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 University of California, Berkeley in 1940. Three years later, it was found in nature; however, with an estimated amount of less than 28 grams (1 oz) at given time, astatine is the least abundant element in Earth's crust among non-transuranium elements. Among astatine isotopes, six (with mass numbers 214 to 219) are present in nature as the result of decay of heavier elements; however, the most stable astatine-210 and the industrially used astatine-211 are not. Radon is a chemical element with symbol Rn and atomic number 86. It is a radioactive, colorless, odorless, tasteless noble gas, occurring naturally as the