Period 6 element heavy metal, lead is a neurotoxin that accumulates both in soft tissues and the bones. Lead poisoning has been documented from ancient Rome, ancient Greece, and ancient China. Bismuth is a chemical element with symbol Bi and atomic number 83. Bismuth, a trivalent other metal, chemically resembles arsenic and antimony. Elemental bismuth may occur naturally uncombined, although its sulfide and oxide form important commercial ores. The free element is 86% as dense as lead. It is a brittle metal with a silvery white color when newly made, but often seen in air with a pink tinge owing to the surface
Period 6 element price of approximately US$4,575 per kilogram (US$142.30 per troy ounce) as of August 2011; it is also of critical strategic military importance, for its use in high performance military jet and rocket engines. Osmium is a chemical element with the symbol Os and atomic number 76. It is a hard, brittle, blue-gray or blue-black transition metal in the platinum family and is the densest naturally occurring element, with a density of (slightly greater than that of iridium and twice that of lead). It is found in nature as an alloy, mostly in platinum ores; its alloys with platinum, iridium, and