relative bond strength as a funciton of polarity

[thebillsfan]

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this is something that i should know, but alas, i'm not sure of. partly its because i read conflicting information on it. anyway...does bond strength increase or decrease with the polarity of the bond? so, is H-F strong than, say, a C-C bond in an alkane? That's all, thanks

 

[ezsanche]

http://www.science.uwaterloo.ca/~cchieh/cact/c120/bondel.html

this site has a list of the bond dissociation energies of several different types of bonds. The higher the dissociation energy the stronger the bond. See if you can see any patterns based on electronegativity.

 

[thebillsfan]

http://www.science.uwaterloo.ca/~cchieh/cact/c120/bondel.html

this site has a list of the bond dissociation energies of several different types of bonds. The higher the dissociation energy the stronger the bond. See if you can see any patterns based on electronegativity.

it seems that the higher polarity, the stronger the bond (although the pattern isnt as clear as i wouldve liked because of diff sizes of atoms). now, i'm trying to understand that intuitively. more polar would mean more electrostatic character--a possible argument in favor of stronger bonds. less polar would mean more equal sharing of electrons--which could also be seen as an argument in favor of stronger bonds. what's the deal?

 

[loveoforganic]

It depends what you're talking about. If you're talking about homolyzing the bond (splitting into radicals), then higher polarity means stronger bond.

 

[thebillsfan]

I guess I'm talking about heating it

 

[minutemen11]

If you think about it, the more polar a bond is the more intermolecular force it has. Therefore, it would require more energy to overcome these forces meaning that the strength of the bond is pretty strong

 

[loveoforganic]

I guess I'm talking about heating it

Huh? The choices are homolytic or heterolytic cleavage! 😛

 

[thebillsfan]

LoO,

wouldn't heating it yield heterolytic?

 

[thebillsfan]

when you were referring to homolytic, i assumed you were talking about light/radicals. now i realize that's sort of stupid b/c radicals can form even from heat. my bad

ANYWAY, the point is, for heterolytic, would a more polar bond be stronger or weaker?

 

[ezsanche]

If you think about it, the more polar a bond is the more intermolecular force it has. Therefore, it would require more energy to overcome these forces meaning that the strength of the bond is pretty strong

I believe he is referring to intramolecular forces not intermolecular forces

 

[thebillsfan]

yeah i'm talking about intra, sorry if that was unclear

 

[loveoforganic]

when you were referring to homolytic, i assumed you were talking about light/radicals. now i realize that's sort of stupid b/c radicals can form even from heat. my bad

ANYWAY, the point is, for heterolytic, would a more polar bond be stronger or weaker?

weaker, I believe

 

[OMTlover]

weaker, I believe

The higher the polarity of the bond, the lower is the bond energy; general trend. Polarized bnds are easier to break. Also, intramolec. forces are always stronger than intermolec. forces

 

[thebillsfan]

The higher the polarity of the bond, the lower is the bond energy; general trend. Polarized bnds are easier to break. Also, intramolec. forces are always stronger than intermolec. forces

that isn't supported by the data from this link

http://www.science.uwaterloo.ca/~cch...20/bondel.html