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Encyclopedia > Iridium
77 osmiumiridiumplatinum
Rh

Ir

Mt
General
Name, Symbol, Number iridium, Ir, 77
Chemical series transition metals
Group, Period, Block 9, 6, d
Appearance silvery white
Standard atomic weight 192.217(3) g·mol−1
Electron configuration [Xe] 4f14 5d7 6s2
Electrons per shell 2, 8, 18, 32, 15, 2
Physical properties
Phase solid
Density (near r.t.) 22.42 g·cm−3
Liquid density at m.p. 19 g·cm−3
Melting point 2739 K
(2466 °C, 4471 °F)
Boiling point 4701 K
(4428 °C, 8002 °F)
Heat of fusion 41.12 kJ·mol−1
Heat of vaporization 563 kJ·mol−1
Heat capacity (25 °C) 25.10 J·mol−1·K−1
Vapor pressure
P(Pa) 1 10 100 1 k 10 k 100 k
at T(K) 2713 2957 3252 3614 4069 4659
Atomic properties
Crystal structure cubic face centered
Oxidation states 2, 3, 4, 6
(mildly basic oxide)
Electronegativity 2.20 (scale Pauling)
Ionization energies 1st: 880 kJ/mol
2nd: 1600 kJ/mol
Atomic radius 135 pm
Atomic radius (calc.) 180 pm
Covalent radius 137 pm
Miscellaneous
Magnetic ordering no data
Electrical resistivity (20 °C) 47.1 n Ω·m
Thermal conductivity (300 K) 147 W·m−1·K−1
Thermal expansion (25 °C) 6.4 µm·m−1·K−1
Speed of sound (thin rod) (20 °C) 4825 m/s
Young's modulus 528 GPa
Shear modulus 210 GPa
Bulk modulus 320 GPa
Poisson ratio 0.26
Mohs hardness 6.5
Vickers hardness 1760 MPa
Brinell hardness 1670 MPa
CAS registry number 7439-88-5
Selected isotopes
Main article: Isotopes of iridium
iso NA half-life DM DE (MeV) DP
189Ir syn 13.2 d ε 0.532 189Os
190Ir syn 11.8 d ε 2.000 190Os
191Ir 37.3% Ir is stable with 114 neutrons
192Ir syn 73.83 d β 1.460 192Pt
ε 1.046 192Os
192mIr syn 241 y IT 0.155 192Ir
193Ir 62.7% Ir is stable with 116 neutrons
194Ir syn 19.3 h β< 2.247 194Pt
195Ir syn 2.5 h β< 1.120 195Pt
References

