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url(../_media/elements/discharge/Ca.png) repeat-y center; background-size:contain;"> <span><a class="pure-menu-heading" href="https://winter.group.shef.ac.uk/webelements/"><img height="30" src="../_media/icons/logo_60.png" alt="WebElements logo"></a> <a class="white" href="./">Calcium - <sub>20</sub>Ca</a>  <audio id="myAudio_f"> <source src="../_media/elements/snds_f/Ca.mp3" type="audio/mpeg">Your user agent does not support the HTML5 Audio element. </audio> <button class="pure-button s_button" style=" display: inline;" type="button" onclick="audf_play_pause()"> 🔊  </button> <script> function audf_play_pause() { var myAudiof = document.getElementById("myAudio_f"); if (myAudiof.paused) { myAudiof.play(); } else { myAudiof.pause(); }} </script></span> </div> </div> </div> <div id="main">  <div class="pure-u-1 pure-u-sm-1-1"> <div class="pure-menu pure-menu-horizontal pure-menu-scrollable"> <a href="#" class="pure-menu-link pure-menu-heading">▸▸</a> <ul class="pure-menu-list"> <li class="pure-menu-item">🇬🇧 Calcium</li> <li class="pure-menu-item">🇺🇦 Кальцій</li> <li class="pure-menu-item">🇨🇳 鈣</li> <li class="pure-menu-item">🇳🇱 Calcium</li> <li class="pure-menu-item">🇫🇷 Calcium</li> <li class="pure-menu-item">🇩🇪 Calcium</li> <li class="pure-menu-item">🇮🇱 סידן</li> <li class="pure-menu-item">🇮🇹 Calcio</li> <li class="pure-menu-item">🇯🇵 カルシウム</li> <li class="pure-menu-item">🇵🇹 Cálcio</li> <li class="pure-menu-item">🇪🇸 Calcio</li> <li class="pure-menu-item">🇸🇪 Kalcium</li> <li class="pure-menu-item">🇷🇺 Кальций</li> </ul> </div> </div> <div class="pure-g"> <div class="pure-u-1 pure-u-sm-1-1"> <div class="google_navbar_positioning"> <form action="https://www.google.com" id="cse-search-box"> <div> <input type="hidden" name="cx" value="partner-pub-9334432533380510:6223510783"> <input type="hidden" name="ie" value="UTF-8"> <input type="text" name="q" size="28"> <input type="submit" name="sa" value="Search"> </div> </form> <script> </script> </div> </div> </div> <main> <div class="pure-g"> <div class="pure-u-1 pure-u-sm-1-1"> <h1 class="s">Calcium - <sub><small>20</small></sub>Ca: properties of free atoms</h1> <div class="pure-menu pure-menu-horizontal pure-menu-scrollable"> <ul class="pure-menu-list z_menu"> <li class="pure-menu-item s"><a href="../calcium/" class="pure-menu-link">▸▸ Ca Essentials</a></li> <li class="pure-menu-item s"><a class="pure-menu-link" href="../calcium/physics.html">Physical properties</a></li> <li class="pure-menu-item s"><a class="pure-menu-link" href="../calcium/atoms.html">Electron shell data</a></li> <li class="pure-menu-item s"><a class="pure-menu-link" href="../calcium/atom_sizes.html">Atom sizes</a></li> <li class="pure-menu-item s"><a class="pure-menu-link" href="../calcium/electronegativity.html">Electronegativity</a></li> <li class="pure-menu-item s"><a class="pure-menu-link" href="../calcium/isotopes.html" >Isotopes and NMR</a></li> <li class="pure-menu-item s"><a class="pure-menu-link" href="../calcium/crystal_structure.html">Crystal structure</a></li> <li class="pure-menu-item s"><a class="pure-menu-link" href="../calcium/thermochemistry.html">Thermochemistry</a></li> <li class="pure-menu-item s"><a class="pure-menu-link" href="../calcium/history.html">History</a></li> <li class="pure-menu-item s"><a