Turn on thread page Beta

Van der waals / Permanent dipole dipole interactions help ? watch

    • Thread Starter
    Offline

    18
    ReputationRep:
    Hey guys how would you know if a molecule has van der waals forces or permanent dipole dipole interactions ??
    In past papers they give you random molecules and expect you to find the force i always seem to struggle on those.
    So thank you for the help guysx
    Offline

    5
    ReputationRep:
    Pretty much all simple covalent molecules have induced London (Van de Waals) forces due to the shifting electron cloud, but there are only permanent dipole - dipole interractions when the overall molecule is polar
    Offline

    17
    ReputationRep:
    PDD is a type of VdW.

    Avoid VdW and just use the term London force.

    Look at the molecule. Ask yourself:
    Is it symmetrical (in 3D) and/or is is made of non-polar bonds (i.e. atoms of the same type), then it is London only.
    If it has polar bonds (different elements) AND is asymmetric, then you'll have PDD.
    Unless, you have N, O or F attached to H, in which case, you'll have H-bonds.
    • Thread Starter
    Offline

    18
    ReputationRep:
    (Original post by SCandium)
    Pretty much all simple covalent molecules have induced London (Van de Waals) forces due to the shifting electron cloud, but there are only permanent dipole - dipole interractions when the overall molecule is polar
    (Original post by Pigster)
    PDD is a type of VdW.

    Avoid VdW and just use the term London force.

    Look at the molecule. Ask yourself:
    Is it symmetrical (in 3D) and/or is is made of non-polar bonds (i.e. atoms of the same type), then it is London only.
    If it has polar bonds (different elements) AND is asymmetric, then you'll have PDD.
    Unless, you have N, O or F attached to H, in which case, you'll have H-bonds.
    Omg thank you guys
 
 
 
Reply
Submit reply
Turn on thread page Beta
Updated: March 5, 2018
The home of Results and Clearing

2,977

people online now

1,567,000

students helped last year

University open days

  1. Bournemouth University
    Clearing Open Day Undergraduate
    Wed, 22 Aug '18
  2. University of Buckingham
    Postgraduate Open Evening Postgraduate
    Thu, 23 Aug '18
  3. University of Glasgow
    All Subjects Undergraduate
    Tue, 28 Aug '18
Poll
How are you feeling about GCSE results day?

The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE

Write a reply...
Reply
Hide
Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.