{"id":279,"date":"2012-05-23T11:01:09","date_gmt":"2012-05-23T11:01:09","guid":{"rendered":"http:\/\/www.chemicool.com\/elements\/?page_id=279"},"modified":"2017-12-07T02:07:39","modified_gmt":"2017-12-07T07:07:39","slug":"chromium","status":"publish","type":"page","link":"https:\/\/www.chemicool.com\/elements\/chromium.html","title":{"rendered":"Chromium 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\">24<\/div>\n<div class=\"clearT\"><\/div>\n<div class=\"elnamT\">Cr<\/div>\n<div class=\"atweiT\"> 52.00<\/div>\n<\/div>\n<p>The chemical element chromium is classed as a transition metal. It was discovered in 1780 by Nicolas Louis Vauquelin.<\/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<h2 class=\"heading\">Data Zone<\/h2>\n<table class=\"datatop\">\n<tr>\n<td class=\"elemglb\">Classification:<\/td>\n<td> Chromium is a transition metal  <\/td>\n<\/tr>\n<tr>\n<td class=\"elemglb\">Color:<\/td>\n<td>  silver-gray  <\/td>\n<\/tr>\n<tr>\n<td class=\"elemglb\">Atomic weight:<\/td>\n<td> 51.996 <\/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> 1907 <sup>o<\/sup>C, 2180 K    <\/td>\n<\/tr>\n<tr>\n<td class=\"elemglb\">Boiling point:<\/td>\n<td>   2670 <sup>o<\/sup>C, 2943 K     <\/td>\n<\/tr>\n<tr>\n<td class=\"elemglb\">Electrons:<\/td>\n<td>24<\/td>\n<\/tr>\n<tr>\n<td class=\"elemglb\">Protons:<\/td>\n<td>24<\/td>\n<\/tr>\n<tr>\n<td class=\"elemglb\">Neutrons in most abundant isotope:<\/td>\n<td>28<\/td>\n<\/tr>\n<tr>\n<td class=\"elemglb\">Electron shells:<\/td>\n<td>   2,8,13,1    <\/td>\n<\/tr>\n<tr>\n<td class=\"elemglb\">Electron configuration:<\/td>\n<td>   [Ar] 3d<sup>5<\/sup> 4s<sup>1<\/sup>    <\/td>\n<\/tr>\n<tr>\n<td class=\"elemglb\">Density @ 20<sup>o<\/sup>C:<\/td>\n<td>  7.19  g\/cm<sup>3<\/sup>  <\/td>\n<\/tr>\n<\/table>\n<span class=\"collapseomatic \" id=\"id6a3201aa29004\"  tabindex=\"0\" title=\"Show more, including: Heats, Energies, Oxidation, Reactions,&lt;br \/&gt; Compounds, Radii, Conductivities\"    >Show more, including: Heats, Energies, Oxidation, Reactions,<br \/> Compounds, Radii, Conductivities<\/span><div id=\"target-id6a3201aa29004\" class=\"collapseomatic_content \">\n<table class=\"datatop\">\n<tr>\n<td class=\"elemglb\">Atomic volume:<\/td>\n<td>   7.23 cm<sup>3<\/sup>\/mol  <\/td>\n<\/tr>\n<tr>\n<td class=\"elemglb\">Structure:<\/td>\n<td>    bcc: body-centered cubic  <\/td>\n<\/tr>\n<tr>\n<td class=\"elemglb\">Hardness: <\/td>\n<td>    8.5  mohs <\/td>\n<\/tr>\n<tr>\n<td class=\"elemglb\">Specific heat capacity<\/td>\n<td>  0.45   J g<sup>-1<\/sup> K<sup>-1<\/sup>  <\/td>\n<\/tr>\n<tr>\n<td class=\"elemglb\">Heat of fusion<\/td>\n<td>  21.0 kJ mol<sup>-1<\/sup>  <\/td>\n<\/tr>\n<tr>\n<td class=\"elemglb\">Heat of atomization<\/td>\n<td>  397    kJ mol<sup>-1<\/sup> <\/td>\n<\/tr>\n<tr>\n<td class=\"elemglb\">Heat of vaporization<\/td>\n<td>  339.5  kJ mol<sup>-1<\/sup>    <\/td>\n<\/tr>\n<tr>\n<td class=\"elemglb\">1<sup>st<\/sup> ionization energy<\/td>\n<td>  652.8  kJ mol<sup>-1<\/sup>    <\/td>\n<\/tr>\n<tr>\n<td class=\"elemglb\">2<sup>nd<\/sup> ionization energy<\/td>\n<td>  1592  kJ mol<sup>-1<\/sup>    <\/td>\n<\/tr>\n<tr>\n<td class=\"elemglb\">3<sup>rd<\/sup> ionization energy<\/td>\n<td>    2987.2 kJ mol<sup>-1<\/sup>   <\/td>\n<\/tr>\n<tr>\n<td class=\"elemglb\">Electron affinity<\/td>\n<td>   64.3  kJ mol<sup>-1<\/sup>  <\/td>\n<\/tr>\n<tr>\n<td class=\"elemglb\">Minimum oxidation number<\/td>\n<td>  -2    <\/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> 