78
  Pt  
195.078000
Platinum

Name: Platinum
Symbol: Pt
Atomic Number: 78
AtomicWeight: 195.078000
Family: Transition Metals
CAS RN: 7440-06-4
Description: A silvery-white malleable and ductile metal.
State (25C): Solid
Oxidation states: +1, +2, +3,  +4

Molar Volume: 9.09 cm3/mole
Valence Electrons: 5d96s1

Boiling Point:  4100K, 3827C, 6921F
Melting Point:
2045K, 1772C, 3222F
Electrons Energy Level: 2, 8, 18, 32, 17, 1
Isotopes: 32 + 5 Stable
Heat of Vaporization: 510 kJ/mol
Heat of Fusion: 19.6 kJ/mol
Density: 21.45 g/cm3 @ 300K
Specific Heat: 0.13 J/gK
Atomic Radius: 1.83
Ionic Radius: 0.625
Electronegativity: 2.28 (Pauling); 1.44 (Allrod Rochow)
Vapor Pressure: 0.0312 Pa @ 1772C

1s2 2s2p6 3s2p6d10 4s2p6d10f14 5s2p6d9 6s1

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 Darin (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."

75px-Platinum-symbol.jpg (2335 bytes)

The alchemical symbol for platinum was made by joining the symbols of silver and gold.

Platinum was discussed by astronomer Antonio de Uloa and Don Jorge Juan y Santicilia (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.

platinum1.jpg (1640 bytes) platinum2.jpg (1247 bytes)
Alchemical Symbols, Platinum

Characteristics

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.

1s2
2s2 2p6
3s2 3p6 3d10
4s2 4p6 4d10 4f14
5s2 5p6 5d9
6s1

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.  In the 18th century, platinum's rarity made King Louis XV of France declare it the only metal fit for a king.

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.

Occurrence

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, Columbia, Ontario, the Ural Mountains, and in certain western Amercian 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.

Applications

Platinum is widely used as a catalyst.  It will convert methyl alcohol vapors (CH4O) into formaldehyde (CH2O) on contact, glowing red hot in the process.  This effect is used to make small hand warmers.  Platinum is also used in a device called a catalytic converter, a device found in the exhaust systems of most cars.  Catalytic converters combine carbon monoxide (CO) and unburned fuel from a car's exhaust with oxygen from the air, forming carbon dioxide (CO2) and water vapor (H2O). Platinum is also used as a catalyst in the production of sulfuric acid (H2SO4) and in the cracking of petroleum products.   Fuel cells, devices that combine hydrogen and oxygen to produce electricity and water, also use platinum as a catalyst.

Rarity & 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.

World Production

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

Compounds

Platinum Arsenide, Sperrylite PtAs2 Cooperite, (Pt,Pd,Ni)S

Isotopes

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Isotope  
Atomic Mass
 
Half-Life
166Pt 165.99486 300 s
167Pt 166.99298 700 s
168Pt 167.98815 2.00 ms
169Pt 168.98672 3.7 ms
170Pt 169.982495 14.0 ms
171Pt 170.98124 51 ms
172Pt 171.977347 98.4 ms
173Pt 172.97644 365 ms
174Pt 173.972819 0.889 seconds
175Pt 174.972421 2.53 seconds
176Pt 175.968945 6.33 seconds
177Pt 176.968469 10.6 seconds
178Pt 177.965649 21.1 seconds
179Pt 178.965363 21.2 seconds
180Pt 179.963031 56 seconds
181Pt 180.963097 52.0 seconds
182Pt 181.961171 2.2 minutes
183Pt 182.961597 6.5 minutes
184Pt 183.959922 17.3 minutes
185Pt 184.96062 70.9 minutes
186Pt 185.959351 2.08 hours
187Pt 186.96059 2.35 hours
188Pt 187.959395 10.2 days
189Pt 188.960834 10.87 hours
190Pt 189.959932 6.5 x 1011 years
191Pt 190.961677 2.862 days
192Pt 191.9610380 Stable
193Pt 192.9629874 50 years
194Pt 193.9626803 Stable
195Pt 194.9647911 Stable
196Pt 195.9649515 Stable
197Pt 196.9673402 19.8915 hours
198Pt 197.967893 Stable
199Pt 198.970593 30.80 minutes
200Pt 199.971441 12.5 hours
201Pt 200.97451 2.5 minutes
202Pt 201.97574 44 hours

Precautions

40px-Skull_and_crossbones.svg.jpg (1420 bytes) 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.

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, although they also cause cumulative, irreversible kidney damage, as well as deafness.

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), 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.

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Platinum Data
 

Atomic Structure

  • Atomic Radius: 1.83
  • Atomic Volume: 9.1cm3/mol
  • Covalent Radius: 1.3
  • Cross Section (Thermal Neutron Capture) Barns: 0.96
  • Crystal Structure: Cubic face centered
  • Electron Configuration:
    1s2 2s2p6 3s2p6d10 4s2p6d10f14 5s2p6d9 6s1
  • Electrons per Energy Level: 2, 8, 18, 32, 17, 1
  • Ionic Radius: 0.625
  • Filling Orbital: 5d9
  • Number of Electrons (with no charge): 78
  • Number of Neutrons (most common/stable nuclide): 117
  • Number of Protons: 78
  • Oxidation States: 2, 4
  • Valence Electrons: 5d9 6s1

