{"id":487,"date":"2012-05-27T21:49:52","date_gmt":"2012-05-27T21:49:52","guid":{"rendered":"http:\/\/www.chemicool.com\/elements\/?page_id=487"},"modified":"2017-12-07T02:08:08","modified_gmt":"2017-12-07T07:08:08","slug":"iridium","status":"publish","type":"page","link":"https:\/\/www.chemicool.com\/elements\/iridium.html","title":{"rendered":"Iridium Element Facts"},"content":{"rendered":"<div class=\"insidepagelinks\">\n<a href=\"#data\">Data Zone<\/a> |  <a href=\"#discovery\">Discovery<\/a> |  <a href=\"#facts\">Facts<\/a> | <a href=\"#appear\">Appearance &amp; Characteristics<\/a> | <a href=\"#uses\">Uses<\/a> | <a href=\"#abund\">Abundance &amp; Isotopes<\/a>  | <a href=\"#refer\">References<\/a>\n<\/div>\n<div class=\"tmetalsT\">\n<div class=\"atnorT\">77<\/div>\n<div class=\"clearT\"><\/div>\n<div class=\"elnamT\">Ir<\/div>\n<div class=\"atweiT\"> 192.2<\/div>\n<\/div>\n<p>The chemical element iridium  is classed as a transition metal. It was discovered in 1803 by Smithson Tennant.<\/p>\n<div style=\"clear:both;\"><\/div>\n<div class=\"adsense300\">\n<div class=\"adsense300spacer\">\n<div style=\"line-height:10px;\"><img decoding=\"async\" src=\"\/\/www.chemicool.com\/ad.png\" alt=\"\" \/><\/div>\n<p><script async src=\"\/\/pagead2.googlesyndication.com\/pagead\/js\/adsbygoogle.js\"><\/script><ins class=\"adsbygoogle\" style=\"display: block;\" data-ad-client=\"ca-pub-9461632227417539\" data-ad-slot=\"8753977201\" data-ad-format=\"auto\"><\/ins><script>(adsbygoogle = window.adsbygoogle || []).push({});<\/script><\/p>\n<p><a id=\"data\"><\/a><\/p>\n<h2>Data Zone<\/h2>\n<table class=\"datatop\">\n<tr>\n<td class=\"elemglb\">Classification:<\/td>\n<td>  Iridium is a transition metal   <\/td>\n<\/tr>\n<tr>\n<td class=\"elemglb\">Color:<\/td>\n<td>  silvery-white  <\/td>\n<\/tr>\n<tr>\n<td class=\"elemglb\">Atomic weight:<\/td>\n<td>   192.22 <\/td>\n<\/tr>\n<tr>\n<td class=\"elemglb\">State:<\/td>\n<td>    solid  <\/td>\n<\/tr>\n<tr>\n<td class=\"elemglb\">Melting point:<\/td>\n<td> 2447 <sup>o<\/sup>C, 2720  K    <\/td>\n<\/tr>\n<tr>\n<td class=\"elemglb\">Boiling point:<\/td>\n<td>  4430 <sup>o<\/sup>C, 4703  K     <\/td>\n<\/tr>\n<tr>\n<td class=\"elemglb\">Electrons:<\/td>\n<td>77<\/td>\n<\/tr>\n<tr>\n<td class=\"elemglb\">Protons:<\/td>\n<td>77<\/td>\n<\/tr>\n<tr>\n<td class=\"elemglb\">Neutrons in most abundant isotope:<\/td>\n<td>116<\/td>\n<\/tr>\n<tr>\n<td class=\"elemglb\">Electron shells:<\/td>\n<td>    2,8,18,32,15,2     <\/td>\n<\/tr>\n<tr>\n<td class=\"elemglb\">Electron configuration:<\/td>\n<td>   [Xe] 4f<sup>14<\/sup> 5d<sup>7<\/sup> 6s<sup>2<\/sup>    <\/td>\n<\/tr>\n<tr>\n<td class=\"elemglb\">Density @ 20<sup>o<\/sup>C:<\/td>\n<td>  22.56  g\/cm<sup>3<\/sup>   <\/td>\n<\/tr>\n<\/table>\n<span class=\"collapseomatic \" id=\"id6a3a62b15fbba\"  tabindex=\"0\" title=\"Show more, including: Heats, Energies, Oxidation,&lt;br \/&gt; Reactions, Compounds, Radii, Conductivities\"    >Show more, including: