Chemistry J.J. Thomson of Cambridge University discovered the electron and soon after the French scientist Becquerel as well as the couple Pierre and Marie Curie investigated the phenomenon of radioactivity. In a series of pioneering scattering experiments Ernest Rutherford at the University of Manchester discovered the internal structure of the atom and the existence of the proton, classified and explained the different types of radioactivity and successfully transmuted the first element by bombarding nitrogen with alpha particles. His work on atomic structure was improved on by his students, the Danish physicist Niels Bohr and Henry Moseley. The electronic theory of chemical
British nuclear tests at Maralinga nuclear warheads containing plutonium-239. In total, "Vixen B" scattered 22.2 kg of plutonium around the Maralinga test site known as Taranaki, in particles of widely divergent size. Plutonium is not particularly dangerous externally - it emits alpha particles which are stopped by of air, or the dead layer of skin cells on the body, and is not a very intensive source of radiation, due to its long half-life of 24,000 years. It is most dangerous when it enters the body, in the worst case by breathing, and therefore tiny particles, often the result of such explosion testing, are the worst