Lead ( ) is a chemical element with the symbol Pb (from the Latin plumbum) and atomic number 82. It is a heavy metal, denser than most common materials. Lead is soft, malleable, and has a relatively low melting point. When freshly cut, it appears shiny gray with a bluish tint, but tarnishes to dull gray on exposure to air. Lead has the highest atomic number of any stable element, and three of its isotopes are endpoints of major nuclear decay chains of heavier elements.
Lead is a relatively unreactive post-transition metal. Its weak metallic character is shown by its amphoteric behavior: lead and lead oxides react with both acids and bases, and it tends to form covalent bonds. Lead compounds usually occur in the +2 oxidation state rather than the +4 state common in lighter members of the carbon group, with exceptions mostly limited to organolead compounds. Like the lighter members of the group, lead can bond with itself, forming chains and polyhedral structures.
Easily extracted from its ores, lead was known to prehistoric peoples in the Near East. Galena is its principal ore and often contains silver, encouraging its widespread extraction and use in ancient Rome. Production declined after the fall of Rome and did not reach similar levels until the Industrial Revolution. Lead played a role in developing the printing press, as movable type could be readily cast from lead alloys. In 2014, annual global production was about ten million tonnes, over half from recycling. Lead's high density, low melting point, ductility, and resistance to oxidation, together with its abundance and low cost, supported its extensive use in construction, plumbing, batteries, ammunition, weights, solders, pewter, fusible alloys, lead paints, leaded gasoline, and radiation shielding.
Lead is a neurotoxin that accumulates in soft tissues and bones. It damages the nervous system, interferes with biological enzymes, and can cause neurological disorders ranging from behavioral problems to brain damage. It also affects cardiovascular and renal systems. Lead's toxicity was noted by ancient Greek and Roman writers, but became widely recognized in Europe in the late 19th century.