ABSTRACT

One sometimes hears people say that the nineteenth century was the really exciting age of chemistry. It was indeed a period of great advances, with two in particular standing out from the rest: the atomic theory, and the 'periodic table'. Physicists finally proved to everyone's satisfaction that atoms really exist; showed that each chemical element has atoms with a specific number of protons, neutrons and electrons; and showed that the electrons occupy discrete 'orbitals' around an atom's nucleus. Nitrogen is one of the most plentiful of all chemical elements, making up about four-fifths of the air we breathe. Hermann Staudinger found that the size of a polymer molecule could vary enormously, but it could typically be made of thousands or even tens of thousands of small molecules linked together. Most of the new chemical elements were 'trans-uranium' elements, highly radioactive and unstable, which were made in minute quantities in nuclear reactions.