Iridium (pronounced /ɪˈrɪdiəm/) is a chemical element that has the symbol Ir and atomic number 77. A dense, very hard, brittle, silvery-white transition metal of the platinum family, iridium is used in high strength alloys that can withstand high temperatures and occurs in natural alloys with platinum or osmium. Iridium is notable for being the most corrosion resistant element known and for its significance in the determination of the probable cause of the extinction, by a meteorite strike, of the dinosaurs. It is used in high temperature apparati, electrical contacts, and as a hardening agent for platinum. An Iridium phone (without the aerial) The Iridium satellite constellation is a system of 66 active communication satellites and spares around the Earth. ... General Name, Symbol, Number osmium, Os, 76 Chemical series transition metals Group, Period, Block 8, 6, d Appearance silvery, blue cast Standard atomic weight 190. ... General Name, Symbol, Number platinum, Pt, 78 Chemical series transition metals Group, Period, Block 10, 6, d Appearance grayish white Standard atomic weight 195. ... General Name, Symbol, Number rhodium, Rh, 45 Chemical series transition metals Group, Period, Block 9, 5, d Appearance silvery white metallic Standard atomic weight 102. ... General Name, Symbol, Number meitnerium, Mt, 109 Chemical series transition metals Group, Period, Block 9, 7, d Appearance unknown, probably silvery white or metallic gray Atomic mass (268) g·mol−1 Electron configuration perhaps [Rn] 5f14 6d7 7s2 (guess based on iridium) Electrons per shell 2, 8, 18, 32, 32... description Image de lélément dans le tableau périodique des éléments source image produite pour Wikipédia par leurs auteurs auteurs Daniel Mayer (w:en:Maveric149) and/or Arnaud Gaillard (Greatpatton) copyright GFDL version haute définition Image:Ir-TableImage-BIG.png File links The following pages... This is a standard display of the periodic table of the elements. ... An extended periodic table was suggested by Glenn T. Seaborg in 1969. ... This is a list of chemical elements, sorted by name and color coded according to type of element. ... A table of chemical elements ordered by atomic number and color coded according to type of element. ... A group, also known as a family, is a vertical column in the periodic table of the chemical elements. ... In chemistry, the term transition metal (sometimes also called a transition element) has two possible meanings: It commonly refers to any element in the d-block of the periodic table, including zinc, cadmium and mercury. ... A group, also known as a family, is a vertical column in the periodic table of the chemical elements. ... In the periodic table of the elements, a period is a horizontal row of the table. ... A block of the periodic table of elements is a set of adjacent groups. ... The Group 9 elements are: Cobalt (27) Rhodium (45) Iridium (77) Meitnerium (109) Color coding for these atomic numbers: At room temperature, all are solid; red indicates item is synthetic and does not occur naturally. ... A period 6 element is one of the chemical elements in the sixth row (or period) of the periodic table of the elements, including the Lanthanides. ... D Block is a rap group based in Yonkers, New York. ... Color is an important part of the visual arts. ... Image File history File linksMetadata Download high resolution version (1521x1293, 360 KB) Summary Iridium foil. ... The atomic mass (ma) is the mass of an atom at rest, most often expressed in unified atomic mass units. ... To help compare different orders of magnitude we list here masses between 60. ... Hydrogen = 1 List of Elements in Atomic Number Order. ... Electron atomic and molecular orbitals In atomic physics and quantum chemistry, the electron configuration is the arrangement of electrons in an atom, molecule, or other physical structure (, a crystal). ... General Name, Symbol, Number xenon, Xe, 54 Chemical series noble gases Group, Period, Block 18, 5, p Appearance colorless Standard atomic weight 131. ... For other uses, see Electron (disambiguation). ... Example of a sodium electron shell model An electron shell, also known as a main energy level, is a group of atomic orbitals with the same value of the principal quantum number n. ... In the physical sciences, a phase is a set of states of a macroscopic physical system that have relatively uniform chemical composition and physical properties (i. ... For other uses, see Solid (disambiguation). ... For other uses, see Density (disambiguation). ... For other uses, see Room temperature (disambiguation). ... For other uses, see Density (disambiguation). ... The melting point of a crystalline solid is the temperature range at which it changes state from solid to liquid. ... The melting point of a crystalline solid is the temperature range at which it changes state from solid to liquid. ... For other uses, see Kelvin (disambiguation). ... Celsius is, or relates to, the Celsius temperature scale (previously known as the centigrade scale). ... For other uses, see Fahrenheit (disambiguation). ... Italic text This article is about the boiling point of liquids. ... For other uses, see Kelvin (disambiguation). ... Celsius is, or relates to, the Celsius temperature scale (previously known as the centigrade scale). ... For other uses, see Fahrenheit (disambiguation). ... Standard enthalpy change of fusion of period three. ... The