Palladium is a Block D, Group 10, Period 5 element. The number of electrons in each of Palladium's shells is 2, 8, 18, 18 and its electronic configuration is [Kr] 4d¹⁰. In its elemental form palladium's CAS number is 7440-05-3. The palladium atom has a radius of 137.6.pm and it's Van der Waals radius is 163.pm. Palladium is a member of the palladium group of metals. It is an excellent hydrogenation and dehydrogenation catalyst and available in many Organo-metallic forms for this purpose. It is alloyed with gold, silver, iridium and other palladium group elements and used in jewelry. The metal is used in dentistry, watch making, and in making surgical instruments and electrical contacts. Palladium is available as metal and compounds with purities from 99% to 99.999% (ACS grade to ultra-high purity); metals in the form of foil, sputtering target, and rod, and compounds as submicron and nanopowder. Palladium was first discovered by William Hyde Wollaston in 1803. See Palladium research below. Palladium was first discovered by William Hyde Wollaston in 1803. See Palladium research below.