class="pure-menu-link" href="../calcium/uses.html">Uses</a></li> <li class="pure-menu-item s"><a class="pure-menu-link" href="../calcium/geology.html">Geology</a></li> <li class="pure-menu-item s"><a class="pure-menu-link" href="../calcium/biology.html">Biology</a></li> <li class="pure-menu-item s"><a class="pure-menu-link" href="../calcium/compounds.html">Binary compounds</a></li> <li class="pure-menu-item s"><a class="pure-menu-link" href="../calcium/compound_properties.html" >Compound properties</a></li> <li class="pure-menu-item s"><a class="pure-menu-link" href="../calcium/chemistry.html">Element reactions</a></li> <li class="pure-menu-item s"><a class="pure-menu-link" href="../calcium/contents.html">List all Ca properties</a></li> </ul> </div> </div> </div> <p class="p_first">Calcium atoms have 20 electrons and the <strong><a href="../periodicity/electron_shell_structure/">shell structure</a></strong> is  2.8.8.2.</p> <p>The <strong><a href="../periodicity/electronic_configuration/">ground state electron configuration of ground state gaseous neutral calcium is</a></strong>  [<strong>Ar</strong>].<strong>4s</strong><sup>2</sup> and the <strong><a href="../periodicity/term_symbol/">term symbol</a></strong> is  <sup>1</sup><strong>S</strong><sub>0</sub>.</p> <div class="pure-g"> <div class="pure-u-1 pure-u-md-1-2"> <div><figure><img class="pure-img" src="../_media/elements/electronic_configuration/electronic_configuration_Ca.png" alt="Kossel shell structure of calcium" /><figcaption>Schematic electronic configuration of calcium.</figcaption></figure ></div> </div> <div class="pure-u-1 pure-u-md-1-2"> <div><figure><img class="pure-img" src="../_media/elements/kossel_diagrams/kossel-atom_Ca.png" alt="Kossel shell structure of calcium" /><figcaption>The Kossel shell structure of calcium.</figcaption></figure ></div> </div> </div> <h2 class="s">Atomic spectrum</h2> <div style="background: black url(../_media/elements/discharge/Ca.png) repeat-y center; background-size:contain;"> </div> <p>A representation of the atomic spectrum of calcium.</p> <h2 class="s">Ionisation Energies and electron affinity</h2> <p class="p_first">The <a href="../periodicity/electron_affinity/">electron affinity</a> of calcium is 2.37 kJ mol<sup>‑1</sup>. The <a href="../periodicity/ionisation_energy/">ionisation energies</a> of calcium are given below.</p> <div class="pure-g"> <div class="pure-u-1 pure-u-md-1-2"> <div class="table-responsive"> <table class="pure-table pure-table-striped"> <caption>Ionisation energies of calcium</caption> <thead> <tr> <th>Ionisation energy number</th> <th>Enthalpy / kJ mol<sup>‑1</sup></th> </tr> </thead> <tbody> <tr><td><a href="../periodicity/ionis_energy_1/">1st</a></td><td>589.83</td></tr> <tr><td><a href="../periodicity/ionis_energy_2/">2nd</a></td><td>1145.45</td></tr> <tr><td><a href="../periodicity/ionis_energy_3/">3rd</a></td><td>4912.37</td></tr> <tr><td><a href="../periodicity/ionis_energy_4/">4th</a></td><td>6490.9</td></tr> <tr><td><a href="../periodicity/ionis_energy_5/">5th</a></td><td>8140</td></tr> <tr><td><a href="../periodicity/ionis_energy_6/">6th</a></td><td>10500</td></tr> <tr><td><a href="../periodicity/ionis_energy_7/">7th</a></td><td>12270</td></tr> <tr><td><a href="../periodicity/ionis_energy_8/">8th</a></td><td>14210</td></tr> <tr><td><a href="../periodicity/ionis_energy_9/">9th</a></td><td>18190</td></tr> <tr><td><a