1.66  <\/td>\n<\/tr>\n<tr>\n<td class=\"elemglb\"> Polarizability volume <\/td>\n<td>    11.6 &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>  passivated  <\/td>\n<\/tr>\n<tr>\n<td class=\"elemglb\"> Reaction with 6 M HCl <\/td>\n<td>   mild, &#8658; H<sub>2<\/sub>, CrCl<sub>3<\/sub> <\/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>  CrO<sub>2<\/sub>, CrO<sub>3<\/sub>, Cr<sub>2<\/sub>O<sub>3<\/sub> (chromia) + non-stoich  <\/td>\n<\/tr>\n<tr>\n<td class=\"elemglb\"> Hydride(s) <\/td>\n<td>  CrH <\/td>\n<\/tr>\n<tr>\n<td class=\"elemglb\"> Chloride(s) <\/td>\n<td>  CrCl<sub>2<\/sub>, CrCl<sub>3<\/sub> <\/td>\n<\/tr>\n<tr>\n<td class=\"elemglb\">Atomic radius <\/td>\n<td>   140 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>   90.5  pm <\/td>\n<\/tr>\n<tr>\n<td class=\"elemglb\">Ionic radius (3+ ion) <\/td>\n<td> 75.5  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>  93.9  W m<sup>-1<\/sup> K<sup>-1<\/sup> <\/td>\n<\/tr>\n<tr>\n<td class=\"elemglb\"> Electrical conductivity <\/td>\n<td>  7.9 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> 1907 <sup>o<\/sup>C, 2180 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:\/\/chemicool.com\/elements\/images\/300-chromium.jpg\" width=\"300\" height=\"161\" alt=\"Chromium.\" class=\"size-full\" \/><p class=\"wp-caption-text\">Chromium. Photo by Tomihahndorf.<\/p><\/div>\n<\/div>\n<\/div>\n<p><a id=\"discovery\"><\/a><\/p>\n<h2>Discovery of Chromium<\/h2>\n<div class=\"author\">Dr. Doug Stewart<\/div>\n<p>    Chromium was discovered in 1780 by French chemist Nicolas Louis Vauquelin in Paris. He discovered the element in a mineral sample of &#8216;Siberian red lead&#8217;- now known as crocoite (lead chromate).<\/p>\n<p>He boiled the crushed mineral with potassium carbonate to produce lead carbonate and a yellow potassium salt solution of chromic acid. <\/p>\n<p>Vauquelin was convinced by further experiments on the solution that he had found a new metal.<\/p>\n<p>In 1781 he succeeded in isolating the metal. Initially he removed the lead from the mineral sample by precipitation with hydrochloric acid. Vauquelin then obtained the oxide by evaporation and finally isolated chromium by heating the oxide in a charcoal oven. <sup>(1),(2)<\/sup>.<\/p>\n<p>Vauquelin also identified small amounts of chromium in ruby and emerald stones.<\/p>\n<p>Vauquelin went on to discover <a href=\"https:\/\/www.chemicool.com\/elements\/beryllium.html\">Beryllium<\/a> in 1798.<\/p>\n<p>Chromium was named from the Greek word &#8216;chroma&#8217;, meaning color because it forms a variety of colorful compounds.<\/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<p><iframe loading=\"lazy\" width=\"300\" height=\"233\" src=\"https:\/\/www.youtube.com\/embed\/SbXC3qAB6F8\" allowfullscreen><\/iframe><\/p>\n<div class=\"youtubecaption\">Transition metals are well-known for their multiple colored ions. Here&#8217;s an entertaining color change from Cr +6 (orange) to Cr +3 (green). Ammonium dichromate burns and forms chromium (III) oxide.<\/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 \tChromium metal is an essential trace element, but hexavalent chromium Cr(VI) is very toxic and carcinogenic.<\/p>\n<p>\t  <strong>Characteristics:<\/strong><\/p>\n<p>\t\t Chromium is a silver, lustrous, very hard metal that can take a high mirror polish. It is also odorless, tasteless, and malleable.