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Atoms with lots of bonds

  1. Jul 12, 2010 #1
    I was looking at sulfur hexafluoride and noticed that the sulfur forms 6 bonds with fluorine. Wouldn't 2 bonds put it at 8 valence electrons? How does it form so many extra bonds when it only needs 2?

    Edit: I should word this as "How does sulfur form 6 bonds with fluorine? Wouldn't that give it 12 valence electrons?"

    Thanks.
     
    Last edited: Jul 12, 2010
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  3. Jul 12, 2010 #2

    Ygggdrasil

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    Elements in period 3 and beyond can undergo a process known as valence shell expansion where the d-orbitals contribute to the valence shell.
     
  4. Jul 13, 2010 #3

    DrDu

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    No, the d-electrons play no role in the bonding of SF_6.
     
  5. Jul 13, 2010 #4

    Ygggdrasil

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    D-electrons do not play a role in the bonding of SF6, but sulfur's empty 3d orbitals do.
     
  6. Jul 13, 2010 #5
    How does an atom have empty orbitals? Empty meaning no electrons in it? How can it have orbitals without electrons? Aren't the electrons themselves orbitals?

    And wouldn't 6 bonds put the sulfur at 12 valence electrons? They want to be at 8, right?

    Thanks for the replies.
     
  7. Jul 13, 2010 #6
    Electrons are not themselves orbitals. In layman's terms, orbitals can be described as the slots which may or may not be occupied by electrons at any one time. An electron in an atom has a set of quantum states (n,l,ml,s). The values of n and l determine the kind of orbital (s,p,d,f,g...) the electron occupies, ml determines which orbital is occupied and s determines which of the two slots in the orbital is occupied by the electron.

    Orbitals may combine to form hybrid orbitals, which are linear combinations of "normal" orbitals. For example, an sp3d2-orbital, which is the type present in SF6, is a linear combination of one s-, three p-, and two d-orbitals.
     
  8. Jul 13, 2010 #7

    DrDu

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    This has long been disprooved. d-orbitals do not participate in the bonding in molecules like SF_6.
    I discussed this already in another thread https://www.physicsforums.com/showthread.php?t=405593&highlight=hybridization
    (is there a more direct way to cite an older thread?)

    For convenience here again the link to a more modern description
    :http://dx.doi.org/10.1016/S1380-7323(99)80022-3 [Broken]
     
    Last edited by a moderator: May 4, 2017
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