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Gen Chem Q

Discussion in 'DAT Discussions' started by topdent1, Jun 6, 2008.

  1. topdent1

    2+ Year Member

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    If 2 atoms are bonded together, one with six valence electrons, the other with 4, how many electrons must they share for both to achieve a full octet?

    The answer is 6 but I don't know why.
     
  2. Mstoothlady2012

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    Total electrons --> 6+4 =10
    Now you have to combine them in such a way that each atom fulfills the octet rule. In order to do that both atoms will have to form 3 covalent bonds (6 electrons) between them. Remaining 4 will be divided among two atoms; 2 for each. Hence now each atom has 8 electrons; 1 lone pair; and 6 shared electrons.
     
  3. DDSguyLA

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    WELL said.
    Add the total Valence electrons. Start with the bonds give as much then try to obey octet rule on each atom... a little mix and match will do the job.
     
  4. smile101

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    A more systematic way I learned in my gchm class is here:

    Suppose the two elements are X and Y

    Total valence e: 10
    so put X-Y
    Now, # available: 8 (bc you used 2 to form a single bond between the two)
    # required to fill the octet: 12 (6/ element)
    This means that you need 4 extra electrons than available (12-8=4), so put 2 extra bonds, which results in a triple bond between X and Y.
    These are all the bonds you will have, and you will put one extra pair of electrons on each one to use all the 10 electrons.

    Wish I had paper and pen to explain this, but oh well.
    Hope this helps!!
     

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