{"id":383,"date":"2012-05-24T21:30:17","date_gmt":"2012-05-24T21:30:17","guid":{"rendered":"http:\/\/www.chemicool.com\/elements\/?page_id=383"},"modified":"2017-12-07T02:08:38","modified_gmt":"2017-12-07T07:08:38","slug":"rhodium","status":"publish","type":"page","link":"https:\/\/www.chemicool.com\/elements\/rhodium.html","title":{"rendered":"Rhodium 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\">45<\/div>\n<div class=\"clearT\"><\/div>\n<div class=\"elnamT\">Rh<\/div>\n<div class=\"atweiT\">102.9<\/div>\n<\/div>\n<p>The chemical element rhodium is classed as a transition metal. It was discovered in 1803 by William H. Wollaston.<\/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> Rhodium 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>   102.9055 <\/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>  1963 <sup>o<\/sup>C, 2236 K    <\/td>\n<\/tr>\n<tr>\n<td class=\"elemglb\">Boiling point:<\/td>\n<td>   3695 <sup>o<\/sup>C, 3968 K    <\/td>\n<\/tr>\n<tr>\n<td class=\"elemglb\">Electrons:<\/td>\n<td>45<\/td>\n<\/tr>\n<tr>\n<td class=\"elemglb\">Protons:<\/td>\n<td>45<\/td>\n<\/tr>\n<tr>\n<td class=\"elemglb\">Neutrons in most abundant isotope:<\/td>\n<td>58<\/td>\n<\/tr>\n<tr>\n<td class=\"elemglb\">Electron shells:<\/td>\n<td>    2,8,18,16,1     <\/td>\n<\/tr>\n<tr>\n<td class=\"elemglb\">Electron configuration:<\/td>\n<td>   [Kr]  4d<sup>8<\/sup> 5s<sup>1<\/sup>   <\/td>\n<\/tr>\n<tr>\n<td class=\"elemglb\">Density @ 20<sup>o<\/sup>C:<\/td>\n<td>  12.4 g\/cm<sup>3<\/sup>   <\/td>\n<\/tr>\n<\/table>\n<span class=\"collapseomatic \" id=\"id6a44d8575ad05\"  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-id6a44d8575ad05\" class=\"collapseomatic_content \">\n<table class=\"datatop\">\n<tr>\n<td class=\"elemglb\">Atomic volume:<\/td>\n<td>   8.3 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>   6.0  mohs  <\/td>\n<\/tr>\n<tr>\n<td class=\"elemglb\">Specific heat capacity<\/td>\n<td>   0.242   J g<sup>-1<\/sup> K<sup>-1<\/sup>  <\/td>\n<\/tr>\n<tr>\n<td class=\"elemglb\">Heat of fusion<\/td>\n<td> 21.50 kJ mol<sup>-1<\/sup>  <\/td>\n<\/tr>\n<tr>\n<td class=\"elemglb\">Heat of atomization<\/td>\n<td>  556  kJ mol<sup>-1<\/sup> <\/td>\n<\/tr>\n<tr>\n<td class=\"elemglb\">Heat of vaporization<\/td>\n<td>  493.0 kJ mol<sup>-1<\/sup>   <\/td>\n<\/tr>\n<tr>\n<td class=\"elemglb\">1<sup>st<\/sup> ionization energy<\/td>\n<td>  719.8  kJ mol<sup>-1<\/sup>   <\/td>\n<\/tr>\n<tr>\n<td class=\"elemglb\">2<sup>nd<\/sup> ionization energy<\/td>\n<td>  1744.4  kJ mol<sup>-1<\/sup>   <\/td>\n<\/tr>\n<tr>\n<td class=\"elemglb\">3<sup>rd<\/sup> ionization energy<\/td>\n<td>   2996.8 kJ mol<sup>-1<\/sup>   <\/td>\n<\/tr>\n<tr>\n<td class=\"elemglb\">Electron affinity<\/td>\n<td>    109.7  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> 0   <\/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>  3  <\/td>\n<\/tr>\n<tr>\n<td class=\"elemglb\"> Electronegativity (Pauling Scale) <\/td>\n<td> 2.28  <\/td>\n<\/tr>\n<tr>\n<td class=\"elemglb\"> Polarizability volume <\/td>\n<td>   8.6 &Aring;<sup>3<\/sup> <\/td>\n<\/tr>\n<tr>\n<td class=\"elemglb\"> Reaction with air<\/td>\n<td> mild, w\/ht, &#8658;  Rh<sub>2<\/sub>O<sub>3<\/sub>  <\/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>   &#8211;  <\/td>\n<\/tr>\n<tr>\n<td class=\"elemglb\"> Oxide(s) <\/td>\n<td>  RhO<sub>2<\/sub>, Rh<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>  RhCl<sub>3<\/sub> <\/td>\n<\/tr>\n<tr>\n<td class=\"elemglb\">Atomic radius <\/td>\n<td>   134 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> 80.5  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> 150  W m<sup>-1<\/sup> K<sup>-1<\/sup> <\/td>\n<\/tr>\n<tr>\n<td class=\"elemglb\"> Electrical conductivity <\/td>\n<td>  23 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>  1963 <sup>o<\/sup>C, 2236 K    <\/td>\n<\/tr>\n<\/table>\n<\/div>\n<\/div>\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-rhodium.jpg\" width=\"300\" height=\"160\" alt=\"Rhodium pin and foil.