href="../periodicity/ionis_energy_10/">10th</a></td><td>20380</td></tr> <tr><td><a href="../periodicity/ionis_energy_11/">11th</a></td><td>57080</td></tr> <tr><td><a href="../periodicity/ionis_energy_12/">12th</a></td><td>63510 (inferred)</td></tr> <tr><td><a href="../periodicity/ionis_energy_13/">13th</a></td><td>70300</td></tr> <tr><td><a href="../periodicity/ionis_energy_14/">14th</a></td><td>78850</td></tr> <tr><td><a href="../periodicity/ionis_energy_15/">15th</a></td><td>86260</td></tr> <tr><td><a href="../periodicity/ionis_energy_16/">16th</a></td><td>93950</td></tr> <tr><td><a href="../periodicity/ionis_energy_17/">17th</a></td><td>105000</td></tr> <tr><td><a href="../periodicity/ionis_energy_18/">18th</a></td><td>111704</td></tr> <tr><td><a href="../periodicity/ionis_energy_19/">19th</a></td><td>494859</td></tr> <tr><td><a href="../periodicity/ionis_energy_20/">20th</a></td><td>527761</td></tr> </tbody> </table> </div> </div> <div class="pure-u-1 pure-u-md-1-2"> <div class="kossel_div"></figure><img class="pure-img" src="../_media/elements/ionisation_energies/ionisation_energies_Ca.png" alt="Ionisation energies of calcium" /><figcaption>Ionisation energies of calcium.</figcaption></figure></div> </div> </div> <div class="pure-g"> <div class="pure-u-1 pure-u-sm-1-1"> <script async src="//pagead2.googlesyndication.com/pagead/js/adsbygoogle.js"></script>  <ins class="adsbygoogle" style="display:block" data-ad-client="ca-pub-9334432533380510" data-ad-slot="4479092381" data-ad-format="auto"></ins> <script> (adsbygoogle = window.adsbygoogle || []).push({}); </script> </div> </div> <h2 class="s">Effective Nuclear Charges</h2> <p>The following are "<a href="../periodicity/eff_nuc_charge_clementi/">Clementi-Raimondi</a>" effective nuclear charges, <em>Z</em><sub>eff</sub>. Follow the hyperlinks for more details and for graphs in various formats.</p> <div class="table-responsive"> <table class="pure-table pure-table-striped"> <caption>Effective nuclear charges for calcium</caption> <tbody> <tr> <th><a href="../periodicity/eff_nuc_chg_clem_1s/">1s</a></th><td>19.4730</td> <td colspan="6"> </td> </tr> <tr> <th><a href="../periodicity/eff_nuc_chg_clem_2s/">2s</a></th><td>13.78</td> <th><a href="../periodicity/eff_nuc_chg_clem_2p/">2p</a></th><td>16.04</td> <td colspan="4"> </td> </tr> <tr> <th><a href="../periodicity/eff_nuc_chg_clem_3s/">3s</a></th><td>9.60</td> <th><a href="../periodicity/eff_nuc_chg_clem_3p/">3p</a></th><td>8.66</td> <th><a href="../periodicity/eff_nuc_chg_clem_3d/">3d</a></th><td>(no data)</td> <td colspan="2"> </td> </tr> <tr> <th><a href="../periodicity/eff_nuc_chg_clem_4s/">4s</a></th><td>4.40</td> <th><a href="../periodicity/eff_nuc_chg_clem_4p/">4p</a></th><td>(no data)</td> <th><a href="../periodicity/eff_nuc_chg_clem_4d/">4d</a></th><td>(no data)</td> <th><a href="../periodicity/eff_nuc_chg_clem_4f/">4f</a></th><td>(no data)</td> </tr> <tr> <th><a href="../periodicity/eff_nuc_chg_clem_5s/">5s</a></th><td>(no data)</td> <th><a href="../periodicity/eff_nuc_chg_clem_5p/">5p</a></th><td>(no data)</td> <th><a href="../periodicity/eff_nuc_chg_clem_5d/">5d</a></th><td>(no data)</td> <td colspan="2"> </td> </tr> <tr> <th><a href="../periodicity/eff_nuc_chg_clem_6s/">6s</a></th><td>(no data)</td> <th><a href="../periodicity/eff_nuc_chg_clem_6p/">6p</a></th><td>(no data)</td> <td colspan="4"> </td> </tr> <tr> <th>7s</th><td> </td> <td colspan="6"> </td> </tr> </tbody> </table> </div> <h3 class="s">References</h3> <p>These effective nuclear charges, <em>Z</em><sub>eff</sub>, are adapted from the following references:</p> <ol> <li>E. Clementi and D.L.Raimondi, <em>J. Chem. Phys.