joule per mole (symbol: J·mol-1) is an SI derived unit of energy per amount of material. ... The standard enthalpy change of vaporization, ΔvHo, also (less correctly) known as the heat of vaporization is the energy required to transform a given quantity of a substance into a gas. ... The joule per mole (symbol: J·mol-1) is an SI derived unit of energy per amount of material. ... To meet Wikipedias quality standards, this article or section may require cleanup. ... Vapor pressure is the pressure of a vapor in equilibrium with its non-vapor phases. ... Enargite crystals In mineralogy and crystallography, a crystal structure is a unique arrangement of atoms in a crystal. ... The oxidation number of an element in a molecule or complex is the charge that it would have if all the ligands (basically, atoms that donate electrons) were removed along with the electron pairs that were shared with the central atom[1]. It means that the oxidation number is the... Acids and bases: Acid-base extraction Acid-base reaction Acid dissociation constant Acidity function Buffer solutions pH Proton affinity Self-ionization of water Acids: Lewis acids Mineral acids Organic acids Strong acids Superacids Weak acids Bases: Lewis bases Organic bases Strong bases Superbases Non-nucleophilic bases Weak bases edit In... Electronegativity is a measure of the ability of an atom or molecule to attract electrons in the context of a chemical bond. ... The ionization potential, ionization energy or EI of an atom or molecule is the energy required to remove one mole of electrons from one mole of isolated gaseous atoms or ions. ... The joule per mole (symbol: J·mol-1) is an SI derived unit of energy per amount of material. ... Atomic radius: Ionic radius Covalent radius Metallic radius van der Waals radius edit Atomic radius, and more generally the size of an atom, is not a precisely defined physical quantity, nor is it constant in all circumstances. ... You have big harry skanky balls ... One picometre is defined as 1x10-12 metres, in standard units. ... You have big harry skanky balls ... Atomic radius: Ionic radius Covalent radius Metallic radius van der Waals radius edit The covalent radius, rcov, is a measure of the size of atom which forms part of a covalent bond. ... You have big harry skanky balls ... For other senses of this word, see magnetism (disambiguation). ... // Headline text POOP!! Danny Hornsby (also known as Gnome) is a measure indicating how strongly a Gnome can opposes the flow of electric current. ... K value redirects here. ... During heat transfer, the energy that is stored in the intermolecular bonds between atoms changes. ... This page is about the physical speed of sound waves in a medium. ... Metre per second (U.S. spelling: meter per second) is an SI derived unit of both speed (scalar) and velocity (vector), defined by distance in metres divided by time in seconds. ... In solid mechanics, Youngs modulus (E) is a measure of the stiffness of a given material. ... In materials science, shear modulus, G, or sometimes S or μ, sometimes referred to as the modulus of rigidity, is defined as the ratio of shear stress to the shear strain:[1] where = shear stress; force acts on area ; = shear strain; length changes by amount . ... The bulk modulus (K) of a substance essentially measures the substances resistance to uniform compression. ... Figure 1: Rectangular specimen subject to compression, with Poissons ratio circa 0. ... The Mohs scale of mineral hardness characterizes the scratch resistance of various minerals through the ability of a harder material to scratch a softer material. ... A Vickers hardness tester The Vickers hardness test was developed in the early 1920s as an alternative method to measure the hardness of materials. ... The Brinell scale characterises the indentation hardness of materials through the scale of penetration of an indenter, loaded on a material test-piece. ... CAS registry numbers are unique numerical identifiers for chemical compounds, polymers, biological sequences, mixtures and alloys. ... Iridium (Ir) Standard atomic mass: 192. ... For other uses, see Isotope (disambiguation). ... Natural abundance refers to the prevalence of different isotopes of an element as found in nature. ... Half-Life For a quantity subject to exponential decay, the half-life is the time required for the quantity to fall to half of its initial value. ... Radioactive decay is the process in which an unstable atomic nucleus loses energy by emitting radiation in the form of particles or electromagnetic waves. ... The decay energy is the energy released by a nuclear decay. ... The electronvolt (symbol eV) is a unit of energy. ... In nuclear physics, a decay product, also known as a daughter product, is a nuclide resulting from the radioactive decay of a parent or precursor nuclide. ... A Synthetic radioisotope is a radionuclide that is not found in nature: no natural process or mechanism exists which produces it, or it is so unstable that it decays away in a very short period of time. ... Electron capture is a decay mode for isotopes that will occur when there are too many protons in the nucleus of an atom, and there isnt enough energy to emit a positron; however, it continues to be a viable decay mode for radioactive isotopes that can decay by positron... General Name, Symbol, Number osmium, Os, 76 Chemical series transition metals Group, Period, Block 