{"id":220106,"date":"2025-05-27T13:43:05","date_gmt":"2025-05-27T13:43:05","guid":{"rendered":"https:\/\/learnexams.com\/blog\/?p=220106"},"modified":"2025-05-27T13:43:07","modified_gmt":"2025-05-27T13:43:07","slug":"how-many-unpaired-electrons-are-in-the-ground-state-electron-configuration-of-selenium","status":"publish","type":"post","link":"https:\/\/www.learnexams.com\/blog\/2025\/05\/27\/how-many-unpaired-electrons-are-in-the-ground-state-electron-configuration-of-selenium\/","title":{"rendered":"How many unpaired electrons are in the ground state electron configuration of selenium"},"content":{"rendered":"\n

How many unpaired electrons are in the ground state electron configuration of selenium?<\/p>\n\n\n\n

Enter your answer as a number symbol (i.e. 1 or 3 or 5) not as a word (one or three or five).<\/p>\n\n\n\n

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

Answer:<\/strong> 2<\/p>\n\n\n\n

\n\n\n\n

Explanation:<\/strong><\/p>\n\n\n\n

Selenium (Se) has an atomic number of 34<\/strong>, meaning it has 34 electrons<\/strong> in its neutral ground state. To determine how many unpaired electrons<\/strong> it has, we need to examine its electron configuration<\/strong> and apply Hund\u2019s Rule<\/strong> and the Pauli Exclusion Principle<\/strong>.<\/p>\n\n\n\n

Step 1: Determine the Electron Configuration<\/h3>\n\n\n\n

The ground-state electron configuration of selenium is:<\/p>\n\n\n\n

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

Breaking it down:<\/p>\n\n\n\n

    \n
  • The core electrons (1s\u00b2 to 3p\u2076) are all in filled subshells with paired electrons.<\/li>\n\n\n\n
  • The 4s\u00b2<\/strong> and 3d\u00b9\u2070<\/strong> subshells are also completely filled.<\/li>\n\n\n\n
  • The 4p\u2074<\/strong> subshell is where the unpaired electrons occur.<\/li>\n<\/ul>\n\n\n\n

    Step 2: Focus on the 4p Subshell<\/h3>\n\n\n\n

    The p-subshell<\/strong> can hold a maximum of 6 electrons<\/strong> in three orbitals (p\u2093, p\u1d67, p_z), with each orbital capable of holding 2 electrons of opposite spin.<\/p>\n\n\n\n

    In selenium, the 4p\u2074<\/strong> subshell has 4 electrons<\/strong>. According to Hund’s Rule<\/strong>, electrons occupy orbitals singly first before pairing. So:<\/p>\n\n\n\n

      \n
    • The first 3 electrons go into 3 separate p orbitals: \u2191 \u2191 \u2191<\/li>\n\n\n\n
    • The 4th electron must pair with one of them: \u2191\u2193 \u2191 \u2191<\/li>\n<\/ul>\n\n\n\n

      So, there are 2 unpaired electrons<\/strong> in the 4p subshell.<\/p>\n\n\n\n

      Step 3: Total Unpaired Electrons<\/h3>\n\n\n\n

      All other subshells (1s, 2s, 2p, 3s, 3p, 3d, 4s) are fully filled and have no unpaired electrons. Only the 4p\u2074 contributes unpaired electrons.<\/p>\n\n\n\n

      Therefore, selenium has 2 unpaired electrons<\/strong> in its ground-state electron configuration.<\/p>\n\n\n\n

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

      Understanding the electron configuration and using Hund’s Rule helps us conclude that the number of unpaired electrons in selenium is 2<\/strong>, which influences its chemical reactivity<\/strong>, magnetic properties<\/strong>, and bonding behavior<\/strong>.<\/p>\n\n\n\n

      \"\"<\/figure>\n","protected":false},"excerpt":{"rendered":"

      How many unpaired electrons are in the ground state electron configuration of selenium? Enter your answer as a number symbol (i.e. 1 or 3 or 5) not as a word (one or three or five). The Correct Answer and Explanation is: Answer: 2 Explanation: Selenium (Se) has an atomic number of 34, meaning it has […]<\/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-220106","post","type-post","status-publish","format-standard","hentry","category-exams-certification"],"_links":{"self":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/220106","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=220106"}],"version-history":[{"count":0,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/220106\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/media?parent=220106"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/categories?post=220106"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/tags?post=220106"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}