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For batteries. | Atomic Number: | 82 | Atomic Symbol: | Pb | | Atomic Weight: | 207.2 | Electron Configuration: | 2-8-18-32-18-4 | | Shells: | 2,8,18,32,18,4 | Filling Orbital: | 6p2 | | Melting Point: | 254oC | Boiling Point: | 962oC | | Description: | Radioactive metal. |
History(Anglo-Saxon lead; L. plumbum) Long known, mentioned in Exodus.
the alchemists believed lead to be the oldest metal and associated with the
planet Saturn. Native lead occurs in nature, but it is rare. Lead is obtained
chiefly from galena (PbS) by a roasting process. Anglesite, cerussite, and minim
are other common lead minerals. Lead is a bluish-white metal of bright luster,
is very soft, highly malleable, ductile, and a poor conductor of electricity. It
is very resistant to corrosion; lead pipes bearing the insignia of Roman
emperors, used as drains from the baths, are still in service. It is used in
containers for corrosive liquids (such as sulfuric acid) and may be toughened by
the addition of a small percentage of antimony or other metals. Natural lead is
a mixture of four stable isotopes: 204Pb (1.48%), 206Pb (23.6%), 207Pb (22.6%),
and 208Pb (52.3%). Lead isotopes are the end products of each of the three
series of naturally occurring radioactive elements: 206Pb for the uranium
series, 207Pb for the actinium series, and 208Pb for the thorium series. Twenty
seven other isotopes of lead, all of which are radioactive, are recognized. Its
alloys include solder, type metal, and various antifriction metals. Great
quantities of lead, both as the metal and as the dioxide, are used in storage
batteries. Much metal also goes into calbe covering, plumbinb, ammunition, and
in the manufacture of lead tetraethyl. The metal is very effective as a sound
absorber, is used as a radiation shield around X-ray equipment and nuclear
reactors, and is used to absorb vibration. White lead, the basic carbonate,
sublimed white lead, chrome yellow, and other lead compounds are used
extensively in paints, although in recent years the use of lead in paints has
been drastically curtailed to eliminate or reduce health hazards. Lead oxide is
used in producing fine "crystal glass" and "flint glass" of a high index of
refraction for achromatic lenses. The nitrate and the acetate are souble salts.
Lead salts such as lead arsenate have been used as insecticides, but their use
in recent years has been practically eliminated in favor of less harmful organic
compounds. Care must be used in handling lead as it is a cumulative poison.
Environmental concerns with lead poisoning has resulted in a national program to
eliminate the lead in gasoline.
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