Chemical Properties

  • Electrochemical Equivalent: 1.8197 g/amp-hr
  • Electron Work Function: 5.65eV
  • Electronegativity: 2.28 (Pauling); 1.44 (Allrod Rochow)
  • Heat of Fusion: 19.6 kJ/mol
  • Incompatibilities:
    Aluminum, acetone, arsenic, ethane, hydrazine, hydrogen peroxide, lithium, phosphorus, selenium, tellurium, various fluorides
  • Ionization Potential
    • First: 9
    • Second: 18.563
  • Valence Electron Potential )-eV): 92.2

Physical Properties

  • Atomic Mass Average: 195.08
  • Boiling Point: 4100K, 3827C, 6921F
  • Coefficient of Lineal Thermal Expansion/K-1: 9E-6
  • Conductivity
    Electrical: 0.0966 106/cm
    Thermal: 0.716 W/cmK
  • Density: 21.45 g/cm3 @ 300K
  • Description:
    Silver white transition metal.
  • Elastic Modulus:
    • Bulk: 276/GPa
    • Rigidity: 60.9/GPa
    • Youngs: 170/GPa
  • Enthalpy of Atomization: 565 kJ/mole @ 25C
  • Enthalpy of Fusion: 19.7 kJ/mole
  • Enthalpy of Vaporization: 510.5 kJ/mole
  • Flammablity Class: Non-combustible solid (except as dust)
  • Freezing Point: see melting point
  • Hardness Scale
    • Brinell: 392 MN m-2
    • Mohs: 3.5
    • Vickers: 549 MN m-2
  • Heat of Vaporization: 510 kJ/mol
  • Melting Point: 2045K, 1772C, 3222F
  • Molar Volume: 9.09 cm3/mole
  • Optical Reflectivity: 73%
  • Physical State (at 20C & 1atm): Solid
  • Specific Heat: 0.13 J/gK
  • Vapor Pressure: 0.0312 Pa @ 1772C

Regulatory / Health

  • CAS Number
    • 7440-06-4
  • RTECS: TP2160000
  • OSHA Permissible Exposure Limit (PEL)
    • No limits set by OSHA
  • OSHA PEL Vacated 1989
    • TWA: 1 mg/m3
  • NIOSH Recommended Exposure Limit (REL)
    • TWA: 1 mg/m3
  • Routes of Exposure: Inhalation; Ingestion; Skin and/or eye contact
  • Target Organs: Eyes, skin, respiratory system
  • Levels In Humans:
    Note: this data represents naturally occuring levels of elements in the typical human, it DOES NOT represent recommended daily allowances.
    • Blood/mg dm-3: n/a
    • Bone/p.p.m: n/a
    • Liver/p.p.m: n/a
    • Muscle/p.p.m: n/a
    • Daily Dietary Intake: n/a
    • Total Mass In Avg. 70kg human: n/a

Who / Where / When / How

  • Discoverer: Known to pre-Columbian South Americans. Taken to Europe around 1750
  • Discovery Location: South America
  • Discovery Year: Unknown
  • Name Origin:
    Spanish: platina (little silver).
  • Abundance:
    • Earth's Crust/p.p.m.: 0.001
    • Seawater/p.p.m.:
      • Atlantic Suface: N/A
      • Atlantic Deep: N/A
      • Pacific Surface: 1.1E-07
      • Pacific Deep: 2.7E-07
    • Atmosphere/p.p.m.: N/A
    • Sun (Relative to H=1E12): 56.2
  • Sources:
    Produced from platinum ore or native platinum deposits. Primary mining areas are Urals in Russia, Canada, South Africa Columbia and Peru. Annual world wide production is around 30 tons.
  • Uses:
    Used in jewelry, to make crucibles, special containers, as a catalyst, in dental crowns, as an anti-tumor agent and to make standard weights and measures. It is also combined with cobalt to produce very strong magnets.
  • Additional Notes:
    Some sources attribute the discovery of platinum to Antonio de Ulloa of Spain in 1735 or Wood in 1741, however, it had been known to and used by the pre-Columbian Indians in South America long before that time. For this reason we have opted to credit the first users of platinum with the discovery, not the European explorers/scientists that "rediscovered" it and brought it to Europe.

Ionization Energy (eV): 9.0 eV
Estimated Crustal Abundance: 510-3 milligrams per kilogram
Estimated Oceanic Abundance: unknown

Transition Metals
Group 3
(IIIB)
4
(IVB)
5
(VB)
6
(VIB)
7
(VIIB)
8
(VIIIB)
9
(VIIIB)
10 (VIIIB) 11
(IB)
12
(IIB)
Period 4 21
Sc
44.95
22
Ti
47.86
23
V
50.94
24
Cr
51.99
25
Mn
54.93
26
Fe
55.84
27
Co
58.93
28
Ni
58.69
29
Cu
63.54
30
Zn
65.39
Period 5 39
Y
88.90
40
Zr
91.22
41
Nb
92.90
42
Mo
95.94
43
Tc
98.00
44
Ru
101.0
45
Rh
102.9
46
Pd
106.4
47
Ag
107.8
48
Cd
112.4
Period 6 57
La
138.9
72
Hf
178.4
73
Ta
180.9
74
W
183.8
75
Re
186.2
76
Os
190.2
77
Ir
192.2
78
Pt
195.0
79
Au
196.9
80
Hg
200.5
Period 7 89
Ac
227.0
104
Rf
261.0
105
Db
262.0
106
Sg
266.0
107
Bh
264.0
108
Hs
269.0
109
Mt
268.0
110
Ds
269.0
111
Rg
272.0
112
Uub
277.0