{"id":489,"date":"2018-03-20T14:36:10","date_gmt":"2018-03-20T14:36:10","guid":{"rendered":"https:\/\/courses.lumenlearning.com\/suny-orgbiochemistry\/?post_type=chapter&p=489"},"modified":"2018-08-08T18:44:03","modified_gmt":"2018-08-08T18:44:03","slug":"4-3-multiple-covalent-bonds","status":"publish","type":"chapter","link":"https:\/\/courses.lumenlearning.com\/suny-monroecc-orgbiochemistry\/chapter\/4-3-multiple-covalent-bonds\/","title":{"raw":"4.3 Multiple Covalent Bonds","rendered":"4.3 Multiple Covalent Bonds"},"content":{"raw":"
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Learning Objective<\/h3>\r\n
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  1. Recognize molecules that are likely to have multiple covalent bonds.<\/li>\r\n<\/ol>\r\n<\/div>\r\n<\/div>\r\n

    In many molecules, the octet rule would not be satisfied if each pair of bonded atoms shares two electrons. Consider carbon dioxide (CO2<\/sub>). If each oxygen atom shares one electron with the carbon atom, we get the following:<\/p>\r\n\r\n

    \"image\"<\/div>\r\n

    This does not give the carbon atom a complete octet; you will find only six electrons in its valence shell. In addition, each oxygen atom has only seven electrons in its valence shell. Finally, no atom makes the number of bonds it typically forms (Figure 4.2 \"How Many Covalent Bonds Are Formed?\"<\/a>). This arrangement of shared electrons is far from satisfactory.<\/p>\r\n

    Sometimes more than one pair of electrons must be shared between two atoms for both atoms to have an octet. In carbon dioxide, a second electron from each oxygen atom is also shared with the central carbon atom, and the carbon atom shares one more electron with each oxygen atom:<\/p>\r\n\r\n

    \"image\"<\/div>\r\n

    In this arrangement, the carbon atom shares four electrons (two pairs) with the oxygen atom on the left and four electrons with the oxygen atom on the right. There are now eight electrons around each atom. Two pairs of electrons shared between two atoms make a double bond<\/span><\/span><\/strong>\u00a0between the atoms, which is represented by a double dash:<\/p>\r\n\r\n

    \"image\"<\/div>\r\n

    Some molecules contain triple bonds<\/span><\/span><\/strong>, covalent bonds in which three<\/em> pairs of electrons are shared by two atoms. A simple compound that has a triple bond is acetylene (C2<\/sub>H2<\/sub>), whose Lewis diagram is as follows:<\/p>\r\n\r\n

    \"image\"<\/div>\r\n
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    Example 5<\/h3>\r\n

    Draw the Lewis diagram for each molecule.<\/p>\r\n\r\n

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    1. N2<\/sub><\/li>\r\n \t
    2. CH2<\/sub>O (The carbon atom is the central atom.)<\/li>\r\n<\/ol>\r\n

      Solution<\/p>\r\n

      [reveal-answer q=\"366984\"]Show Answer[\/reveal-answer]\r\n[hidden-answer a=\"366984\"]<\/p>\r\n\r\n

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      1. The bond between the two nitrogen atoms is a triple bond. The Lewis diagram for N2 is as follows:\"image\"<\/li>\r\n \t
      2. In CH2<\/sub>O, the central atom is surrounded by two different types of atoms. The Lewis diagram that fills each atom\u2019s valence electron shell is as follows:<\/li>\r\n<\/ol>\r\n\"image\"[\/hidden-answer]\r\n

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        Notes<\/h3>\r\n

        One application of CH2<\/sub>O, also called formaldehyde, is the preservation of biological specimens. Aqueous solutions of CH2<\/sub>O are called formalin and have a sharp, characteristic (pungent) odor.<\/p>\r\n\r\n<\/div>\r\n<\/div>\r\n

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        Skill-Building Exercise<\/h3>\r\n
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          O2<\/sub><\/p>\r\n\r\n<\/div><\/li>\r\n \t

        2. \r\n
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          C2<\/sub>H4<\/sub><\/p>\r\n\r\n<\/div><\/li>\r\n<\/ol>\r\n<\/div>\r\n<\/div>\r\n

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          Concept Review Exercise<\/h3>\r\n
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          1. \r\n
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            What is one clue that a molecule has a multiple bond?<\/p>\r\n\r\n<\/div><\/li>\r\n<\/ol>\r\n<\/div>\r\n<\/div>\r\n

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            Answer<\/h3>\r\n[reveal-answer q=\"219902\"]Show Answer[\/reveal-answer]\r\n[hidden-answer a=\"219902\"]\r\n
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            1. If single bonds between all atoms do not give all atoms (except hydrogen) an octet, multiple covalent bonds may be present.[\/hidden-answer]<\/li>\r\n<\/ol>\r\n<\/div>\r\n
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              Key Takeaway<\/h3>\r\n
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