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 |
|
|
|
|
|
|
PLATINUM (Sp. platina, silver), Pt; at. wt. 195.09; at.
no.78; m.p. 17720C; b.p. 38271 1000C; sp. gr. 21.45 (200C);
valence 1?, 2, 3, or 4. Discovered in South America by Ulba
in 1735 and by Wood in 1741. The metal was used by pre-
Colombian Indians. Platinum occurs native, accompanied
by small quantifies of iridium, osmium, palladium, ruthen-
ium, and rhodium, all belonging to the same group of metals.
These are found in the alluvial deposits of the Ural moun-
tains, of Colombia, and of certain western American states.
Sperrylite (PtAs2) occurring with the nickel-bearing deposits
of Sudbury, Ontario, is the source of a considerable amount
of the metal. The large production of nickel offsets the fact
that there is only one part of the platinum metals in two
million parts of ore. Platinum is a beautiful silvery-white
metal, when pure, and is malleable and ductile. It has a
coefficient of expansion almost equal to that of soda4ime-
silica glass, and is therefore used to make sealed electrodes
in glass systems. The metal does not oxidize in air at any
temperature, but is corroded by halogens, cyanides, sulfur,
and caustic alkalis. It is insoluble in hydrochloric and nitric
acid, but dissolves when they are mixed as aqua regia, form-
ing chloroplatinic acid (H2PtCI~),.an important compound.
The metal is extensively used in jewelry, in wire and vessels
for laboratory use, and in many valuable instruments, in-
cluding thermocouple elements. It is also used for electrical
contacts, corrosion-resistant apparatus, and in dentistry.
Platinum~obalt alloys have magnetic properties. One such
alloy made of 76.7% Pt and 23.3% Co, by weight, is an
extremely powerful magnet that offers a B-H (max) almost
twice that of Alnivo V. Platinum resistance wires are used
for constructing high-temperature electric furnaces. The
metal is used for coating missile nose cones, jet engine fuel
nozzles, etc., which must perform reliably for long periods
of time at high temperatures. The metal, like palladium,
absorbs large volumes of hydrogen, retaining it at ordinary
temperatures but giving it up at red heat. In the finely divided
state platinum is an excellent catalyst, having long been used
in the contact process for producing sulfuric acid. It is also
used as a catalyst in cracking petroleum products. Fine
platinum wire will glow red hot when placed in the vapor~of
methyl alcohol. It acts here as a catalyst, converting the
alcohol to formaldehyde. This phenomenon has been used
commercially to produce cigarette lighters and hand warm-
ers. Hydrogen and oxygen explode in the presence of
platinum. The price of platinum has varied widely; more
than a century ago it was used to adulterate gold. It was
nearly eight times as valuable as gold in 1920; the present
price is about 31 40/troy ounce.
© 1999 F. Davies
Delphi O.E.M. Co.
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