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
Power residue symbol Hilbert symbol formula_24 for the prime formula_4 by in the case formula_4 coprime to "n", where formula_28 is any uniformising element for the local field formula_29. The formula_14-th power symbol may be extended to take non-prime ideals or non-zero elements as its "denominator", in the same way that the Jacobi symbol extends the Legendre symbol. Any ideal formula_31 is the product of prime ideals, and in one way only: The formula_14-th power symbol is extended multiplicatively: For formula_35 then we define where formula_37 is the principal ideal generated by formula_38 Analogous to the quadratic Jacobi symbol, this symbol is multiplicative