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Platinum
*** Shopping-Tip: Platinum
{{otheruses}}
{{Elementbox_header | number=78 | symbol=Pt | name=platinum | left=
iridium .html">gold
_above=palladium|Pd | below=
darmstadtium Ds | color1=#ffc0c0 | color2=black }}
{{Elementbox_series |
transition metals }}
{{Elementbox_groupperiodblock | group=10 | period=6 | block=d }}
{{Elementbox_appearance_img | Pt,78| grayish white }}
{{Elementbox_atomicmass_gpm |
1 E-25 kg 195.084List of elements by atomic mass (9) }}
{{Elementbox_econfig | [
xenon Xe] 4f
14 5d
9 6s
1 }}
{{Elementbox_epershell | 2, 8, 18, 32, 17, 1 }}
{{Elementbox_section_physicalprop | color1=#ffc0c0 | color2=black }}
{{Elementbox_phase |
solid }}
{{Elementbox_density_gpcm3nrt | 21.45 }}
{{Elementbox_densityliq_gpcm3mp | 19.77 }}
{{Elementbox_meltingpoint | k=2041.4 | c=1768.3 | f=3214.9 }}
{{Elementbox_boilingpoint | k=4098 | c=3825 | f=6917 }}
{{Elementbox_heatfusion_kjpmol | 22.17 }}
{{Elementbox_heatvaporiz_kjpmol | 469 }}
{{Elementbox_heatcapacity_jpmolkat25 | 25.86 }}
{{Elementbox_vaporpressure_katpa | 2330 | (2550) | 2815 | 3143 | 3556 | 4094 | comment= }}
{{Elementbox_section_atomicprop | color1=#ffc0c0 | color2=black }}
{{Elementbox_crystalstruct | cubic face centered }}
{{Elementbox_oxistates | 2, 3, '''4'''
(mildly
base (chemistry) basic oxide) }}
{{Elementbox_electroneg_pauling | 2.28 }}
{{Elementbox_ionizationenergies2 | 870 | 1791 }}
{{Elementbox_atomicradius_pm |
1 E-10 m 135 }}
{{Elementbox_atomicradiuscalc_pm |
1 E-10 m 177 }}
{{Elementbox_covalentradius_pm |
1 E-10 m 128 }}
{{Elementbox_vanderwaalsrad_pm |
1 E-10 m 175 }}
{{Elementbox_section_miscellaneous | color1=#ffc0c0 | color2=black }}
{{Elementbox_magnetic |
paramagnetism paramagnetic }}
{{Elementbox_eresist_ohmmat20 | 105 n}}
{{Elementbox_thermalcond_wpmkat300k | 71.6 }}
{{Elementbox_thermalexpansion_umpmkat25 | 8.8 }}
{{Elementbox_speedofsound_rodmpsatrt | 2800 }}
{{Elementbox_youngsmodulus_gpa | 168 }}
{{Elementbox_shearmodulus_gpa | 61 }}
{{Elementbox_bulkmodulus_gpa | 230 }}
{{Elementbox_poissonratio | 0.38 }}
{{Elementbox_mohshardness | 3.5 }}
{{Elementbox_vickershardness_mpa | 549 }}
{{Elementbox_brinellhardness_mpa | 392 }}
{{Elementbox_cas_number | 7440-06-4 }}
{{Elementbox_isotopes_begin | isotopesof=platinum | color1=#ffc0c0 | color2=black }}
{{Elementbox_isotopes_decay | mn=190 | sym=Pt
| na=0.01% | hl=6.5×10
11 year y
| dm=
alpha decay α | de=3.18 | pn=186 | ps=
osmium Os }}
{{Elementbox_isotopes_decay | mn=191 | sym=Pt
| na=
synthetic radioisotope syn | hl=2.96 d
| dm=
electron capture ε | de=? | pn=191 | ps=
iridium Ir }}
{{Elementbox_isotopes_stable | mn=192 | sym=Pt | na=0.79% | n=114 }}
{{Elementbox_isotopes_decay | mn=193
Nuclear isomer m | sym=Pt
| na=
synthetic radioisotope syn | hl=4.33 d
| dm=
Internal conversion IT | de=0.1355
Conversion electron e | pn=193 | ps=
platinum Pt }}
{{Elementbox_isotopes_decay | mn=193 | sym=Pt
| na=
synthetic radioisotope syn | hl=50
year y
| dm=
electron capture ε | de=? | pn=193 | ps=
iridium Ir }}
{{Elementbox_isotopes_stable | mn=194 | sym=Pt | na=32.9% | n=116 }}
{{Elementbox_isotopes_decay | mn=195
Nuclear isomer m | sym=Pt
| na=
synthetic radioisotope syn | hl=4.02 d
| dm=
Internal conversion IT | de=0.1297
Conversion electron e | pn=195 | ps=
platinum Pt }}
{{Elementbox_isotopes_stable | mn=195 | sym=Pt | na=33.8% | n=117 }}
{{Elementbox_isotopes_stable | mn=196 | sym=Pt | na=25.3% | n=118 }}
{{Elementbox_isotopes_decay | mn=197
Nuclear isomer m | sym=Pt
| na=
synthetic radioisotope syn | hl=1.59 h
| dm=
Internal conversion IT | de=0.3465 | pn=197 | ps=
platinum Pt }}
{{Elementbox_isotopes_decay | mn=197 | sym=Pt
| na=
synthetic radioisotope syn | hl=19.8913 h
| dm=
beta emission β- | de=0.719 | pn=197 | ps=
gold Au }}
{{Elementbox_isotopes_stable | mn=198 | sym=Pt | na=7.2% | n=120 }}
