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When to use double and when to use triple bonds?

  1. Jun 27, 2006 #1
    I seemed to be confuse when to use double and triple bonds. For example, take CH2O and HCN. How do you know if you can use a triple or a double bond on the carbon and oxygen for CH2O? I know the correct answer is a double bond, with two lone pairs on the oxygen. And for HCN, it is a triple bond on the carbon and nitrogen with only one lone pair on the nitrogen.

    But how do you know when to use a triple or double? I am very confused.. is there a rule to know when you can use a double bond, and leave two lone pairs hanging out, or a triple bond with only one lone pair? Thanks.
  2. jcsd
  3. Jun 27, 2006 #2


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    Well consider the CH2O molecule. The carbon has four free electrons in its outer shell and 2 of those are used with the 2 Hydrogen atoms so it only has 2 bonds left and so forms a double bond with the oxygen. I hope this simple explaination has clarrified things.
  4. Jun 27, 2006 #3
    Oh. I'm so stupid. I almost forgot about that part. Thanks!
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