{"id":231245,"date":"2025-06-10T18:00:00","date_gmt":"2025-06-10T18:00:00","guid":{"rendered":"https:\/\/learnexams.com\/blog\/?p=231245"},"modified":"2025-06-10T18:00:05","modified_gmt":"2025-06-10T18:00:05","slug":"question-4-identify-the-electron-configuration-for-the-alkaline-earth-metal-in-period-four","status":"publish","type":"post","link":"https:\/\/www.learnexams.com\/blog\/2025\/06\/10\/question-4-identify-the-electron-configuration-for-the-alkaline-earth-metal-in-period-four\/","title":{"rendered":"QUESTION 4 Identify the electron configuration for the alkaline earth metal in period four."},"content":{"rendered":"\n

QUESTION 4 Identify the electron configuration for the alkaline earth metal in period four. 1s\u00b22s\u00b22p?3s\u00b23p?4s\u00b9 1s\u00b22s\u00b22p?3s\u00b23p?4s\u00b24p\u00b9 1s\u00b22s\u00b22p?3s\u00b23p?4s\u00b2 1s\u00b22s\u00b22p?3s\u00b23d\u00b9?3p?4s\u00b2 1s\u00b22s\u00b23s\u00b24s\u00b2 QUESTION 5 What is the most likely charged state for a nitrogen ion with a filled valence shell of electrons? N\u00b3? N?? N?? N\u00b3? N?? QUESTION 6 Which of the following compounds is held together by covalent bonds, rather than ionic bonds? FeCl? CaCl? LiCl NCl? KCl<\/p>\n\n\n\n

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

Correct Answer:<\/strong> 1s\u00b22s\u00b22p\u20763s\u00b23p\u20764s\u00b2<\/p>\n\n\n\n

Explanation:<\/strong>
To identify the correct electron configuration, one must first determine the specific element being described. The periodic table is organized into periods (horizontal rows) and groups (vertical columns). “Period four” refers to the fourth row of the periodic table. The “alkaline earth metals” constitute Group 2 of the periodic table. The element located at the intersection of period four and Group 2 is Calcium (Ca).<\/p>\n\n\n\n

Calcium has an atomic number (Z) of 20, meaning a neutral calcium atom contains 20 electrons. The electron configuration is determined by filling the atomic orbitals in order of increasing energy, a principle known as the Aufbau principle.<\/p>\n\n\n\n

    \n
  1. The first energy level (n=1) has one s-orbital, which holds a maximum of 2 electrons:\u00a01s\u00b2<\/strong>.<\/li>\n\n\n\n
  2. The second energy level (n=2) has one s-orbital and three p-orbitals. These hold 2 and 6 electrons, respectively:\u00a02s\u00b22p\u2076<\/strong>. (10 total electrons)<\/li>\n\n\n\n
  3. The third energy level (n=3) fills its s- and p-orbitals next:\u00a03s\u00b23p\u2076<\/strong>. (18 total electrons)<\/li>\n\n\n\n
  4. According to the Aufbau principle, the 4s-orbital is lower in energy than the 3d-orbital. The remaining 2 electrons fill the 4s-orbital:\u00a04s\u00b2<\/strong>.<\/li>\n<\/ol>\n\n\n\n

    Combining these gives the complete ground-state electron configuration for calcium: 1s\u00b22s\u00b22p\u20763s\u00b23p\u20764s\u00b2<\/strong>.<\/p>\n\n\n\n

    \n\n\n\n

    QUESTION 5<\/strong><\/h3>\n\n\n\n

    What is the most likely charged state for a nitrogen ion with a filled valence shell of electrons?<\/strong><\/p>\n\n\n\n

    Correct Answer:<\/strong> N\u00b3\u207b<\/p>\n\n\n\n

    Explanation:<\/strong>
    The stability of an atom is greatly increased when its outermost electron shell (valence shell) is completely filled. This principle is often referred to as the octet rule, which states that atoms tend to gain, lose, or share electrons to achieve a stable configuration of eight valence electrons.<\/p>\n\n\n\n

