Strontium is a Block S, Group 2, Period 5 element. The electronic configuration is [Kr] 5s2. In its elemental form strontium's CAS number is 7440-24-6. The strontium atom has a radius of 215.1.pm and it's Van der Waals radius is 200.pm. Strontium has low tech applications as an additive to flares and pyrotechnics because of the bright crimson flame produced by its salts. Strontium 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. It also has many high technology applications because of its high refractive index as a titanate in glass, as a "getter" in electron tubes and as a dopant for numerous perovskite formulations to produce cathodes for oxygen generation or solid oxide fuel cells.