</em> 1963, <strong>38</strong>, 2686.</li> <li>E. Clementi, D.L.Raimondi, and W.P. Reinhardt, <em>J. Chem. Phys.</em> 1967, <strong>47</strong>, 1300.</li> </ol> <h2 class="s">Electron binding energies</h2> <table class="pure-table pure-table-striped"> <caption>Electron binding energies for calcium. All values of <a href="../periodicity/elec_binding_energy/">electron binding energies</a> are given in eV. The binding energies are quoted relative to the vacuum level for rare gases and H<sub>2</sub>, N<sub>2</sub>, O<sub>2</sub>, F<sub>2</sub>, and Cl<sub>2</sub> molecules; relative to the Fermi level for metals; and relative to the top of the valence band for semiconductors.</caption> <thead> <tr> <th>Label</th> <th>Orbital</th> <th>eV [literature reference]</th> </tr> </thead> <tbody> <tr><td>K </td><td><a href="../periodicity/e_bind_energy_K/">1s</a></td><td>4038.5 [2]</td></tr> <tr><td>L <sub>I</sub></td><td><a href="../periodicity/e_bind_energy_L_I/">2s</a></td><td>438.4 [3]</td></tr> <tr><td>L <sub>II</sub></td><td><a href="../periodicity/e_bind_energy_L_II/">2p<sub>1/2</sub></a></td><td>349.7 [3]</td></tr> <tr><td>L <sub>III</sub></td><td><a href="../periodicity/e_bind_energy_L_III/">2p<sub>3/2</sub></a></td><td>346.2 [3]</td></tr> <tr><td>M <sub>I</sub></td><td><a href="../periodicity/e_bind_energy_M_I/">3s</a></td><td>44.3 [3]</td></tr> <tr><td>M <sub>II</sub></td><td><a href="../periodicity/e_bind_energy_M_II/">3p<sub>1/2</sub></a></td><td>25.4 [3]</td></tr> <tr><td>M <sub>III</sub></td><td><a href="../periodicity/e_bind_energy_M_III/">3p<sub>3/2</sub></a></td><td>25.4 [3]</td></tr> </tbody> </table> <h3 class="s">Notes</h3> <p>I am grateful to <a href="http://www.jlab.org/%7Egwyn/">Gwyn Williams</a> (Jefferson Laboratory, Virginia, USA) who provided the electron binding energy data. The data are adapted from references 1-3. They are tabulated elsewhere on the WWW (reference 4) and in paper form (reference 5).</p> <h3 class="s">References</h3> <ol> <li>J. A. Bearden and A. F. Burr, "Reevaluation of X-Ray Atomic Energy Levels," <em>Rev. Mod. Phys.</em>, 1967, <strong>39</strong>, 125.</li> <li>M. Cardona and L. Ley, Eds., <em>Photoemission in Solids I: General Principles</em> (Springer-Verlag, Berlin) with additional corrections, 1978.</li> <li><a href="http://www.jlab.org/%7Egwyn/ebindene.html">Gwyn Williams WWW table of values</a></li> <li>D.R. Lide, (Ed.) in <em><a href="http://www.amazon.com/exec/obidos/ASIN/0849304814/webelements">Chemical Rubber Company handbook of chemistry and physics</a></em>, CRC Press, Boca Raton, Florida, USA, 81st edition, 2000. </li> <li>J. C. Fuggle and N. Mårtensson, "Core-Level Binding Energies in Metals," <em>J. Electron Spectrosc. Relat. Phenom.</em>, 1980, <strong>21</strong>, 275.