| |
Platinum
Item
# p6921
|
Platinum
is a chemical element theperiodic table that has the symbol
Pt and atomic number 78. A heavy, malleable,
ductile, precious, grey-whitetransition metal, platinum
is resistant to corrosion and occurs in some nickel and
copper ores along with some native deposits. Platinum
is used in jewellery, laboratory equipment, electrical
contacts, dentistry, and automobile emissions control
devices.
Contents
1 Notable characteristics
2 Applications
3 History
4 Occurrence
5 Precautions
6 Rarity and Color
|
Notable
characteristics
p6897
The metal appears silvery-white
when pure, and firm. The metal is corrosion-resistant.
The catalytic properties of the six platinum family
metals are outstanding (a mixture of hydrogen andoxygen
explodes in the presence of platinum). For this catalytic
property, platinum is used in catalytic converters,
incorporated in automobile exhaust systems, as well
as tips of spark plugs.
Platinum's wear- and tarnish-resistance characteristics
are well suited for making fine jewelry.
Platinum is more precious
than gold. The
price of platinum changes along with its availability,
but it normally costs about twice as much as gold. In
the 18 th century, platinum's rarity made King Louis
XV of France declare it the only metal fit for a king.
Platinum possesses remarkable resistance to chemical
attack, excellent high-temperature characteristics,
and stable electrical properties. All these properties
have been exploited for industrial applications. Platinum
does not oxidise in air at any temperature, but can
be corroded by cyanides,halogens,sulfur, and caustic
alkalis. This metal is insoluble in hydrochloric and
nitric acid, but does dissolve in the mixture known
as aqua regia (forming chloroplatinic acid). Common
oxidation states of platinum include +2, +3, and +4. |
 |
General |
| Name, Symbol, Number |
platinum, Pt, 78 |
| Chemical series |
transition metals |
| Group, Period, Block |
10, 6, d |
| Appearance |
grayish white |
| Atomic mass |
195.084(9) g/mol |
| Electron configuration |
[Xe] 4f14 5d9 6s1 |
| Electrons per shell |
2, 8, 18, 32, 17, 1 |
Physical
properties |
| Phase |
solid |
| Density (near r.t.) |
21.45 g/cm³ |
| Liquid density at m.p. |
19.77 g/cm³ |
| Melting point |
2041.4 K
(1768.3 °C, 3214.9 °F) |
| Boiling point |
4098 K
(3825 °C, 6917 °F)
|
| Heat of fusion |
22.17 kJ/mol |
| Heat of vaporization |
469 kJ/mol |
| Heat capacity |
(25 °C) 25.86 J/(mol•K) |
P/Pa |
1 |
10 |
100 |
1
k |
10
k |
100
k |
|
|
Applications
Item # p7141 |
•
catalyst utilized in the catalytic converter, an optional
component of the gasoline-fuelled automobile exhaust system
(see "Notable characteristics" in this article),
• certain platinum-containing compounds are capable
of intercalating into DNA and are chemotherapeutic agents
owing to this capability. For example,cisplatin, carboplatin
and oxaliplatin belong to this class of drugs,
• platinum resistance thermometers,
• elektrodes for use in elektrolysis. |
History |
| Discovered by: |
Antonio de Ulloa |
| Discovered at: |
South America |
| Discovered when: |
1735 |
| Origin of name: |
From the Spanish word "platina"
meaning "silver" |
Item # pma6753
|
Naturally-occurring
platinum
and platinum-rich alloys have been known for a long
time. Though the metal was used bypre-Columbian Native
Americans, the first European reference to platinum
appears in 1557 in the writings of the Italian humanist
Julius Caesar Scaliger (1484-1558) as a description
of a mysterious metal found in Central American mines
between Darién (Panama) and Mexico ("up
until now impossible to melt by any of the Spanish arts").
The Spaniards named the metal "platina," or
little silver, when they first encountered it in Colombia.
They regarded platinum as an unwanted impurity in the
silver they
were mining, and often discarded it.
