Where are metalloids used in everyday life?

Boron : It is used in many cleaning products- detergents and bleaches.
Silicon : Silicon parts are used in computers, transistors, solar cells, LCD screens and other semiconductor devices.
Germanium : Create alloys in florescent lamps,Solar Cells,LEDs and other light emitting devices
Arsenic : car batteries,added to animal food to prevent disease and to promote growth
Antimony : used in machine bearings,used in way in the production of diodes, Hall effect devices and infra-red detectors,
Tellurium : used in making ceramics, chalcogenide glasses, tinting glasses,
Polonium : Polonium is used to eliminate static electricity produced during processes such as rolling paper, wire and sheet metal.
Astatine : used as a radioactive tracer and in cancer treatment.

Outermost (valence) electrons