Heats, Energies, Oxidation,<br \/> Reactions, Compounds, Radii, Conductivities<\/span><div id=\"target-id6a3a62b15fbba\" class=\"collapseomatic_content \">\n<table class=\"datatop\">\n<tr>\n<td class=\"elemglb\">Atomic volume:<\/td>\n<td>   8.54 cm<sup>3<\/sup>\/mol   <\/td>\n<\/tr>\n<tr>\n<td class=\"elemglb\">Structure:<\/td>\n<td>   fcc: face-centered cubic <\/td>\n<\/tr>\n<tr>\n<td class=\"elemglb\">Hardness: <\/td>\n<td>    6.5  mohs  <\/td>\n<\/tr>\n<tr>\n<td class=\"elemglb\">Specific heat capacity<\/td>\n<td>  0.13   J g<sup>-1<\/sup> K<sup>-1<\/sup>  <\/td>\n<\/tr>\n<tr>\n<td class=\"elemglb\">Heat of fusion<\/td>\n<td>  26.10 kJ mol<sup>-1<\/sup>  <\/td>\n<\/tr>\n<tr>\n<td class=\"elemglb\">Heat of atomization<\/td>\n<td>  671    kJ mol<sup>-1<\/sup> <\/td>\n<\/tr>\n<tr>\n<td class=\"elemglb\">Heat of vaporization<\/td>\n<td>   563  kJ mol<sup>-1<\/sup>   <\/td>\n<\/tr>\n<tr>\n<td class=\"elemglb\">1<sup>st<\/sup> ionization energy<\/td>\n<td>    880  kJ mol<sup>-1<\/sup>   <\/td>\n<\/tr>\n<tr>\n<td class=\"elemglb\">2<sup>nd<\/sup> ionization energy<\/td>\n<td>   1600  kJ mol<sup>-1<\/sup>    <\/td>\n<\/tr>\n<tr>\n<td class=\"elemglb\">3<sup>rd<\/sup> ionization energy<\/td>\n<td>  &#8211;   <\/td>\n<\/tr>\n<tr>\n<td class=\"elemglb\">Electron affinity<\/td>\n<td>   151  kJ mol<sup>-1<\/sup>  <\/td>\n<\/tr>\n<tr>\n<td class=\"elemglb\">Minimum oxidation number<\/td>\n<td>  -1    <\/td>\n<\/tr>\n<tr>\n<td class=\"elemglb\">Min. common oxidation no.<\/td>\n<td>  -1   <\/td>\n<\/tr>\n<tr>\n<td class=\"elemglb\"> Maximum oxidation number <\/td>\n<td> 6 <\/td>\n<\/tr>\n<tr>\n<td class=\"elemglb\"> Max. common oxidation no. <\/td>\n<td>  4  <\/td>\n<\/tr>\n<tr>\n<td class=\"elemglb\"> Electronegativity (Pauling Scale) <\/td>\n<td> 2.2  <\/td>\n<\/tr>\n<tr>\n<td class=\"elemglb\"> Polarizability volume <\/td>\n<td>   7.6 &Aring;<sup>3<\/sup>  <\/td>\n<\/tr>\n<tr>\n<td class=\"elemglb\"> Reaction with air<\/td>\n<td> none   <\/td>\n<\/tr>\n<tr>\n<td class=\"elemglb\"> Reaction with 15 M HNO<sub>3<\/sub> <\/td>\n<td>  none  <\/td>\n<\/tr>\n<tr>\n<td class=\"elemglb\"> Reaction with 6 M HCl <\/td>\n<td> none  <\/td>\n<\/tr>\n<tr>\n<td class=\"elemglb\"> Reaction with 6 M NaOH <\/td>\n<td>   none  <\/td>\n<\/tr>\n<tr>\n<td class=\"elemglb\"> Oxide(s) <\/td>\n<td>   IrO<sub>2<\/sub>, Ir<sub>2<\/sub>O<sub>3<\/sub>  <\/td>\n<\/tr>\n<tr>\n<td class=\"elemglb\"> Hydride(s) <\/td>\n<td>   &#8211;  <\/td>\n<\/tr>\n<tr>\n<td class=\"elemglb\"> Chloride(s) <\/td>\n<td>   IrCl<sub>2<\/sub>, IrCl<sub>3<\/sub>, IrCl<sub>4<\/sub> <\/td>\n<\/tr>\n<tr>\n<td class=\"elemglb\">Atomic radius <\/td>\n<td>   136 pm  <\/td>\n<\/tr>\n<tr>\n<td class=\"elemglb\">Ionic radius (1+ ion) <\/td>\n<td> &#8211; <\/td>\n<\/tr>\n<tr>\n<td class=\"elemglb\">Ionic radius (2+ ion) <\/td>\n<td>   &#8211;  <\/td>\n<\/tr>\n<tr>\n<td class=\"elemglb\">Ionic radius (3+ ion) <\/td>\n<td> 82  pm <\/td>\n<\/tr>\n<tr>\n<td class=\"elemglb\"> Ionic radius (1- ion) <\/td>\n<td>   &#8211;  <\/td>\n<\/tr>\n<tr>\n<td class=\"elemglb\"> Ionic radius (2- ion) <\/td>\n<td> &#8211; <\/td>\n<\/tr>\n<tr>\n<td class=\"elemglb\"> Ionic radius (3- ion) <\/td>\n<td>   &#8211;  <\/td>\n<\/tr>\n<tr>\n<td class=\"elemglb\"> Thermal conductivity <\/td>\n<td> 147  W m<sup>-1<\/sup> K<sup>-1<\/sup> <\/td>\n<\/tr>\n<tr>\n<td class=\"elemglb\"> Electrical conductivity <\/td>\n<td>  21.3 x 10<sup>6<\/sup> S m<sup>-1<\/sup>  <\/td>\n<\/tr>\n<tr>\n<td class=\"elemglb\">Freezing\/Melting point:<\/td>\n<td> 2447 <sup>o<\/sup>C, 2720  K    <\/td>\n<\/tr>\n<\/table>\n<\/div>\n<\/div>\n<div class=\"leftimagepadding\">\n<\/div>\n<\/div>\n<p><a id=\"discovery\"><\/a><\/p>\n<h2>Discovery of Iridium<\/h2>\n<div class=\"author\">Dr. Doug Stewart<\/div>\n<p>   Iridium was discovered in 1803, by English chemist Smithson Tennant in London.<\/p>\n<p>\t\tHe found it in the residue left when crude <a href=\"https:\/\/www.chemicool.com\/elements\/platinum.html\">platinum<\/a> had been dissolved in aqua regia (a mixture of hydrochloric acid and nitric acid).<\/p>\n<p>\t\tSmithson Tennant also discovered <a href=\"https:\/\/www.chemicool.com\/elements\/osmium.html\">osmium<\/a> at the same time.<\/p>\n<p>\t\tIridium&#8217;s name comes from the Latin word &#8216;iris&#8217;, meaning rainbow, because many of its salts are highly colored.<\/p>\n<p>\t\tAbnormally high amounts of iridium have been found in rocks dating to the K-T boundary between the Cretaceous and Tertiary periods (65 million years ago).<\/p>\n<p>\t\tThis has led to a widely held view that an iridium-containing comet struck the Earth at that time, leading to the extinction of the dinosaurs and many other forms of life.<\/p>\n<p>\t  The photo below shows the iridium rich layer, which marks the demise of the dinosaurs. Image Ref. <sup>(1)<\/sup>.<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/chemicool.com\/elements\/images\/300-iridium-layer.jpg\" width=\"300\" height=\"158\" alt=\"Iridium rich layer\" class=\"aligncenter size-full\" \/><\/p>\n<div style=\"clear:both;line-height:20px;\">&nbsp;<\/div>\n<div class=\"adsense300\">\n<div class=\"adsense300spacer\">\n<div style=\"line-height: 10px;\"><img decoding=\"async\" src=\"\/\/www.chemicool.com\/ad.png\" alt=\"\" \/><\/div>\n<p><script async src=\"\/\/pagead2.googlesyndication.com\/pagead\/js\/adsbygoogle.js\"><\/script><ins class=\"adsbygoogle\" style=\"display: inline-block; width: 336px; height: 280px;\" data-ad-client=\"ca-pub-9461632227417539\" data-ad-slot=\"2986645201\"><\/ins><script>(adsbygoogle = window.adsbygoogle || []).push({});<\/script><\/p>\n<div class=\"leftimagepadding\">\n<div style=\"width: 310px\" class=\"wp-caption alignnone\"><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/www.chemicool.com\/elements\/images\/300-iridium-metal.jpg\" width=\"300\" height=\"229\" alt=\"Iridium\" class=\"size-full\" \/><p class=\"wp-caption-text\">Iridium metal. Photo by Dschwen.