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lead (Pb)



lead shielding
Lead radiation shielding.
Credit: L. Chang, Wikipedia

various uses of lead and its alloys
Some traditional uses of lead and its alloys

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 group IVA and 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) by converting the ore to the oxide by roasting, then smelting with coke. Anglesite (lead sulfate, PbSO4) and cerussite (lead carbonate, PbCO3) are two other lead-based minerals.

Lead dissolves in dilute nitric acid, but is otherwise resistant to corrosion, because of a protective surface layer of the oxide, sulfate, etc.

Lead is used in lead-acid batteries, cable-sheathing, lead crystal, some solders, bullets, and radiation shielding. 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)


Compounds of lead

Lead forms two series of salts: the lead (II) compounds are more stable than the lead (IV) compounds. Lead (II) oxide (PbO), or litharge, is a yellow crystalline solid made by oxidizing lead; it is used in lead-acid storage batteries, glass, and glazes, and has a melting point of 880°C. Lead (IV) oxide (PbO2) is a brown crystalline solid and a powerful oxidizing agent used in matches, fireworks, and dyes; it decomposes at 290°C. Trilead tetroxide (Pb3O4), or red lead, is an orange-red powder made by oxidizing litharge; it is used in paints, inks, glazes, and magnets. Lead tetraethyl (Pb[C2H5]4) is a colorless liquid made by reacting lead/sodium alloy with ethyl chloride.


Lead poisoning

Lead and several of its compounds are poisonous. Lead poisoning (plumbism) may be acute or chronic. Acute lead poisoning, which may follow inhalation of lead fumes or dust, causes abdominal pain, vomiting, and diarrhea, with paralysis, convulsions, and sometimes encephalitis. In chronic poisoning a characteristic bluish marking of gums ("lead line") is seen and the peripheral nerves are affected; there is also anemia. Treatment is with edetate. The use of lead in paints is now strictly controlled. See also separate article on lead poisoning.


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