8, 6, d Appearance silvery, blue cast Standard atomic weight 190. ... A Synthetic radioisotope is a radionuclide that is not found in nature: no natural process or mechanism exists which produces it, or it is so unstable that it decays away in a very short period of time. ... Electron capture is a decay mode for isotopes that will occur when there are too many protons in the nucleus of an atom, and there isnt enough energy to emit a positron; however, it continues to be a viable decay mode for radioactive isotopes that can decay by positron... General Name, Symbol, Number osmium, Os, 76 Chemical series transition metals Group, Period, Block 8, 6, d Appearance silvery, blue cast Standard atomic weight 190. ... Stable isotopes are chemical isotopes that are not radioactive. ... This article or section does not adequately cite its references or sources. ... A Synthetic radioisotope is a radionuclide that is not found in nature: no natural process or mechanism exists which produces it, or it is so unstable that it decays away in a very short period of time. ... In nuclear physics, beta decay (sometimes called neutron decay) is a type of radioactive decay in which a beta particle (an electron or a positron) is emitted. ... General Name, Symbol, Number platinum, Pt, 78 Chemical series transition metals Group, Period, Block 10, 6, d Appearance grayish white Standard atomic weight 195. ... Electron capture is a decay mode for isotopes that will occur when there are too many protons in the nucleus of an atom, and there isnt enough energy to emit a positron; however, it continues to be a viable decay mode for radioactive isotopes that can decay by positron... General Name, Symbol, Number osmium, Os, 76 Chemical series transition metals Group, Period, Block 8, 6, d Appearance silvery, blue cast Standard atomic weight 190. ... A nuclear isomer is a metastable or isomeric state of an atom caused by the excitation of a proton or neutron in its nucleus so that it requires a change in spin before it can release its extra energy. ... A Synthetic radioisotope is a radionuclide that is not found in nature: no natural process or mechanism exists which produces it, or it is so unstable that it decays away in a very short period of time. ... A year (from Old English gÄ“r) is the time between two recurrences of an event related to the orbit of the Earth around the Sun. ... Internal conversion or isomeric transition is the act of returning from an excited state by an atom or molecule. ... Stable isotopes are chemical isotopes that are not radioactive. ... This article or section does not adequately cite its references or sources. ... A Synthetic radioisotope is a radionuclide that is not found in nature: no natural process or mechanism exists which produces it, or it is so unstable that it decays away in a very short period of time. ... In nuclear physics, beta decay (sometimes called neutron decay) is a type of radioactive decay in which a beta particle (an electron or a positron) is emitted. ... General Name, Symbol, Number platinum, Pt, 78 Chemical series transition metals Group, Period, Block 10, 6, d Appearance grayish white Standard atomic weight 195. ... A Synthetic radioisotope is a radionuclide that is not found in nature: no natural process or mechanism exists which produces it, or it is so unstable that it decays away in a very short period of time. ... In nuclear physics, beta decay (sometimes called neutron decay) is a type of radioactive decay in which a beta particle (an electron or a positron) is emitted. ... General Name, Symbol, Number platinum, Pt, 78 Chemical series transition metals Group, Period, Block 10, 6, d Appearance grayish white Standard atomic weight 195. ... Recommended values for many properties of the elements, together with various references, are collected on these data pages. ... The periodic table of the chemical elements A chemical element, or element, is a type of atom that is defined by its atomic number; that is, by the number of protons in its nucleus. ... See also: List of elements by atomic number In chemistry and physics, the atomic number (also known as the proton number) is the number of protons found in the nucleus of an atom. ... In chemistry, the term transition metal (sometimes also called a transition element) has two possible meanings: It commonly refers to any element in the d-block of the periodic table, including zinc, cadmium and mercury. ... The platinum group or platinum metals is the collective name sometimes used for six chemical elements within the periodic table. ... An alloy is a homogeneous hybrid of two or more elements, at least one of which is a metal, and where the resulting material has metallic properties. ... General Name, Symbol, Number platinum, Pt, 78 Chemical series transition metals Group, Period, Block 10, 6, d Appearance grayish white Standard atomic weight 195. ... General Name, Symbol, Number osmium, Os, 76 Chemical series transition metals Group, Period, Block 8, 6, d Appearance silvery, blue cast Standard atomic weight 190. ... Badlands near Drumheller, Alberta where erosion has exposed the KT boundary. ... Orders & Suborders Saurischia Sauropodomorpha Theropoda Ornithischia Thyreophora Ornithopoda Marginocephalia Dinosaurs were vertebrate animals that dominated the terrestrial ecosystem for over 160 million years, first appearing approximately 230 million years ago. ...

