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Single, Double, & Triple Bond ?

Discussion in 'MCAT Discussions' started by USArmyDoc, Jul 30, 2005.

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  1. USArmyDoc

    USArmyDoc

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    Bond length:

    Single>Double> Triple Bond? I always under the impression that single bonds were the shortests and strongest. However, in the EK 1001 Gen Chem book it says the single bonds are the longest.
  2. jon stewart

    jon stewart Senior Member

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    i think double bonds are the strongest, im not 100% sure tho

    A gen chem book should have the answer....
  3. USArmyDoc

    USArmyDoc

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    I got confused. I am pretty sure triple bonds are the strongest then double then single. If you think about it, a triple bond has one sigma and two pi bonds. Double has one of each and a single just has a sigma. Its the opposite though for stability. Single bonds are the most stable.
  4. DrChandy

    DrChandy

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    In terms of strength,
    triple>double>single

    In terms of bond length,
    single>double>triple
  5. USArmyDoc

    USArmyDoc

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    Chandy,
    You are the best. I eventually understood it. I was getting confused between stability, strength and length. No biggie. ;)
  6. toxin

    toxin Senior Member

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    A single bond consists of a sigma electron could (orbital)....which in itself is the strongest type of bonding. But, when you create a double you are adding a pi orbital (which is weaker than sigma orbital), since the pi orbital is being added to an existing sigma orbital it logically follows that it will be a stronger one (pi and sigma > sigma), the effect of the pi orbital will be strengthening the overall bond (double bond) but also shortening the distance between the atoms,which means shorter bond. Triple bond on the other hand adds another pi orbital to the existing sigma and pi orbitals making the triple bond stronger than the previous two and also shorter.

    Also note, that a double bond is not twice as strong as a single bond since we are not adding an additional sigma orbital, but a pi orbital (which is weaker), same logic extends to a triple bond.

    Hope that helps.
  7. Amandeep

    Amandeep Having MCAT nightmares!

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    I just wanted to add that:

    You can only compare bond strength & bond length in relation to bond order for similar bonds only (e.g C-0, C=O, C triple bond to O)
  8. DrBowtie

    DrBowtie Responsible?!?! PGY3 Moderator Emeritus

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    If you think of coulombs law.
    The F is inversely related to the distance.
    F is bond strength and distance is bond length.
  9. rs76

    rs76 Member

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    In terms of stability of the bonds, how is the order?

    single>double>triple

    For length,
    single>double>triple

    For strenght:
    triple>double>single

    I alwasy thought that since the triple bond is the strongest it must be the most stable since it is harder to break the triple bond. I am not sure. Any help is appreciated!
  10. DrBowtie

    DrBowtie Responsible?!?! PGY3 Moderator Emeritus

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    I would think stability would be the same as strength. More bonds equal less movement around the central atom? also since triple is the shortest and has more charges interacting, they should have the most stability.

    I might be wrong....can anyone confirm?
  11. USArmyDoc

    USArmyDoc

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    In the EK 1001 Organic chemistry book, they say the sigma bond is the most stable. They are the last to break in a reaction.
  12. toxin

    toxin Senior Member

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    You're correct Brett.

    Sigma is stronger than pi, but since triple bonds contain two pi and a sigma bond they are the strongest/shortest/most stable
  13. USArmyDoc

    USArmyDoc

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    Oh, I got ya. I was thinking individual bonds (e.g sigma, pi bonds alone). Yes, it would make sense that a triple bond would be most stable and when that triple bond is being broken to sigma bonds not the two pi bonds are broken last. I hope that makes sense.
  14. Will Hunting

    Will Hunting Aspiring Cardiologist

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    Gen chem brings back good memories. indeed Trip>doub> single.

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