it is fissile , i.e. , it can sustain a fission chain reaction .. uranium. uranium. uranium-238. uranium-238. fissile. fissile. fission. nuclear fission. chain reaction. chain reaction. It is the only fissile isotope that is a primordial nuclide or found in significant quantity in nature .. fissile. fissile. primordial nuclide. primordial nuclide. Uranium-235 has a half-life of 703.8 million years .. half-life. half-life. It was discovered in 1935 by Arthur Jeffrey Dempster .. Arthur Jeffrey Dempster. Arthur Jeffrey Dempster. Its -LRB- fission -RRB- nuclear cross section for slow thermal neutrons is about 584.994 barns .. fission. nuclear fission. nuclear cross section. nuclear cross section. For fast neutrons it is on the order of 1 barn .. barn. Barn ( unit ). Most but not all neutron absorptions result in fission ; a minority result in neutron capture forming uranium-236 .. uranium. uranium. fission. nuclear fission. neutron capture. neutron capture. uranium-236. uranium-236