Contents

Notable characteristics

A platinum group metal, iridium is white, resembling platinum, but with a slight yellowish cast. Due to its extreme hardness and brittle properties, iridium is difficult to machine, form, or work. It is the most corrosion-resistant metal known: iridium cannot be attacked by any acids or by aqua regia, but it can be attacked by molten salts, such as NaCl and NaCN. The platinum group or platinum metals is the collective name sometimes used for six chemical elements within the periodic table. ... This article is about metallic materials. ... General Name, Symbol, Number platinum, Pt, 78 Chemical series transition metals Group, Period, Block 10, 6, d Appearance grayish white Standard atomic weight 195. ... For the hazard, see corrosive. ... For other uses, see Acid (disambiguation). ... Freshly prepared aqua regia is colorless, but it turns orange within seconds. ... For other uses, see Salt (disambiguation). ... R-phrases 36 S-phrases none Flash point Non-flammable Related Compounds Other anions NaF, NaBr, NaI Other cations LiCl, KCl, RbCl, CsCl, MgCl2, CaCl2 Related salts Sodium acetate Supplementary data page Structure and properties n, εr, etc. ... Sodium cyanide is a highly toxic chemical compound, also known as sodium salt of hydrocyanic acid and cyanogran. ...


The measured density of iridium is only slightly lower than that of osmium, which is often listed as the most dense element known. However, calculations of density from the space lattice may produce more reliable data for these elements than actual measurements and give a density of 22,650 kg/m³ for iridium versus 22,610 kg/m³ for osmium. Definitive selection between the two is therefore not possible at this time. For other uses, see Density (disambiguation). ... General Name, Symbol, Number osmium, Os, 76 Chemical series transition metals Group, Period, Block 8, 6, d Appearance silvery, blue cast Standard atomic weight 190. ... Rose des Sables (Sand Rose), formed of gypsum crystals In mineralogy and crystallography, a crystal structure is a unique arrangement of atoms in a crystal. ... Kilogram per cubic metre is the SI measure of density and is represented as kg/m³, where kg stands for kilogram and m³ stands for cubic metre. ...


Applications

The principal use of iridium is as a hardening agent in platinum alloys. Other uses:

  • For making crucibles and devices that require high temperatures.
  • Electrical contacts (notable example: Pt/Ir spark plugs).
  • Osmium/iridium alloys are used for compass bearings.
  • Iridium is commonly used in complexes like Ir(mppy)3 and other complexes in polymer LED technology to increase the efficiency from 25% to almost 100% due to triplet harvesting.
  • Used in high-dose-radiation therapy for the treatment of prostate and other forms of cancer
  • Iridium is used as a catalyst for carbonylation of methanol to produce acetic acid
  • Iridium is used in supercolliders in the production of antimatter, specifically antiprotons

At one time iridium, as an alloy with platinum, was used in bushing the vents of heavy ordnance, and in a finely powdered condition (iridium black), for painting porcelain black. For other uses, see Crucible (disambiguation). ... This article or section should include material from Spark gap A spark plug is an electrical device that fits into the cylinder head of some internal combustion engines and ignites compressed aerosol gasoline by means of an electric spark. ... This article is about the navigational instrument. ... —a complex is different from complicated or composed, the complex is more than the sum of its parts Look up complex in Wiktionary, the free dictionary. ... A polymer light-emitting diode is an electroluminescent polymer that emits light when subjected to an electric current. ... It has been suggested that this article or section be merged into Catalysis. ... Carbonyl group In organic chemistry, a carbonyl group is a functional group composed of a carbon atom double-bonded to an oxygen atom : C=O. The term carbonyl can also refer to carbon monoxide as a ligand in an inorganic or organometallic complex (a metal carbonyl, e. ... Methanol, also known as methyl alcohol, carbinol, wood alcohol, wood naptha or wood spirits, is a chemical compound with chemical formula CH3OH. It is the simplest alcohol, and is a light, volatile, colourless, flammable, poisonous liquid with a distinctive odor that is somewhat milder and sweeter than ethanol (ethyl alcohol). ... R-phrases , S-phrases , , , Flash point 43 °C Related Compounds Related carboxylic; acids Formic acid; Propionic acid; Butyric acid Related compounds acetamide; ethyl acetate; acetyl chloride; acetic anhydride; acetonitrile; acetaldehyde; ethanol; thioacetic acid; acetylcholine; acetylcholinesterase Supplementary data page Structure and properties n, εr, etc. ... For the particle accelerator, see Superconducting Supercollider. ... For other senses of this term, see antimatter (disambiguation). ... The antiproton (aka pbar) is the antiparticle of the proton. ... For other uses, see Weapon (disambiguation). ... “Fine China” redirects here. ...


