Atomic Weight of Iridium | Commission on Isotopic Abundances and Atomic Weights

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en"><head> <title>Atomic Weight of Iridium | Commission on Isotopic Abundances and Atomic Weights</title> <meta http-equiv="content-type" content="text/html; charset=UTF-8"> <link rel="stylesheet" type="text/css" media="all" href="stylesheet.css"><link rel="shortcut icon" href="favicon.ico" /> <link href="css/theme.blue.css" rel="stylesheet" type="text/css"/> <script type="text/javascript" src="js/jquery-1.11.1.min.js"></script> <script type="text/javascript" src="js/jquery.tablesorter.js"></script> <script type="text/javascript" src="js/jquery.tablesorter.min.js"></script> <script type="text/javascript" src="js/jquery.tablesorter.widgets.js"></script> <script> $(function() { $("#mytable").tablesorter({theme:'blue',sortList:[0,0],widgets:['zebra'],widthFixed:true}); $(".compatibility").tablesorter({theme:'blue',sortList:[[0,0]],widthFixed:true}); $("table.options").tablesorter({theme:'blue',sortList:[[0,0]],headers:{3:{sorter:false},4:{sorter:false}},widgets:['stickyHeaders'],widthFixed:true}); }); </script> <script type="text/javascript"> var _gaq = _gaq || []; _gaq.push(['_setAccount', 'UA-37565923-4']); _gaq.push(['_trackPageview']); (function() { var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true; ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s); })(); </script> </head> <body> <div id="pagewidth"> <div id="header-top" class="clearfix">  <div id="support-navigation"> <ul></ul> </div>   <div id="logo-top"> <a href="http://www.ciaaw.org"><img src="images/ciaaw.png" alt="Logo of the Atomic Weights Commission"></a> <a href="http://www.iupac.org" target="_blank"><img src="images/iupac.png" class="xx" alt="Logo of the International Union of Pure and Applied Chemistry"></a> </div>   <div id="main-navigation"> <ul> <li><a href="index.htm">Home</a></li> <li><a href="atomic-weights.htm">Atomic Weights</a></li> <li><a href="isotopic-abundances.htm">Isotopic Abundances</a></li> <li><a href="reference-materials.htm">Reference Materials</a></li> <li><a href="commission.htm">The Commission</a></li> <li><a href="info.htm">FAQ's</a></li> </ul> </div>  </div id="header-top">  <div id="breadcrumb"> <ul> <li><a href="index.htm">Other elements</a></li> </ul></div> <div id="content"> <div id="main-content"> <h1>Iridium</h1> <p> <table id="mytable" class="tablesorter"> <thead> <tr> <th>Isotope</th> <th>Atomic mass (Da)</th> <th>Isotopic abundance (amount fraction)</th> </tr> </thead> <tbody> <tr><td><sup>191</sup>Ir</td><td>190.960 591(9)</td><td>0.3723(9)</td></tr> <tr><td><sup>193</sup>Ir</td><td>192.962 924(9)</td><td>0.6277(9)</td></tr> </tbody> </table> <br> <p> In 1969, the Commission recommended <i>A</i><sub>r</sub>(Ir) = 190.22(3) based on a closer analysis of earlier mass-spectrometric determinations. In 1993, the Commission changed the recommended value for the standard atomic weight of iridium to <i>A</i><sub>r</sub>(Ir) = 192.217(3) based on recent high-precision measurements using both positive and negative thermal ionization mass spectrometry. This value was reaffirmed in 2017 and represents a significant improvement in the precision of the atomic weight and is in agreement with the previous measurements. </p> <h9><font color=red>SOURCE</font>  <a href="publications.htm#P3">Atomic weights of the elements: Review 2000</a> by John R de Laeter et al. <i>Pure Appl. Chem.</i> 2003 (75) 683-800<br>© IUPAC 2003</h9> </div>  <div id="support-content"> <img src="images/p-table/Ir.png"><p class="credit">CIAAW</p> <p class="caption"><strong>Iridium</strong><br> <i>A</i><sub>r</sub>(Ir) = 192.217(2) since 2017<br><br> The name derives from the Latin <i>Iris</i>, the Greek goddess of rainbows, because of the variety of colours in the element's salt solutions. Iridium and osmium were both discovered in a crude platinum ore in 1803 by the English chemist Smithson Tennant. Iridium was discovered independently by the French chemist H. V. Collet-Descotils, who actually published his paper one month before Tennant, but Tennant is given credit for the discovery, perhaps because he alone also found osmium in the ore. </p> </div id="support-content">  </div id="content">  <div id="push"></div></div id="pagewidth">  <div id="footer"> <img src="images/logo.png"><br><br> <a href="privacy.htm">Privacy policy</a>  |  <a href="impressum.htm">Impressum</a>  |  <a href="members.htm">Contact</a>  |  © CIAAW, 2007-2015 <br> </div>  </body></html>

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Atomic Weight of Iridium | Commission on Isotopic Abundances and Atomic Weights