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Electronegativity and bond strength?

If a bond is more polar, such as C-F bond, does it necessarily mean that the bond is very strong compared to C-Cl bond?

Is there a correlation between electronegativity and bond strength is what I mean
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Avatar for BJack
BJack
19
Original post by Me14
If a bond is more polar, such as C-F bond, does it necessarily mean that the bond is very strong compared to C-Cl bond?

Is there a correlation between electronegativity and bond strength is what I mean


If there's a greater electronegativity difference, the bond is more polar. This gives an additional electrostatic component to the bonding, making it stronger. I would imagine that there are examples where this fails for whatever reason, but it's good as a general rule. (Indeed, Pauling came up with his electronegativity scale by looking at how heteronuclear bond strengths differed from the expected average of homonuclear bond lengths - i.e. A-B vs (A-A + B-B) - so by that reasoning it's absolutely true.)
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Avatar for myah_94
myah_94
12
Original post by Me14
If a bond is more polar, such as C-F bond, does it necessarily mean that the bond is very strong compared to C-Cl bond?

Is there a correlation between electronegativity and bond strength is what I mean


Yeah there is
Original post by Me14
If a bond is more polar, such as C-F bond, does it necessarily mean that the bond is very strong compared to C-Cl bond?

Is there a correlation between electronegativity and bond strength is what I mean


Difficult to quantify. From a MO point of view, our 'best' simple theory for bonding (covalent), an electronegativity difference weakens bonding. A difference in electronegativity roughly corresponds to a difference in orbital energy and the maximum for covalent bonding is always found (for a given overlap integral) at the energy gap being zero.

Then you need to consider Ionic bonding. For this reason MO theory often underestimates sharply the bond strength of polar bonds. Obviously ionic lattices are strongly bonded but with only weak covalent bonds so they aren't insignificant. With regards to the strength of a C-Cl bond vs a C-F bond, the difference in electronegativity is not the only parameter changing. The orbital energy gap and the overlap integrals are also sharply changing so you're trying to make a comparison while changing many variables.

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