Iridium was used to tip some early twentieth century fountain pen nibs. The tip material in modern fountain pens is still conventionally called "iridium," although there is seldom any iridium in it.


History

Iridium was discovered in 1803 by British scientist Smithson Tennant in London, England along with osmium in the dark-coloured residue of dissolving crude platinum in aqua regia (a mixture of hydrochloric and nitric acid). The element was named after the Latin word for rainbow (iris; iridium means "of rainbows") because many of its salts are strongly coloured. 1803 was a common year starting on Saturday (see link for calendar). ... Smithson Tennant (November 30, 1761 - February 22, 1815) was an English chemist. ... This article is about the capital of England and the United Kingdom. ... For other uses, see England (disambiguation). ... General Name, Symbol, Number osmium, Os, 76 Chemical series transition metals Group, Period, Block 8, 6, d Appearance silvery, blue cast Standard atomic weight 190. ... General Name, Symbol, Number platinum, Pt, 78 Chemical series transition metals Group, Period, Block 10, 6, d Appearance grayish white Standard atomic weight 195. ... Freshly prepared aqua regia is colorless, but it turns orange within seconds. ... R-phrases , S-phrases , , Flash point Non-flammable. ... The chemical compound nitric acid (HNO3), also known as aqua fortis and spirit of nitre, is an aqueous solution of hydrogen nitrate (anhydrous nitric acid). ... For other uses, see Latin (disambiguation). ... For other uses, see Rainbow (disambiguation). ... For other meanings of the word salt see table salt or salt (disambiguation). ...


An alloy of 90% platinum and 10% iridium was used in 1889 to construct the standard metre bar and kilogramme mass, kept by the International Bureau of Weights and Measures near Paris. The metre bar was replaced as the definition of the fundamental unit of length in 1960 (see krypton), but the kilogram prototype is still the international standard of mass. Year 1889 (MDCCCLXXXIX) was a common year starting on Tuesday (link will display the full calendar) of the Gregorian calendar (or a common year starting on Sunday of the 12-day slower Julian calendar). ... This article is about the unit of length. ... The international prototype, made of platinum-iridium, which is kept at the BIPM under conditions specified by the 1st CGPM in 1889. ... The Bureau International des Poids et Mesures (International Bureau of Weights and Measures, or BIPM) is a standards organization, one of the three organizations established to maintain the SI system under the terms of the Metre Convention. ... This article is about the capital of France. ... Year 1960 (MCMLX) was a leap year starting on Friday (link will display full calendar) of the Gregorian calendar. ... For other uses, see Krypton (disambiguation). ...


K-T boundary

Main article: Cretaceous–Tertiary extinction event
Main article: K–T boundary

The K–T boundary of 65 million years ago, marking the temporal border between the Cretaceous and Tertiary eras of geological time, was identified by a thin stratum of iridium-rich clay. A team led by Luis Alvarez (1980) proposed an extraterrestrial origin for this iridium, attributing it to an asteroid or comet impact. Their theory is widely accepted to explain the demise of the dinosaurs. A large buried impact crater structure with an estimated age of about 65 million years was later identified near what is now Yucatán Peninsula. Dewey M. McLean and others argue that the iridium may have been of volcanic origin instead. The Earth's core is rich in iridium, and Piton de la Fournaise on Réunion, for example, is still releasing iridium today. Artists impression of a major impact event. ... Badlands near Drumheller, Alberta where erosion has exposed the KT boundary. ... Badlands near Drumheller, Alberta where erosion has exposed the KT boundary. ... // The Cretaceous Period is one of the major divisions of the geologic timescale, reaching from the end of the Jurassic Period (i. ... Tertiary geological time interval covers roughly the time span between the demise of the non-avian dinosaurs and beginning of the most recent Ice Age, approximately 65 million to 1. ... The geologic time scale is used by geologists and other scientists to describe the timing and relationships between events that have occurred during the history of the Earth. ... For other uses, see strata (novel) and strata title. ... Luis Walter Alvarez (June 13, 1911 &#8211; September 1, 1988) of San Francisco, California, USA, was a famed physicist who worked at the University of California, Berkeley. ... Year 1980 (MCMLXXX) was a leap year starting on Tuesday (link displays the 1980 Gregorian calendar). ... For other uses, see Asteroid (disambiguation). ... Comet Hale-Bopp Comet West For other uses, see Comet (disambiguation). ... Orders & Suborders Saurischia Sauropodomorpha Theropoda Ornithischia Thyreophora Ornithopoda Marginocephalia Dinosaurs were vertebrate animals that dominated the terrestrial ecosystem for over 160 million years, first appearing approximately 230 million years ago. ... The Yucatán peninsula as seen from space The Yucatán Peninsula, in Southeastern Mexico, separates the Caribbean Sea from the Gulf of Mexico. ... Cleveland Volcano in the Aleutian Islands of Alaska photographed from the International Space Station For other uses, see Volcano (disambiguation). ... This article is about Earth as a planet. ... Piton de la Fournaise (French: Peak of the Furnace) is a shield volcano on the eastern side of Réunion island (a French territory) in the Indian Ocean. ...