\" class=\"size-full\" \/><p class=\"wp-caption-text\">Rhodium pin and foil. Photo by Dschwen.<\/p><\/div>\n<\/div>\n<\/div>\n<p><a id=\"discovery\"><\/a><\/p>\n<h2>Discovery of Rhodium<\/h2>\n<div class=\"author\">Dr. Doug Stewart<\/div>\n<p>Rhodium was discovered in 1803, in London, by English chemist William H. Wollaston, when examining a platinum ore from Peru. <sup>(1)<\/sup> <\/p>\n<p>Wollaston was first alerted to the possibility of a new element by Hippolyte-Victor Collet-Descotils, who believed that the red color of some platinum salts was actually caused by the presence of an unidentified metal. <sup>(2)<\/sup><\/p>\n<p>To investigate this possibility, Wollaston first dissolved crude platinum in aqua regia, a concentrated solution of hydrochloric and nitric acids. He then precipitated platinum metal by dissolving the solution in ammonium chloride. <\/p>\n<p>The liquid which remained had properties which matched no known substance. <sup>(2)<\/sup> <\/p>\n<p>Wollaston conducted a series of chemical reactions on this liquid before producing a deep red powder, sodium rhodium chloride, RhCl<sub>6<\/sub>Na<sub>3<\/sub>.12H<sub>2<\/sub>O, which gave a black, flaky precipitate of rhodium when treated with zinc. <sup>(1)<\/sup> <\/p>\n<p>The element name comes from the Greek word &#8216;rhodon&#8217; meaning rose. Wollaston chose this name because of the rose color of a dilute solution of rhodium&#8217;s salts.<\/p>\n<p>1803 was a good year for William Wollaston. Not only did he discover rhodium, he also discovered another platinum group metal &#8211; palladium.<\/p>\n<p><strong>The Platinum Group Metals<\/strong><br \/>\nThese metals have similar properties and are often present in the same mineral ores.<\/p>\n<table class=\"navbar\">\n<tr>\n<td><a class=\"tmetals\" href=\"https:\/\/www.chemicool.com\/elements\/ruthenium.html\" title=\"ruthenium \"><sup>44<\/sup><br \/>Ru<\/a> <\/td>\n<td><a class=\"tmetals\" href=\"https:\/\/www.chemicool.com\/elements\/rhodium.html\" title=\"rhodium \"><sup>45<\/sup><br \/>Rh<\/a> <\/td>\n<td><a class=\"tmetals\" href=\"https:\/\/www.chemicool.com\/elements\/palladium.html\" title=\"palladium \"><sup>46<\/sup><br \/>Pd<\/a> <\/td>\n<\/tr>\n<tr>\n<td><a class=\"tmetals\" href=\"https:\/\/www.chemicool.com\/elements\/osmium.html\" title=\"osmium \"><sup>76<\/sup><br \/>Os<\/a> <\/td>\n<td><a class=\"tmetals\" href=\"https:\/\/www.chemicool.com\/elements\/iridium.html\" title=\"iridium \"><sup>77<\/sup><br \/>Ir<\/a> <\/td>\n<td><a class=\"tmetals\" href=\"https:\/\/www.chemicool.com\/elements\/platinum.html\" title=\"platinum \"><sup>78<\/sup><br \/>Pt<\/a> <\/td>\n<\/tr>\n<\/table>\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:\/\/chemicool.com\/elements\/images\/300-rhodium-catalyst.jpg\" width=\"300\" height=\"194\" alt=\"Rhodium catalyst for ethanol oxidation\" class=\"size-full\" \/><p class=\"wp-caption-text\">Catalyst for ethanol oxidation: platinum-rhodium clusters on a surface of tin dioxide. This catalyst can split the carbon-carbon bond and obtain energy from ethanol in fuel cells. Image by BNL. <sup>(3)<\/sup><\/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\t \tRhodium is considered to be non-toxic. Some of its compounds are highly toxic and carcinogenic.<\/p>\n<p>\t  <strong>Characteristics:<\/strong><\/p>\n<p>\t\t Rhodium is a rare, hard, silvery-white, lustrous metal.<\/p>\n<p>It is one of the of the six platinum group metals consisting of platinum, palladium, rhodium, osmium, iridium and ruthenium.<\/p>\n<p>\t\tIt is highly reflective and extremely resistant to corrosion.<\/p>\n<p>\t\tIt is not attacked by most acids.<\/p>\n<p>When present in compounds, rhodium exists mostly in the trivalent state, Rh<sup>3+<\/sup>.<\/p>\n<p>\t\tRhodium&#8217;s salts form rose-colored aqueous solutions.