Have a Question Rlated to Chemistry... I know this is for MCAT questions... But Desperate!

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Oct 22, 2014
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Okay don't make fun of me for asking this, even if it's extremely easy for you, but I have a test tomorrow and cannot figure this out. How do you figure out if a nonpolar compound is a dipole- dipole attraction, dispersion force or hydrogen bond? I have some example but am unsure why they are named this way.
#1. Ex. of a dipole- dipole attraction - HCl, HI, and HBr
#2. Ex. of dispersion force - Br(subscript)2 , CH(subscript)4, and F 2.
#3. Ex. of hydrogen bond - H2O, and NH3
 
Oct 10, 2014
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If my memory serves me for:
#1. A dipole bond depends on electronegativity differences between different elements, atoms, or compounds, which results in the electrons in the bond spending more time around one atoms more than the other. It also has to do with molecular symmetry and the amount of polar bonds in the compound. Non-polar bonds do not have a dipole interaction or moment. For example, H-CL: the H has a partial positive charge and the Cl has a partial negative charge, and so the dipole moment will look like a long arrow with a plus sign on the end, in which the arrow is pointing toward to more electronegative atom, the Cl. (H +----------> Cl )
p+ p-

#2. all compounds have intermolecular forces known as London Dispersion forces or Van deer Waals forces.

#3. For H bonding always remember "hydrogen bonding is F-O-N". Any Florine, Nitrogen, or Oxygen with a free H attached to it has the ability to hydrogen bond.

Hope that is right and helps..!
 
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Oct 22, 2014
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Yes this helps and that makes perfect sense. Can you explain to me why BrF would be a dipole dipole. There are both partially negative because there on the right side non-metal.... but according to my book it is a dipole. I thought one element has to be partially negative and the other partially positive.
 

csx

May 8, 2013
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Yes this helps and that makes perfect sense. Can you explain to me why BrF would be a dipole dipole. There are both partially negative because there on the right side non-metal.... but according to my book it is a dipole. I thought one element has to be partially negative and the other partially positive.
b/c Br's like yo dawg, you talkin to my girl? Imma smack you. But F is too pimpin so he steals all dat negativity, nom sayin?
 
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Jul 31, 2014
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Also, the intermolecular forces go H-bond> dipole dipole > London Dispersion. I don't know how much detail your test will require but all H bonds have dipole dipole and London dispersion and all dipole have London dispersion BUT we go by whatever the highest intermolecular force so if it's H-bond then instead of saying it's also dipole dipole, we can say it's just H-bond even though it also has dipole dipole.
 
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