Occurrence

Iridium is found uncombined in nature with platinum and other platinum group metals in alluvial deposits. Naturally occurring iridium alloys include osmiridium and iridiosmium, both of which are mixtures of iridium and osmium. It is recovered commercially as a by-product from nickel mining and processing. Alluvium (from the Latin, alluvius, from alluere, to wash against) is soil or sediments deposited by a river or other running water. ... Osmiridium is an alloy of osmium and iridium with a trace of platinum and rhodium, found naturally or man-made. ... Please wikify (format) this article as suggested in the Guide to layout and the Manual of Style. ... For other uses, see Nickel (disambiguation). ...


Iridium is the rarest non-radioactive, non-noble gas element in the Earth's crust, but it is relatively common in meteorites. Iridium and osmium are the densest elements, and both are believed to have dropped below the Earth's crust toward the core when the Earth was young and molten. The concentration of iridium in meteorites matches the concentration of iridium in the Earth as a whole. This article is about Earth as a planet. ... Willamette Meteorite A meteorite is a natural object originating in outer space that survives an impact with the Earths surface without being destroyed. ... General Name, Symbol, Number osmium, Os, 76 Chemical series transition metals Group, Period, Block 8, 6, d Appearance silvery, blue cast Standard atomic weight 190. ...


Isotopes

Main article: isotopes of iridium

There are two natural isotopes of iridium, and many radioisotopes, the most stable radioisotope being Ir-192 with a half-life of 73.83 days. Ir-192 beta decays into platinum-192, while most of the other radioisotopes decay into osmium. Iridium (Ir) Standard atomic mass: 192. ... For other uses, see Isotope (disambiguation). ... A radionuclide is an atom with an unstable nucleus. ... Iridium-192 (symbol Ir192m) is an isotope of Iridium. ... Half-Life For a quantity subject to exponential decay, the half-life is the time required for the quantity to fall to half of its initial value. ... In nuclear physics, beta decay (sometimes called neutron decay) is a type of radioactive decay in which a beta particle (an electron or a positron) is emitted. ...


Precautions

Iridium metal is mostly non-toxic due to its relative unreactivity, but iridium compounds should be considered highly toxic.[citation needed]


References

External links

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Look up iridium in
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  Results from FactBites:
 
Iridium - definition of Iridium in Encyclopedia (675 words)
Iridium is notable for being the most corrosion resistant element known and for its association with the demise of the dinosaurs.
At one time iridium, as an alloy with platinum, was used in bushing the vents of heavy ordnance and, in a finely powdered condition (iridium fl), for painting porcelain fl.
Iridium (Latin iris meaning "rainbow", "iridium" means "of rainbows") was discovered in 1803 by Smithson Tennant in London, England along with osmium in the dark colored residue of dissolving crude platinum in aqua regia (a mixture of hydrochloric and nitric acid).
Iridium (satellite) - Wikipedia, the free encyclopedia (1386 words)
The Iridium satellites were, however, retained in orbit, and their services were re-established in 2001 by the newly founded Iridium Satellite LLC, owned by a group of private investors.
Iridium Satellite LLC claims to have approximately 137,500 subscribers as of September 30, 2005, which is a 22% increase from the third quarter 2004.
Iridium and other satellite phones may be identifiable to the listener because of the particular "clipping" effect of the data compression and the latency (experienced as a noticeable lag or time delay) due to the electronic equipment used.
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