H' at. wt. (natural) 1.007967
at. wt. (H') 1.007822
at. no. 1
m.p. - 259.140C
b.p. - 252.870C
density 0.08988 gm./l
density (liquid) 70.8 gm/i. (-2530C)
density (solid) 7016 gm/i. (-2620C)
valence 1.
Electronic configuration
| K |
L |
M |
N |
O |
P |
Q |
| 1 |
2 |
3 |
4 |
5 |
6 |
7 |
| s |
s p |
s p d |
s p d f |
s p d f |
s p d f |
s p d f |
| 1 |
|
|
|
|
|
|
GOLD (Sanskrit Jual; anglo-Saxon gold), Au (L. aurum,
shining dawn); at. wt. 196.9665; at. no.79; m.p. 1064.430C;
b.p. 29400C; sp. gr. 19.32 (200C); valence 1 or 3. Known and
highly valued from earliest times. Gold is found in nature as
the free metal and in tellurides; it is very widely distributed
and is almost always associated with quartz or pyrite. It
occurs in veins and alluvial deposits, and is often separated
from rocks and other minerals by sluicing or panning opera-
tions. About two-thirds of the world's gold output now
comes from South Africa, and about two-thirds of the total
U.S. production comes from South Dakota and Nevada.
The metal is recovered from its ores by cyaniding, amalga-
mating, and smelting processes. Refining is also frequently
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done by electrolysis. Gold occurs in sea water to the
extent of 0.1 to 2 mg/ton, depending on the location where
the sample is taken. As yet no method has been found for
recovering gold from sea water profitably. It is estimated
that all the gold in the world, so far refined, could be placed
in a single cube fifty feet on a side. Of all the elements, gold
in its pure state is undoubtedly the most beautiful. It is
metallic, having a yellow color when in a mass, but when
finely divided it may be black, ruby, or purple. The Purple
of Cassius is a delicate test for auric gold. It is the most
malleable and ductile metal; one 9unce of gold can be
beaten out to 300 sq. ft. It is a soft metal and is usually
alloyed to give it more strength. It is a good conductor of
heat and electricity, and is unaffected by air and most
reagents. It is used in coinage and is a standard for monetary
systems in many countries. It is also extensively used for
jewelry, decoration, dental work, and for plating. It is used
for coating certain space satellites, as it is a good reflector
of infrared, and is inert. Gold, like other precious metals,
is measured in troy weight; when alloyed with other metals,
the term carat is used to express the amount ofgold present-
24 carats being pure gold. For many years the value of gold
was set by the United States at $20.67/troy oz; since 1934
this value has ,been fixed by law and Presidential Order at
$35.00/troy ounce, 9/10th fine. On March 17, 1968, because
of a gold crisis, a two-tiered pricing system was established
whereby gold would still continue to be used to settle
international accounts at the old $35.00/troy ounce price
while the price of gold on the private market would be
allowed to fluctuate. Since this time, the price of gold on the
free market has fluctuated between $37 and $44/troy ounce.
On March 19, ~~l968, President Johnson signed into law a
bill removing the last statutory requireme,nt for a gold
backing against U.S. currency. The cominonest gold com-
pounds are auric chloride (AuCl3) and chlorauric acid
(HAuCI4), the latter being used in photography for toning
the silver image. Gold has twenty-one isotopes; Au198,
with a half-life of 2.7 days is used for treating cancer and
other diseases. Disodium aurothiomalate is administered
intramuscularly as a treatment for arthritis. A mixture of
one part nitric acid with three of hydrochloric acid is called
aqua regia, because it dissolved Gold, the King of Metals.
Gold is available commercially with a purity of 99.999+ %.
For many years the temperature assigned to the freezing
point of gold has been 1063.00C. This has served as a calibra-
tion point for the International Temperature Scales (ITS-27
and ITS-48) and the International Practical Temperature
Scale (ITPS-48). In 1968 a new International Practical
Temperature Scale (ITPS-68) was adopted, which demands
that the freezing point of gold be changed to 1064.430C.
Although workers in precision temperature measurement
should adopt IPTS-68 immediately, many of the scale
changes are of minor significance to the routine user.
IPTS-68 has defined several other fixed temperature points,
among which are the boiling points of hydrogen, neon,
oxygen, and sulfur, and the freezing points of zinc, silver,
tin, lead, antimony, and aluminum. These new fixed point
values have been adopted in this description of the elements.
© 1999 F. Davies
Delphi O.E.M. Co.
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