<\/p>\n<p>\t\tThe metal forms a thin protective oxide coating in air. It burns when heated to form green chromium oxide Cr<sub>2<\/sub>O<sub>3<\/sub>. <\/p>\n<p><a id=\"uses\"><\/a><\/p>\n<h2>Uses of Chromium<\/h2>\n<p>\t\tChromium is used in stainless steel, and other alloys. Chromium plating, for example on cars and bicycles, produces a smooth, silver finish that is highly resistant to corrosion. <\/p>\n<p>\t\tThe metal is also widely used as a catalyst.<\/p>\n<p>\t\tChromium compounds are valued as pigments for their vivid green, yellow, red and orange colors.<\/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>  102 parts per million by weight, 40 parts per million by moles<\/p>\n<p>\t\t<span class=\"elemgl\">Abundance solar system:<\/span> 20 parts per million by weight,  0.4 parts per million by moles<\/p>\n<p>\t\t\t\t<span class=\"elemgl\">Cost, pure:<\/span>   $32 per 100g<\/p>\n<p>\t\t\t\t<span class=\"elemgl\">Cost, bulk:<\/span>  $0.28 per 100g<\/p>\n<p>\t\t<span class=\"elemgl\">Source:<\/span> Chromium is not found as a free element in nature but is found in the form of ores. The main ore of chromium is chromite FeCr<sub>2<\/sub>O<sub>4<\/sub>.<\/p>\n<p>\t\tTo isolate the metal commercially, chromite ore is oxidized to chromium(III) oxide (Cr<sub>2<\/sub>O<sub>3<\/sub>). The metal is then obtained by heating the oxide in the presence of aluminum or silicon.<\/p>\n<p>\t\t<span class=\"elemgl\">Isotopes:<\/span> Chromium has 21 isotopes whose half-lives are known, with mass numbers 42 to 63. Naturally occurring chromium  is a mixture of four isotopes and they are found in the percentages shown: <sup>50<\/sup>Cr (4.3%), <sup>52<\/sup>Cr (83.8%), <sup>53<\/sup>Cr (9.5%) and <sup>54<\/sup>Cr (2.4%). <\/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>Mary Elvira Weeks, Discovery of the Elements V., Journal of Chemical Education, March 1932 p 470. <\/li>\n<li>Per Enghag, Encyclopedia of the elements: technical data, history, processing, applications.,p 577- 578, John Wiley and Sons, 2004<\/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\/chromium.html\"&gt;Chromium&lt;\/a&gt;\r\n<\/pre>\n<p>or<\/p>\n<pre class='code'>\r\n&lt;a href=\"https:\/\/www.chemicool.com\/elements\/chromium.html\"&gt;Chromium 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\"Chromium.\" Chemicool Periodic Table. Chemicool.com. 16 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\/chromium.html&gt;.<\/pre>\n","protected":false},"excerpt":{"rendered":"<p>Data Zone | Discovery | Facts | Appearance &amp; Characteristics | Uses | Abundance &amp; Isotopes | References 24 Cr 52.00 The chemical element chromium is classed as a transition metal. It was discovered in 1780 by Nicolas Louis Vauquelin. Data Zone Data Zone Classification: Chromium is a transition metal Color: silver-gray Atomic weight: 51.996 [&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-279","1":"page","2":"type-page","3":"status-publish","5":"entry"},"_links":{"self":[{"href":"https:\/\/www.chemicool.com\/elements\/wp-json\/wp\/v2\/pages\/279","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=279"}],"version-history":[{"count":24,"href":"https:\/\/www.chemicool.com\/elements\/wp-json\/wp\/v2\/pages\/279\/revisions"}],"predecessor-version":[{"id":4448,"href":"https:\/\/www.chemicool.com\/elements\/wp-json\/wp\/v2\/pages\/279\/revisions\/4448"}],"wp:attachment":[{"href":"https:\/\/www.chemicool.com\/elements\/wp-json\/wp\/v2\/media?parent=279"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}