INORGANIC CHEMISTRY A  B  C  D  E  F  G  H  I  J  K  L  M  N  O  P  Q  R  S  T  U  V  W  X  Y  Z                    HOME ABOUT CATEGORIES SITE MAP COPYRIGHT ADVERTISE CONTACT entire Web this site lead (Pb) Lead radiation shielding. Credit: L. Chang, wikipedia A soft, malleable, ductile, dense, metallic element that is bluish-white when freshly cut but tarnishes to gray when exposed to air. Lead occurs in period 6 of the periodic table and has the highest atomic number of any stable element. It is extracted chiefly from galena (lead sulfide, PbS). Anglesite (lead sulfate, PbSO4) and cerussite (lead carbonate, PbCO3) are two other lead-based minerals. Lead is used in lead-acid batteries, cable-sheathing, lead crystal, some solders, bullets, and radiation shielding (see picture). Like mercury, lead is a potent neurotoxin which can gradually accumulate in soft tissues and bone. For this reason, it is no longer used in making water pipes, paints, and antiknock compounds (to raise the octane level of gasoline). Lead has been known since ancient times. Its name is derived from the Anglo-Saxon laedan. The chemical symbol Pb comes from the Latin for "lead", plumbum, which is also the root for "plumbing". Lead was used in pipes, pewter, and paint by the Romans. atomic number 82 relative atomic mass 207.2 electron configuration 1s22s22p63s23p64s23d10 4p65s24d105p66s24f145d106p2 ionization energy 1st: 716 kJ/mol 2nd: 1,450 kJ/mol 3rd: 3,081 kJ/mol 4th: 4,083 kJ/mol oxidation states +2, +4 covalent radius 154 pm metallic radius 175 pm ionic radius 119 pm (Pb2+), 78 pm (Pb+4) relative density 11.35 (room temp) melting point 327.5 °C (621.5 °F) boiling point 1,749 °C (3,180 °F) Related category    • INORGANIC CHEMISTRY Also on this site: Encyclopedia of Alternative Energy & Sustainable Living Encyclopedia of History Transport Concepts & Designs (partner site) BACK TO TOP