    A neutral nitrogen atom (N) has an atomic number of 7. Its electron configuration is 1s\u00b22s\u00b22p\u00b3. The valence shell is the second energy level (n=2), which contains a total of 2 + 3 = 5 valence electrons.<\/p>\n\n\n\n

    To achieve a filled valence shell (an octet, or 8 electrons), a nitrogen atom has two theoretical options: lose its five valence electrons to form a N\u2075\u207a cation, or gain three electrons to form a N\u00b3\u207b anion. Nitrogen is a nonmetal with high electronegativity, meaning it has a strong attraction for electrons. It is far more energetically favorable for nitrogen to gain three electrons than to lose five.<\/p>\n\n\n\n

    By gaining three negatively charged electrons, the neutral nitrogen atom acquires an overall charge of 3- (7 protons, 10 electrons). This results in the formation of the nitride ion, N\u00b3\u207b<\/strong>, which has a stable, filled valence shell with the electron configuration 1s\u00b22s\u00b22p\u2076.<\/p>\n\n\n\n

    \n\n\n\n

    QUESTION 6<\/strong><\/h3>\n\n\n\n

    Which of the following compounds is held together by covalent bonds, rather than ionic bonds?<\/strong><\/p>\n\n\n\n

    Correct Answer:<\/strong> NCl\u2083<\/p>\n\n\n\n

    Explanation:<\/strong>
    The type of chemical bond that forms between two atoms is determined primarily by the difference in their electronegativity.<\/p>\n\n\n\n

    Ionic bonds<\/strong> typically form between a metal and a nonmetal. Metals have low electronegativity and tend to lose electrons, forming positive ions (cations). Nonmetals have high electronegativity and tend to gain electrons, forming negative ions (anions). The strong electrostatic attraction between these oppositely charged ions constitutes the ionic bond.<\/p>\n\n\n\n

    Covalent bonds<\/strong> typically form between two nonmetal atoms. Because nonmetals have similar, high electronegativities, neither atom can completely pull electrons away from the other. Instead, they achieve stable electron configurations by sharing one or more pairs of electrons.<\/p>\n\n\n\n

    Analyzing the options:<\/p>\n\n\n\n

      \n
    • FeCl\u2083, CaCl\u2082, LiCl, and KCl:<\/strong>\u00a0In each of these compounds, the first element (Iron, Calcium, Lithium, Potassium) is a metal, while chlorine (Cl) is a nonmetal. The large electronegativity difference between the metal and the nonmetal leads to the transfer of electrons and the formation of ionic bonds.<\/li>\n\n\n\n
    • NCl\u2083 (Nitrogen trichloride):<\/strong>\u00a0Both nitrogen (N) and chlorine (Cl) are nonmetals. They have relatively similar electronegativity values. To form a stable compound, they share electrons, creating covalent bonds. Each atom completes its octet through this sharing, resulting in a discrete NCl\u2083 molecule.<\/li>\n<\/ul>\n\n\n\n
      \"\"<\/figure>\n","protected":false},"excerpt":{"rendered":"

      QUESTION 4 Identify the electron configuration for the alkaline earth metal in period four. 1s\u00b22s\u00b22p?3s\u00b23p?4s\u00b9 1s\u00b22s\u00b22p?3s\u00b23p?4s\u00b24p\u00b9 1s\u00b22s\u00b22p?3s\u00b23p?4s\u00b2 1s\u00b22s\u00b22p?3s\u00b23d\u00b9?3p?4s\u00b2 1s\u00b22s\u00b23s\u00b24s\u00b2 QUESTION 5 What is the most likely charged state for a nitrogen ion with a filled valence shell of electrons? N\u00b3? N?? N?? N\u00b3? N?? QUESTION 6 Which of the following compounds is held together by […]<\/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-231245","post","type-post","status-publish","format-standard","hentry","category-exams-certification"],"_links":{"self":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/231245","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=231245"}],"version-history":[{"count":0,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/231245\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/media?parent=231245"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/categories?post=231245"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/tags?post=231245"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}