Platinum

iridium ← platinum → gold

Pd
↑
Pt
↓
Ds

Periodic Table - Extended Periodic Table

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·cm⁻³

Liquid density at m.p.

19.77 g·cm⁻³

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⁻¹

Heat of vaporization

469 kJ·mol⁻¹

Heat capacity

(25 °C) 25.86 J·mol⁻¹·K⁻¹

Vapor pressure
P/Pa	1	10	100	1 k	10 k	100 k
at T/K	2330	(2550)	2815	3143	3556	4094

Atomic properties

Crystal structure

cubic face centered

Oxidation states

1, 2, 3, 4
(mildly basic oxide)

Electronegativity

2.28 (Pauling scale)

Ionization energies

1st: 870 kJ/mol

2nd: 1791 kJ/mol

Atomic radius

135 pm

Atomic radius (calc.)

177 pm

Covalent radius

128 pm

Van der Waals radius

175 pm

Miscellaneous

Magnetic ordering

paramagnetic

Electrical resistivity

(20 °C) 105 nΩ·m

Thermal conductivity

(300 K) 71.6 W·m⁻¹·K⁻¹

Thermal expansion

(25 °C) 8.8 µm·m⁻¹·K⁻¹

Speed of sound (thin rod)

(r.t.) 2800 m·s⁻¹

Young's modulus

168 GPa

Shear modulus

61 GPa

Bulk modulus

230 GPa

Poisson ratio

0.38

Mohs hardness

4 - 4.5

Vickers hardness

549 MPa

Brinell hardness

392 MPa

CAS registry number

7440-06-4

Selected isotopes

Main article: Isotopes of platinum
iso	NA	half-life	DM	DE (MeV)	DP
¹⁹⁰Pt	0.01%	6.5×10¹¹ y	α	3.18	¹⁸⁶Os
¹⁹¹Pt	syn	2.96 d	ε	?	¹⁹¹Ir
¹⁹²Pt	0.79%	Pt is stable with 114 neutrons
¹⁹³Pt	syn	50 y	ε	?	¹⁹³Ir
^193mPt	syn	4.33 d	IT	0.1355e	¹⁹³Pt
¹⁹⁴Pt	32.9%	Pt is stable with 116 neutrons
¹⁹⁵Pt	33.8%	Pt is stable with 117 neutrons
^195mPt	syn	4.02 d	IT	0.1297e	¹⁹⁵Pt
¹⁹⁶Pt	25.3%	Pt is stable with 118 neutrons
¹⁹⁷Pt	syn	19.8913 h	β^-	0.719	¹⁹⁷Au
^197mPt	syn	1.59 h	IT	0.3465	¹⁹⁷Pt
¹⁹⁸Pt	7.2%	Pt is stable with 120 neutrons

References

This page is about platinum the chemical element. For other uses, see Platinum (disambiguation).

Platinum (IPA: /ˈplætɪnəm/) is a chemical element in the periodic table that has the symbol Pt and atomic number 78. A heavy, malleable, ductile, precious, grey-white transition metal, platinum is resistant to corrosion and occurs in some nickel and copper ores along with some native deposits. Platinum is used in jewelry, laboratory equipment, electrical contacts, dentistry, and automobile emissions control devices.

1 Notable characteristics
2 Applications
3 History
4 Occurrence
5 Precautions
6 Rarity and color
7 World production
8 References
9 See also
10 External links

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Notable characteristics

An assortment of native platinum nuggets

When pure, the metal appears greyish-white and firm. The metal is corrosion-resistant. The catalytic properties of the six platinum family metals are outstanding. 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 slightly less than twice the price of gold^[1]. In the 18th century, platinum's rarity made King Louis XV of France declare it the only metal fit for a king^[2].

Platinum possesses high resistance to chemical attack, excellent high-temperature characteristics, and stable electrical properties. All these properties have been exploited for industrial applications. Platinum does not oxidize 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, and +4. The +1 and +3 oxidation states are less common, and are often stabilized by metal metal bonding in bimetallic (or polymetallic) species.

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Applications

As a catalyst in the catalytic converter, an optional component of the gasoline-fueled automobile exhaust system (see "Notable characteristics" in this article).
As a catalyst in fuel cells. Reducing the amount of platinum required (and thus cost) is a major focus of fuel cell research.
Certain platinum-containing compounds are capable of crosslinking (or alkylating) with DNA and are chemotherapeutic agents owing to this capability. For example, cisplatin, Carboplatin and oxaliplatin belong to this class of drugs.
Platinum resistance thermometers.
Electrodes for use in electrolysis.
In the Clark polarographic electrode for measuring oxygen tension.
A wide range of jewellery
As a catalyst in the curing of silicone elastomers.
As a catalyst in glow plugs in some model engines.

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History

Naturally-occurring platinum and platinum-rich alloys have been known for a long time. Though the metal was used by pre-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 word platinum comes from the Spanish word platina, meaning "little silver."

Platinum was discussed by astronomer Antonio de Ulloa and Don Jorge Juan y Santacilia (1713–1773), both appointed by King Philip 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 Granada (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 Royal 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 alchemical symbol for platinum (shown left) was made by joining the symbols of silver and gold.

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Occurrence

Platinum ore

Platinum is an extremely rare metal, occurring as only 5 ppb in the Earth's crust.

Platinum is often found chemically uncombined as native platinum and alloyed with iridium as platiniridium. The platinum arsenide, sperrylite (PtAs₂), is a major source of platinum associated with nickel ores in the Sudbury Basin deposit in Ontario, Canada. The rare sulfide mineral cooperite, (Pt,Pd,Ni)S, contains platinum along with palladium and nickel. Cooperite occurs in the Merensky Reef within the Bushveld complex, Transvaal, South Africa. South Africa is the largest producer of platinum in the world.

Platinum, often accompanied by small amounts of other platinum family metals, occurs in alluvial 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 nickel 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.

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Precautions

According to the Centers for Disease Control and Prevention, short-term exposure to "platinum salts may cause irritation of the eyes, nose, and throat" and long-term exposure "may cause both respiratory and skin allergies." The current OSHA standard is 0.002 milligram per cubic meter of air averaged over an 8-hour work shift. ^[3]

Certain platinum complexes (cis-platin) have been used in chemotherapy, as they have very good anti-tumor activity, particularly when used to combat testicular cancer,^{[citation needed]} although they also cause cumulative, irreversible kidney damage,^{[citation needed]} as well as deafness.^{[citation needed]}

As platinum is a catalyst in the manufacture of the silicone rubber and gel components of several types of medical implants (breast implants, joint replacement prosthetics, artificial lumbar discs, vascular access ports),^{[citation needed]} the possibility that platinum free radicals could enter the body and cause adverse effects has merited study. However, the FDA has reviewed the issue as related to breast implants, and did not agree with a recent study that showed possible in vivo toxicity.^[4]

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Rarity and color

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 second highest possible, ranking above gold, silver and bronze, but below "Diamond". 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 is not as common as 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.

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World production

World supply of platinum is around 7 million troy ounces (199,000 kg) per year. ^[5]^[6] Platinum's cost fluctuates around USD $1100 per ounce ($35/g). [2]

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