Richards, Theodore William (1868-1928)

US chemist who was awarded the Nobel Prize for Chemistry in 1914 for determining as accurately as possible the relative atomic masses of a large number of elements. He also investigated the physical properties of the elements, such as atomic volumes and the compressibilities of non-metallic solid elements.

Richards was born in Germantown, Pennsylvania, and studied at Harvard, where he was professor from 1901.

Introducing various new analytical techniques, Richards made accurate atomic weight measurements for 25 elements; his co-workers determined 40 more. In 1913, he detected differences in the atomic weights of ordinary lead and samples extracted from uranium minerals (which had arisen by radioactive decay) - one of the first convincing demonstrations of the uranium decay series and confirming English chemist Frederick Soddy's prediction of the existence of isotopes.