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Normal electron configuration Ethyne

  1. Dec 24, 2004 #1
    This is a multiple choice question with the shown triple bond between the two carbons:

    I've narrowed it down to 2 diagrams
    a) ..
    C :: C

    b) C : : : C

    is it a). Please tell me if it's right. Thanks
  2. jcsd
  3. Dec 24, 2004 #2


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    If the question you're asking is whether a triple bond is indicated with 2 columns of 3 electrons each or 3 columns of 2 electrons each, then the answer is b.
    Single bond- C:C; double bond- C::C; triple bond- C:::C
  4. Dec 24, 2004 #3
    I'm not too sure about that. How are you judging the answer by? I'll give out all the choices now;

    a) H:C::C:H
    ____. ._. .
    b) H:C : C :H

    (the period represents one electron)
    c) H.C:::C.H
    _____ ..
    d) H:C::C:H

    e)H:C: C: H

    According to t!m the answer is c), but that wouldn't make any sense for the electrons shared by the hydrogens and carbons. i think the answer is d)
    Last edited: Dec 24, 2004
  5. Dec 25, 2004 #4


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    Ethyne has the chemical formula

    [tex] H-C\equiv C-H [/tex]
    ,where the triple bond assumes 3 pairs of electrons (6 electrons in total)shared by the 2 C atoms.Three chemical bonds:eek:ne sigma and 2 pi.Hybridization of the C atom:sp.

  6. Dec 25, 2004 #5
    Remember valency of carbon is 4.So two C atoms and 2H atoms have 2*4 + 2*1=10 electrons.try to arrange them so that all except H is surrounded by 8 and H by 2.
    So the answer is H:C:::C:H
  7. Dec 25, 2004 #6
    A single bond is shown as:
    [tex]Cl\begin{array}{cc}+\\\times\end{array} Cl[/tex] but with the other electrons around the Chlorine atoms.

    A double bond is shown as:
    [tex]O\begin{array}{cc}+\\\times\\+\\\times\end{array} O[/tex] but with the other electrons around the Oxygen atoms.

    A triple bond is shown as:
    [tex]H\begin{array}{cc}+\\\times\end{array} C\begin{array}{cc}+\\\times\\+\\\times\\+\\\times\end{array} C\begin{array}{cc}+\\\times\end{array} H[/tex]

    The Bob (2004 ©)
  8. Dec 25, 2004 #7
    There's not even a choice like that.... look carefully... I think agree with the Bob..
  9. Dec 25, 2004 #8


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    Gold Member

    This is merely a question of representation. What everyone's trying to say, is that the C atoms in ethyne are bonded to each other by a triple bond. How you represent this triple bond doesn't matter terribly, as long as the other person knows what you mean. The standard representation, however, would be either what Dexter has used (common for designating organic compounds) or what The Bob has used (known as Lewis Dot Structures, these are used specifically when solving problems on electronic configurations).

    The important thing to learn here, however, is what poolwin has mentioned : that the triple (covalent) bond is the only structure that ensures an octet for C and a duet for the H atom. So, while the representation of the structure is useful for effective communication, understanding the 'why' of the structure is more important.
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