Platinum was discovered by astronomer Antonio de Ulloa
and Don Jorge Juan y Santacilia (1713-1773), both appointed
by King Phillip V to join a geographical expedition
in Peru that lasted from 1735 to 1745. Among other things,
Ulloa observed the platina del pinto, the unworkable
metal found with gold in New Grenada (Colombia). British
privateers intercepted Ulloa's ship on the return voyage.
Though he was well-treated in England, and even made
a member of the Rojal Society he was prevented from
publishing a reference to the unknown metal until 1748.
Before that could happen Charles Wood independently
isolated the element in 1741.
The alcemical symbol for platinum (shown below) was
made by joining the symbols of silver
and gold.
The definition of a metre for a
long time was based on the distance between two marks
on a bar of a platinum-iridium alloy housed at the Bereau
Interenational des Poids et Mesures, France. A platinum-iridium
cylinder serves to this day as the standard of the kilogram
and is housed in the same facility as the metre bar.
Platinum is also used in the definition of the Standart
hydrogen electrode.
|
Occurrence
Item # p6800 |
Platinum
is often found as native platinum and alloyed with iridium
as platiniridium. The platinum arsenide,sperrylite, is
a major source of platinum associated with nickel ores
in the Sudbury Basin deposit. The rare sulfide mineral
cooperative, (Pt,Pd,Ni)S, contains platinum along with
palladium and nickel. Cooperite occurs in the Menersky
Reef within the Bushveld complex, Transvaal,South Africa.
Platinum, often accompanied by small amounts of other
platinum family metals, occurs inalluvial placer deposits
in the Witwatersrand of South Africa, Colombia, Ontario,
the Ural Mountains, and in certain western American states.
Platinum is produced commercially as a by-product of nicel
ore processing in the Sudbury deposit. The huge quantities
of nickel ore processed makes up for the fact that platinum
is present as only 0.5 ppm in the ore.
|
Precautions
Item # 6918
|
| This
metal doesn't normally cause health problems due to its
unreactive nature. Platinum compounds rarely occur in
nature. Certain platinum complexes (cis-platin) have been
used in chemotherapy, as they have very good anti-tumor
activity, though they do unfortunately cause cumulative
irreversible kidney damage. |
Rarity
and Color
Item # men007 |
| Platinum's
rarity as a metal has caused advertisers to associate
it with exclusivity and wealth. "Platinum" credit
cards have greater privileges than do "gold"
ones. "Platinum awards" are the highest possible,
ranking above gold, silver and bronze. For example, a
musical album that has sold more than 1,000,000 copies,
will be credited as "platinum". And some products,
such as blenders and vehicles, with a silvery-white colour
are identified as "platinum". Platinum is considered
a precious
metal, although its use as such is much more rare
than the use of gold
or silver. The
frame of the Crown of Queen Elizabeth the Queen Mother,
manufactured for her Coronation as Consort of King George
VI is made of platinum. It was the first British Crown
to be made of that metal. Due to its rarity, platinum
is a highly priced metal, more so than gold
or silver. |
Item # NE 6105
|
Platinum
jewelry is the perfect choice for a lifetime
of everyday wear. Its density and weight make it more
durable than other jewelry metals. Platinum does not
wear away and holds precious stones firmly and securely.
Like all precious metals, platinum scratches. However,
the scratch on a platinum piece is merely a displacement
of the metal and none of its volume is lost. So, even
though wearing it each and every day may leave an impression
on the surface, it remains what it was - a symbol for
all things eternal.
Platinum
is a diamond's best friend—complimenting beautifully
these qualities.
Your best friend we are- Cubic
Zirconia CZ Platinum Jewelry Team.
Platinum Care
Cleaning platinum jewelry with mild, soapy warm water
should be sufficient to maintain the metal's shine and
polish. As with other fine jewelry, it should be stored
in a fabric-lined box. Do not wear platinum while doing
rough work, and avoid contact with harsh chemicals.
If platinum becomes scratched or a patina begins to
develop, a jeweler can restore the original shine .
View our beautiful Chic
Platinum jewelry collection.
|
|
|