{{Elementbox_isotopes_end}}
{{Elementbox_footer | color1=#ffc0c0 | color2=black }}
'''Platinum''' 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
jewellery, laboratory equipment,
electrical contacts, dentistry, and
automobile emissions control devices.
Notable characteristics
Image:Platinum nuggets.jpg left|thumb|An assortment of native platinum nuggets
The
metal appears silvery-white when pure, and firm. The metal is
corrosion-resistant. The
catalyst catalytic properties of the six
platinum family metals are outstanding (a mixture of
hydrogen and
oxygen 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
18th 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
oxidation oxidise in air at any temperature, but can be corroded by
cyanides,
halogens,
sulfur, and caustic
alkalis. This metal is insoluble in
hydrochloric acid 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.
Applications
* 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
Intercalation (chemistry) 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,
*
electrodes for use in
electrolysis.
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
Italy 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
Philip V of Spain 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
alchemy alchemical symbol for platinum (shown below) was made by joining the symbols of silver and gold.
image:platinum-symbol.png left|75px|Alchemical symbol for platinum
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
Bureau International des Poids et Mesures in
Sèvres,
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
Standard hydrogen electrode.
Occurrence
Image:PlatinumOreUSGOV.jpg thumb|left|Platinum ore
Platinum is an extremely rare metal, occurring as only 5
parts per billion ppb in the
Earth's
crust (geology) crust.
Platinum is often found free in areas of the
Americas and
alloy alloyed with
iridium as
platiniridium. The platinum
arsenide,
sperrylite (PtAs
2), 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.
Platinum, often accompanied by small amounts of other
platinum family metals, occurs in
alluvium alluvial Placer mining placer deposits in the
Witwatersrand of South Africa,
Colombia,
Ontario, the
Ural Mountains, and in certain western
United States 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
parts per million ppm in the ore.
Isotopes
Naturally occurring platinum is composed of five stable
isotopes and one
radioisotope, Pt-190, which has a very long
half-life (over 6 billion years or 190
second Ps). There are also many other
radioisotopes with the most stable being Pt-193 with a half-life of 50 years.
Precautions
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
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" (a higher certification of "Diamond" does exist, however). 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 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.
References
-
Los Alamos National Laboratory - Platinum
* ''[http://chartofthenuclides.com/default.html Nuclides and Isotopes] Fourteenth Edition: Chart of the Nuclides'', General Electric Company, 1989
-
Jefferson Lab - The Element Platinum
See also
*
Platinum coin
*
Precious metal
*
:Category:Platinum compounds Platinum compounds.''
External links
{{Commons|Platinum}}
{{wiktionary|platinum}}
-
The Platinum Group Metals Database
-
A balanced historical account of the sequence of discoveries of platinum; illustrated.
-
WebElements.com - Platinum
-
Platinum Metals Review E-Journal
-
Platinum Guild International
Category:Platinum
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Platinum Pt
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This category contains articles related to
platinum, a
chemical element and
precious metal.
Category:Chemical elements
Category:Transition metals
Category:Precious metals
*** Shopping-Tip: Platinum
