Week 8:  Semiconductor-- GERMANIUM: Ge: atomic # 32, a shiny hard silver/white metalloid similar to tin. Same crystal structure as diamond. One of the few substances that expands as it freezes!  Was predicted by Mendeleev, but was proved to exist by Clemens Winkler in 1886.

It is a semiconductor material used in transistors. It was used in "solid state" electronics from the 1950's until the 1970's, then silicon became more commonly used.  Solid state components have no mechanical action , but electromagnetic action instead. I always wondered what that meant.