<\/p>\n<p><a id=\"uses\"><\/a><\/p>\n<h2>Uses of Rhodium<\/h2>\n<p>\t\tThe majority of rhodium is used as a catalyst in catalytic converters. It is also used to catalyze industrial processes.<\/p>\n<p>\t\tRhodium is used as an alloying agent for hardening and improving the corrosion resistance of <a href=\"https:\/\/www.chemicool.com\/elements\/platinum.html\">platinum<\/a> and <a href=\"https:\/\/www.chemicool.com\/elements\/palladium.html\">palladium<\/a>.<\/p>\n<p>\t\tAs a result of its low electrical resistance, low and stable contact resistance, and its stability against <a href=\"https:\/\/www.chemicool.com\/definition\/corrosion.html\">corrosion<\/a> rhodium is used as an electrical contact material.<\/p>\n<p>\t\tThe metal is used in jewelry and for decorations.  <\/p>\n<p><a id=\"abund\"><\/a><\/p>\n<h2>Abundance and and Isotopes<\/h2>\n<p>\t<span class=\"elemgl\">Abundance earth&#8217;s crust:<\/span> 1 part per billion by weight,   0.1 parts per billion by moles<\/p>\n<p>\t\t<span class=\"elemgl\">Abundance solar system:<\/span> 2 parts per billion by weight,  0.02 parts per billion by moles<\/p>\n<p>\t\t\t\t<span class=\"elemgl\">Cost, pure:<\/span>  $13,000 per 100g<\/p>\n<p>\t\t\t\t<span class=\"elemgl\">Cost, bulk:<\/span>     $7,000 per 100g<\/p>\n<p>\t\t<span class=\"elemgl\">Source:<\/span> Rhodium occurs in small quantities in ores metals such as <a href=\"https:\/\/www.chemicool.com\/elements\/platinum.html\">platinum<\/a>, <a href=\"https:\/\/www.chemicool.com\/elements\/palladium.html\">palladium<\/a>, <a href=\"https:\/\/www.chemicool.com\/elements\/nickel.html\">nickel<\/a>, <a href=\"https:\/\/www.chemicool.com\/elements\/silver.html\">silver<\/a>, and <a href=\"https:\/\/www.chemicool.com\/elements\/gold.html\">gold<\/a>. Commercially, it is obtained as a byproduct of refining nickel sulfide ores from Canada.<\/p>\n<p>\t\t<span class=\"elemgl\">Isotopes:<\/span> Rhodium has 24 isotopes whose half-lives are known, with mass numbers from 94 to 117. Naturally occurring rhodium consists of its one stable isotope, <sup>103<\/sup>Rh.<\/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>J.W. Mellor, A Comprehensive Treatise on Inorganic and Theoretical Chemistry Volume XV, 1936, Longmans, Green and Co., p545-546.<\/li>\n<li>William Nicolson, A Journal of Natural Philosophy, Chemistry and the Arts, Volumes 9-10, 1804, W. Stratford, p34-35. <\/li>\n<li>Photo: <a href=\"http:\/\/www.bnl.gov\/bnlweb\/pubaf\/pr\/PR_display.asp?prID=898\">BNL<\/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\/rhodium.html\"&gt;Rhodium&lt;\/a&gt;\r\n<\/pre>\n<p>or<\/p>\n<pre class='code'>\r\n&lt;a href=\"https:\/\/www.chemicool.com\/elements\/rhodium.html\"&gt;Rhodium 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\"Rhodium.\" Chemicool Periodic Table. Chemicool.com. 18 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\/rhodium.html&gt;.<\/pre>\n","protected":false},"excerpt":{"rendered":"<p>Data Zone | Discovery | Facts | Appearance &amp; Characteristics | Uses | Abundance &amp; Isotopes | References 45 Rh 102.9 The chemical element rhodium is classed as a transition metal. It was discovered in 1803 by William H. Wollaston. Data Zone Classification: Rhodium is a transition metal Color: silvery-white Atomic weight: 102.9055 State: solid [&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-383","1":"page","2":"type-page","3":"status-publish","5":"entry"},"_links":{"self":[{"href":"https:\/\/www.chemicool.com\/elements\/wp-json\/wp\/v2\/pages\/383","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=383"}],"version-history":[{"count":24,"href":"https:\/\/www.chemicool.com\/elements\/wp-json\/wp\/v2\/pages\/383\/revisions"}],"predecessor-version":[{"id":4292,"href":"https:\/\/www.chemicool.com\/elements\/wp-json\/wp\/v2\/pages\/383\/revisions\/4292"}],"wp:attachment":[{"href":"https:\/\/www.chemicool.com\/elements\/wp-json\/wp\/v2\/media?parent=383"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}