Atomic ratio

<h2 id="atoms">Atoms</h2>
<p>Mathematically, the <i>atomic percent</i> is
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    {\displaystyle \mathrm {atomic\ percent} \ (\mathrm {i} )={\frac {N_{\mathrm {i} }}{N_{\mathrm {tot} }}}\times 100\ }
  
 %
<p>where <i>N</i>i are the number of atoms of interest and <i>N</i>tot are the total number of atoms, while the <i>atomic ratio</i> is
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    {\displaystyle \mathrm {atomic\ ratio} \ (\mathrm {i:j} )=\mathrm {atomic\ percent} \ (\mathrm {i} ):\mathrm {atomic\ percent} \ (\mathrm {j} )\ .}

<p>For example, the <i>atomic percent</i> of <a href="/facts/Hydrogen/BoYHjl0J">hydrogen</a> in <a href="/facts/Water/0lkXnJPK">water</a> (H2O) is at.%H2O = 2/3 x 100 ≈ 66.67%, while the <i>atomic ratio</i> of hydrogen to oxygen is <i>A</i>H:O = 2:1.
</p>
<h2 id="isotopes">Isotopes</h2>
<p>Another application is in <a href="/facts/Radiochemistry/vdL6AaCH">radiochemistry</a>, where this may refer to <a href="/facts/Isotopic_ratio/dGjaAwc9">isotopic ratios</a> or <a href="/facts/Isotopic_abundance/dGjaAwc9">isotopic abundances</a>. Mathematically, the <i>isotopic abundance</i> is
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    {\displaystyle \mathrm {isotopic\ abundance} \ (\mathrm {i} )={\frac {N_{\mathrm {i} }}{N_{\mathrm {tot} }}}\ ,}

<p>where <i>N</i>i are the number of atoms of the isotope of interest and <i>N</i>tot is the total number of atoms, while the <i>atomic ratio</i> is
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    {\displaystyle \mathrm {isotopic\ ratio} \ (\mathrm {i:j} )=\mathrm {isotopic\ percent} \ (\mathrm {i} ):\mathrm {isotopic\ percent} \ (\mathrm {j} )\ .}

<p>For example, the <i>isotopic ratio</i> of <a href="/facts/Deuterium/Bv4wfCkw">deuterium</a> (D) to <a href="/facts/Hydrogen/BoYHjl0J">hydrogen</a> (H) in <a href="/facts/Heavy_water/3dbSrTw5">heavy water</a> is roughly D:H = 1:7000 (corresponding to an <i>isotopic abundance</i> of 0.00014%).
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<h2 id="doping-in-laser-physics">Doping in laser physics</h2>
<p>In <a href="/facts/Laser_physics/VlHftEKg">laser physics</a> however, the <i>atomic ratio</i> may refer to the <a href="/facts/Dopant/DvChmeRL">doping</a> ratio or the doping fraction.
</p>
<ul><li>For example, theoretically, a 100% <i>doping ratio</i> of <a href="/facts/Ytterbium/3lerM9uf">Yb</a> : <a href="/facts/Yttrium_aluminium_garnet/U6m3FjcR">Y3Al5O12</a> is pure Yb3Al5O12.</li>
<li>The <i>doping fraction</i> equals,</li></ul>

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    {\displaystyle \mathrm {\frac {N_{\mathrm {atoms\ of\ dopant} }}{N_{\mathrm {atoms\ of\ solution\ which\ can\ be\ substituted\ with\ the\ dopant} }}} }

<h2 id="see-also">See also</h2>
<ul><li><a href="/facts/Concentration/wqBmz5od">Table of concentration measures</a></li></ul>

<h2 id="references">References</h2>

<ol>
<li id="fn:1"><p>McGraw-Hill Dictionary of Chemistry. McGraw-Hill. 27 January 2003. pp. 31. ISBN 0-07-141046-5. <a href="0-07-141046-5" target="_blank">0-07-141046-5</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li>
</ol>

Atomic ratio open-in-new

Atomic ratio