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Topic: Van Der Waals  (Read 3689 times)

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Offline jsmith613

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Van Der Waals
« on: November 01, 2010, 10:03:42 AM »
do we say there are more Van Der Waals or stronger van der waal forces between iodine molecules than between bromine molecules

Offline Trave11er

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Re: Van Der Waals
« Reply #1 on: November 01, 2010, 03:10:47 PM »
Yes,

You see Wan der Waals forces are stronger when atom is more polarizable as in case of iodine. Because it is easier for I2 to create instant dipoles - you can imagine this that large iodine atoms have big and and have loose electron. These dipoles then  that would interact favourably (oposite charges attract each other).
If you want to learn more I recommend to read pp. 5-6 here http://www.oup.com/uk/orc/bin/9780199289301/ch01.pdf. It is a wonderful book - you won't regret it :).

Offline rabolisk

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Re: Van Der Waals
« Reply #2 on: November 01, 2010, 03:29:43 PM »
If you meant do we use the term more or stronger, I would generally say stronger.

Offline Trave11er

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Re: Van Der Waals
« Reply #3 on: November 01, 2010, 03:51:15 PM »
 ;D Oops

Offline jsmith613

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Re: Van Der Waals
« Reply #4 on: November 01, 2010, 05:05:35 PM »
If you meant do we use the term more or stronger, I would generally say stronger.

Do we ever get more van der waals between Iodine than between Bromine molecules

Offline cliverlong

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Re: Van Der Waals
« Reply #5 on: November 02, 2010, 04:43:01 AM »
Are following two links any use?

http://www.chemguide.co.uk/atoms/bonding/vdw.html
http://www.chemguide.co.uk/atoms/bonding/vdwstrengths.html#top


Especially the second on the relative strengths of the forces.

Notice two factors. The strength of an individual temporary / permanent dipole and the numbers of dipoles between molecules. Many small forces can be stronger than a single "large" force.

Clive

Offline jsmith613

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Re: Van Der Waals
« Reply #6 on: November 02, 2010, 08:29:45 AM »
The reason I am asking is because my chemistry teacher said there will be more Van Der Walls and they CAN't be stronger - I though he was incorrect so wanted to clarify!

Offline _rob

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Re: Van Der Waals
« Reply #7 on: November 06, 2010, 05:41:14 PM »
I would say you are correct, 'more' seems to imply poor understanding

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