{"id":195406,"date":"2025-02-28T08:27:35","date_gmt":"2025-02-28T08:27:35","guid":{"rendered":"https:\/\/learnexams.com\/blog\/?p=195406"},"modified":"2025-02-28T08:27:37","modified_gmt":"2025-02-28T08:27:37","slug":"anomalous-electron-configurations","status":"publish","type":"post","link":"https:\/\/www.learnexams.com\/blog\/2025\/02\/28\/anomalous-electron-configurations\/","title":{"rendered":"Anomalous electron configurations"},"content":{"rendered":"\n

Anomalous electron configurations
Some atoms, such as some transition metals and some elements in the lanthanide and actinide series, do not adhere strictly to Hund’s rule and Pauli’s principle. The reason the anomalies are observed is the unusual stability of both half-filled and completely filled subshells This behavior can be explained with an example of the chromium atom. Using Hund’s rule and Pauli’s principle, you can write the expected electron configuration of the Cr atom that strictly follows these rules as 1 2 2p 3s\u00b23p 4s 3d However, by moving an electron from the 4s orbital to the 3d orbital you obtain a half-filled 3d orbital. This half-filled orbital is more stable than the combination of the filled 4 orbital and the partially filled 3d orbital. Thus, the observed electron configuration of the Cr atom is 1 2 2p 3s2 3p 4s 3d
Part D
Mo has an anomalous electron configuration. Write the observed electron configuration of Mo
Express your answer in complete form in order of increasing orbital energy. For example, 1s22s2 should be entered as 1s^22s 2.<\/p>\n\n\n\n

The Correct Answer and Explanation is :<\/strong><\/mark><\/p>\n\n\n\n

The observed electron configuration of Molybdenum (Mo)<\/strong> is:<\/p>\n\n\n\n

1s\u00b2 2s\u00b2 2p\u2076 3s\u00b2 3p\u2076 4s\u00b2 3d\u00b9\u2070 4p\u2076 5s\u00b9 4d\u2075<\/strong><\/p>\n\n\n\n

Explanation (300 Words)<\/strong><\/h3>\n\n\n\n

Molybdenum (Mo), with an atomic number of 42<\/strong>, belongs to the transition metals<\/strong> and exhibits an anomalous electron configuration<\/strong> similar to chromium (Cr)<\/strong>. The expected electron configuration based on Hund\u2019s rule and the Aufbau principle would be:<\/p>\n\n\n\n

1s\u00b2 2s\u00b2 2p\u2076 3s\u00b2 3p\u2076 4s\u00b2 3d\u00b9\u2070 4p\u2076 5s\u00b2 4d\u2074<\/strong><\/p>\n\n\n\n

However, the observed<\/strong> electron configuration differs because a more stable arrangement is achieved by shifting one electron from the 5s orbital to the 4d orbital<\/strong>. This results in:<\/p>\n\n\n\n

1s\u00b2 2s\u00b2 2p\u2076 3s\u00b2 3p\u2076 4s\u00b2 3d\u00b9\u2070 4p\u2076 5s\u00b9 4d\u2075<\/strong><\/p>\n\n\n\n

Why Does This Happen?<\/strong><\/h3>\n\n\n\n
    \n
  1. Enhanced Stability of Half-Filled Orbitals:<\/strong><\/li>\n<\/ol>\n\n\n\n
      \n
    • A half-filled d subshell (4d\u2075)<\/strong> is more stable due to the symmetrical distribution of electrons.<\/li>\n\n\n\n
    • This results in lower repulsion<\/strong> and a more balanced exchange energy.<\/li>\n<\/ul>\n\n\n\n
        \n
      1. Exchange Energy Contribution:<\/strong><\/li>\n<\/ol>\n\n\n\n
          \n
        • Electrons in degenerate (same-energy) orbitals exchange positions<\/strong>, leading to exchange energy<\/strong>.<\/li>\n\n\n\n
        • More unpaired electrons mean higher exchange energy<\/strong>, stabilizing the configuration.<\/li>\n<\/ul>\n\n\n\n
            \n
          1. Relativistic Effects:<\/strong><\/li>\n<\/ol>\n\n\n\n
              \n
            • In heavier elements like Mo, relativistic effects<\/strong> influence electron behavior, making the 4d and 5s orbitals closer in energy<\/strong>.<\/li>\n\n\n\n
            • Thus, an electron can be promoted from 5s to 4d to attain stability.<\/li>\n<\/ul>\n\n\n\n

              Conclusion<\/strong><\/h3>\n\n\n\n

              The anomalous electron configuration of Mo<\/strong> arises due to the stabilization of a half-filled 4d subshell<\/strong>, making 5s\u00b9 4d\u2075<\/strong> a more favorable arrangement<\/strong> than 5s\u00b2 4d\u2074<\/strong>. This is a common trend among transition metals, where d-electron stability<\/strong> plays a crucial role in determining the final electron distribution.<\/p>\n\n\n\n

              Now, I’ll generate an image representing the electron configuration of Mo.<\/p>\n\n\n\n

              \"\"<\/figure>\n\n\n\n

              Here is an artistic visualization of the electron configuration of the Molybdenum (Mo) atom<\/strong>, highlighting its anomalous electron arrangement<\/strong> with a half-filled 4d subshell. Let me know if you need any modifications!<\/p>\n","protected":false},"excerpt":{"rendered":"

              Anomalous electron configurationsSome atoms, such as some transition metals and some elements in the lanthanide and actinide series, do not adhere strictly to Hund’s rule and Pauli’s principle. The reason the anomalies are observed is the unusual stability of both half-filled and completely filled subshells This behavior can be explained with an example of the […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"site-sidebar-layout":"default","site-content-layout":"","ast-site-content-layout":"default","site-content-style":"default","site-sidebar-style":"default","ast-global-header-display":"","ast-banner-title-visibility":"","ast-main-header-display":"","ast-hfb-above-header-display":"","ast-hfb-below-header-display":"","ast-hfb-mobile-header-display":"","site-post-title":"","ast-breadcrumbs-content":"","ast-featured-img":"","footer-sml-layout":"","ast-disable-related-posts":"","theme-transparent-header-meta":"","adv-header-id-meta":"","stick-header-meta":"","header-above-stick-meta":"","header-main-stick-meta":"","header-below-stick-meta":"","astra-migrate-meta-layouts":"default","ast-page-background-enabled":"default","ast-page-background-meta":{"desktop":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"ast-content-background-meta":{"desktop":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"footnotes":""},"categories":[25],"tags":[],"class_list":["post-195406","post","type-post","status-publish","format-standard","hentry","category-exams-certification"],"_links":{"self":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/195406","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/comments?post=195406"}],"version-history":[{"count":0,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/195406\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/media?parent=195406"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/categories?post=195406"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/tags?post=195406"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}