Synopsis from the
CRC Handbook of Chemistry and Physics
92nd Edition 2011-2013
|Lead — (Anglo-Saxon lead), Pb (L. plumbum); at. wt. 207.2(1); at.
no. 82; m.p. 327.46 °C; b.p. 1749 °C; sp. gr. 11.35 (20 °C); valence
2 or 4. Long known, mentioned in Exodus. The alchemists believed
lead to be the oldest metal and associated it 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 (PbSO4), cerussite (PbCO3), and minim (Pb3O4) 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
(1.4%), 206Pb (24.1%), 207Pb (22.1%), and 208Pb (52.4%). 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. Forty-three 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.
Lead is also used for cable covering, plumbing, and ammunition.
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. Lead, alloyed with tin, is
used in making organ pipes. White lead, the basic carbonate,
sublimed white lead (PbSO4), chrome yellow (PbCrO4), red
lead (Pb3O4), 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 soluble 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 concern with
lead poisoning led to elimination of lead tetraethyl in gasoline.
The U.S. Occupational Safety and Health Administration
(OSHA) has recommended that industries limit airborne lead
to 50 μg/cu. meter. Lead is priced at about 90¢/kg (99.9%).