</li> </ol> </main> <div id="footer"> <footer> <div class="footer"> <div class="pure-g"> <div class="pure-u-1-2 pure-u-sm-1-2 pure-u-lg-1-4 pure-menu custom-restricted-width"> <ul class="pure-menu-list"> <li class="pure-menu-heading footer_h">Key properties</li> <li class="pure-menu-item"><a class="pure-menu-link" href="https://www.webelements.com/periodicity/eneg_pauling/">Electronegativity </a></li> <li class="pure-menu-item"><a class="pure-menu-link" href="https://www.webelements.com/periodicity/melting_point/">Melting point</a></li> <li class="pure-menu-item"><a class="pure-menu-link" href="https://www.webelements.com/periodicity/density/">Density </a></li> <li class="pure-menu-item"><a class="pure-menu-link" href="https://www.webelements.com/periodicity/molar_volume/">Molar volume</a></li> <li class="pure-menu-item"><a class="pure-menu-link" href="https://www.webelements.com/periodicity/ionis_energy_1/">Ionization energy (1st)</a></li> <li class="pure-menu-item"><a class="pure-menu-link" href="https://www.webelements.com/periodicity/covalent_radius/">Covalent radius</a></li> <li class="pure-menu-item"><a class="pure-menu-link" href="https://www.webelements.com/periodicity/metallic_radius/">Metallic radius</a></li> <li class="pure-menu-item"><a class="pure-menu-link" href="https://www.webelements.com/periodicity/abund_crust/">Abundance: earth's crust</a></li> </ul> </div> <div class="pure-u-1-2 pure-u-sm-1-2 pure-u-lg-1-4 pure-menu custom-restricted-width"> <ul class="pure-menu-list"> <li class="pure-menu-heading footer_h">Shop</li> <li class="pure-menu-item">Sorry, shop closed</li> </ul> </div> <div class="pure-u-1-2 pure-u-sm-1-2 pure-u-lg-1-4 pure-menu custom-restricted-width"> <ul class="pure-menu-list"> <li class="pure-menu-heading footer_h">Social</li> <li class="pure-menu-item"><a class="pure-menu-link" href="https://www.facebook.com/webelements.periodic.table">Facebook</a></li> <li class="pure-menu-item"><a class="pure-menu-link" href="https://twitter.com/periodic_table">Twitter</a></li> <li class="pure-menu-item"><a class="pure-menu-link" href="https://www.pinterest.com/periodictable/">Pinterest</a></li> </ul> </div> <div class="pure-u-1-2 pure-u-sm-1-2 pure-u-lg-1-4 pure-menu custom-restricted-width"> <ul class="pure-menu-list"> <li class="pure-menu-heading footer_h">Administration</li> <li class="pure-menu-item"><a class="pure-menu-link" href="https://www.webelements.com/nexus/your-privacy/" title="Your privacy">Privacy</a></li> <li class="pure-menu-item"><a class="pure-menu-link" href="https://www.webelements.com/nexus/about-webelements/" title="About WebElements">About</a></li> <li class="pure-menu-item"><a class="pure-menu-link" href="https://www.webelements.com/nexus/webelements-and-copyright/" title="Copyright information about WebElements">Copyright</a></li> <li class="pure-menu-item"><a class="pure-menu-link" href="https://www.webelements.com/nexus/acknowledgements/" title="Acknowledgements">Thanks...</a></li> </ul> </div> </div> </div> <address> <p> <a href="https://www.webelements.com/"><img class="logo_m" src="../_media/icons/logo_60.png" alt="WebElements home" /></a><br /> <strong>WebElements:</strong> THE periodic table on the WWW [<a href="https://www.webelements.com/">www.webelements.com</a>]<br /> <a href="https://www.webelements.com/nexus/webelements-and-copyright/">Copyright </a> 1993-2024 <a href="https://winter.group.shef.ac.uk/">Mark Winter</a> [ <a href="https://www.sheffield.ac.uk/chemistry/">The University of Sheffield </a> and WebElements Ltd, UK]. 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