<\/p><\/div>\n<\/div>\n<\/div>\n<\/div>\n<p><a id=\"appear\"><\/a><\/p>\n<h3>Appearance and Characteristics<\/h3>\n<p>  <strong>Harmful effects:<\/strong> <\/p>\n<p>\t \tIridium is considered to be of low toxicity.<\/p>\n<p>\t\tIridium in powder form is a known irritant and is a fire hazard.<\/p>\n<p>\t  <strong>Characteristics:<\/strong><\/p>\n<p>\t\tIridium is a rare, hard, lustrous, brittle, very dense platinum-like metal.<\/p>\n<p>\t\tChemically it is very unreactive.<\/p>\n<p>\t\tIt is the most corrosion-resistant metal known and it resists attack by any acid.<\/p>\n<p>\t\tIridium is attacked by molten salts such as sodium chloride (NaCl) and sodium cyanide (NaCN).<\/p>\n<p>\t\tIridium is generally credited with being the second densest element (after <a href=\"https:\/\/www.chemicool.com\/elements\/osmium.html\">osmium<\/a>) based on measured density, although calculations involving the space lattices of the elements show that iridium is denser.<\/p>\n<p><a id=\"uses\"><\/a><\/p>\n<h2>Uses of Iridium<\/h2>\n<p>\t\tThe main use of iridium is as a hardening agent for platinum alloys.<\/p>\n<p>\t\tWith osmium, it forms an alloy that is used for tipping pens, and compass bearings.<\/p>\n<p>\t\tIridium is used in making crucibles and other equipment that is used at high temperatures.<\/p>\n<p>\t\tIt is also used to make heavy-duty electrical contacts.<\/p>\n<p>\t\tIridium was used in making the international standard kilogram, which is an alloy of 90% platinum and 10% iridium.<\/p>\n<p>\t\tRadioactive isotopes of iridium are used in radiation therapy for the treatment of cancer.  <\/p>\n<p><a id=\"abund\"><\/a><\/p>\n<h2>Abundance and Isotopes<\/h2>\n<p><span class=\"elemgl\">Abundance earth&#8217;s crust:<\/span>  0.4 parts per billion by weight,  0.05 parts per billion by moles<\/p>\n<p>\t\t<span class=\"elemgl\">Abundance solar system:<\/span> 2 parts per billion by weight, 0.01 parts per billion by moles<\/p>\n<p>\t\t\t\t<span class=\"elemgl\">Cost, pure:<\/span>   $4200 per 100g<\/p>\n<p>\t\t\t\t<span class=\"elemgl\">Cost, bulk:<\/span>  $2300  per 100g<\/p>\n<p>\t\t<span class=\"elemgl\">Source:<\/span> Iridium is found in natural alloys with platinum and osmium in alluvial deposits. Commercially, iridium is recovered as a by-product from the <a href=\"https:\/\/www.chemicool.com\/elements\/nickel.html\">nickel<\/a> mining industry.  <\/p>\n<p>\t\t<span class=\"elemgl\">Isotopes:<\/span> Iridium has 34 isotopes whose half-lives are known, with mass numbers from 165 to 198. Naturally occurring iridium is a mixture of two isotopes: <sup>191<\/sup>Ir and <sup>193<\/sup>Ir with natural abundances of 37.3% and 62.7% respectively. <\/p>\n<div style=\"max-width: 750px;\">\n<div style=\"line-height: 10px;\"><img decoding=\"async\" src=\"\/\/www.chemicool.com\/ad.png\" alt=\"\" \/><\/div>\n<p><script async src=\"\/\/pagead2.googlesyndication.com\/pagead\/js\/adsbygoogle.js\"><\/script><ins class=\"adsbygoogle\" style=\"display: block;\" data-ad-client=\"ca-pub-9461632227417539\" data-ad-slot=\"8753977201\" data-ad-format=\"auto\"><\/ins><script>(adsbygoogle = window.adsbygoogle || []).push({});<\/script><\/p>\n<\/div>\n<p><a id=\"refer\"><\/a><\/p>\n<h4>References<\/h4>\n<ol>\n<li><a href=\"http:\/\/esp.cr.usgs.gov\/info\/kt\/stop2b.html\">U.S. Geological Survey<\/a><\/li>\n<\/ol>\n<h4>Cite this Page<\/h4>\n<p>For online linking, please copy and paste one of the following:<\/p>\n<pre class='code'>\r\n&lt;a href=\"https:\/\/www.chemicool.com\/elements\/iridium.html\"&gt;Iridium&lt;\/a&gt;\r\n<\/pre>\n<p>or<\/p>\n<pre class='code'>\r\n&lt;a href=\"https:\/\/www.chemicool.com\/elements\/iridium.html\"&gt;Iridium Element Facts&lt;\/a&gt;\r\n<\/pre>\n<p>To cite this page in an academic document, please use the following MLA compliant citation:<\/p>\n<pre class='code'>\r\n\"Iridium.\" Chemicool Periodic Table. Chemicool.com. 17 Oct. 2012. Web. <script type=\"text\/javascript\">\r\n<!--\r\nvar currentTime = new Date()\r\nvar month = currentTime.getMonth() + 1\r\nvar day = currentTime.getDate()\r\nvar year = currentTime.getFullYear()\r\ndocument.write(month + \"\/\" + day + \"\/\" + year)\r\n\/\/-->\r\n<\/script> \r\n&lt;https:\/\/www.chemicool.com\/elements\/iridium.html&gt;.<\/pre>\n","protected":false},"excerpt":{"rendered":"<p>Data Zone | Discovery | Facts | Appearance &amp; Characteristics | Uses | Abundance &amp; Isotopes | References 77 Ir 192.2 The chemical element iridium is classed as a transition metal. It was discovered in 1803 by Smithson Tennant. Data Zone Classification: Iridium is a transition metal Color: silvery-white Atomic weight: 192.22 State: solid Melting [&hellip;]<\/p>\n","protected":false},"author":3,"featured_media":0,"parent":0,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"_genesis_hide_title":false,"_genesis_hide_breadcrumbs":false,"_genesis_hide_singular_image":false,"_genesis_hide_footer_widgets":false,"_genesis_custom_body_class":"","_genesis_custom_post_class":"","_genesis_layout":"","footnotes":""},"class_list":{"0":"post-487","1":"page","2":"type-page","3":"status-publish","5":"entry"},"_links":{"self":[{"href":"https:\/\/www.chemicool.com\/elements\/wp-json\/wp\/v2\/pages\/487","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.chemicool.com\/elements\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/www.chemicool.com\/elements\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/www.chemicool.com\/elements\/wp-json\/wp\/v2\/users\/3"}],"replies":[{"embeddable":true,"href":"https:\/\/www.chemicool.com\/elements\/wp-json\/wp\/v2\/comments?post=487"}],"version-history":[{"count":20,"href":"https:\/\/www.chemicool.com\/elements\/wp-json\/wp\/v2\/pages\/487\/revisions"}],"predecessor-version":[{"id":4251,"href":"https:\/\/www.chemicool.com\/elements\/wp-json\/wp\/v2\/pages\/487\/revisions\/4251"}],"wp:attachment":[{"href":"https:\/\/www.chemicool.com\/elements\/wp-json\/wp\/v2\/media?parent=487"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}