Lead is a chemical element with symbol Pb and atomic number 82. A heavy metal with a density exceeding that of most common materials, it is malleable and has a low melting point for a metal. Chemically, it is a relatively unreactive post-transition metal. Lead was known to prehistoric people. A principal ore of lead, galena, often bears silver; interest in silver sparked lead extraction and use in ancient Rome. Lead production declined after the fall of Rome and did not reach comparable levels until the Industrial Revolution. Nowadays, global production of lead is about ten million tonnes annually. Its high density, low melting point, high malleability, relative inertness to oxidation, relative abundance, and low cost have resulted in its extensive use in construction, plumbing, batteries, bullets and shot, weights, solders, pewters, fusible alloys, and radiation shielding. In the late 19th century, lead was recognized as highly toxic, and since then it has been phased out for many uses. A neurotoxin that accumulates in soft tissues and bones, it can damage the nervous system and cause brain and blood disorders. (Full article...)
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