Homework Problem 3.87

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Amanda Hagen 1L
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Joined: Fri Sep 29, 2017 7:04 am

Homework Problem 3.87

Postby Amanda Hagen 1L » Wed Nov 08, 2017 5:17 pm

Can someone please explain why CF4 has the shortest bond out of CF4, CCl4, and CBr4? I understand that it is the strongest because it is the shortest, however, I'm not sure how to determine that it has the shortest bond.

Alex Leve 3F
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Joined: Fri Sep 29, 2017 7:07 am

Re: Homework Problem 3.87

Postby Alex Leve 3F » Wed Nov 08, 2017 5:23 pm

You know the relative lengths of the bonds because you know the relative electronegativities. F is more electronegative than Cl and Br, and therefore it will bring the electrons as close to it as possible, forming a shorter, stronger bond.

aTirumalai-1I
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Re: Homework Problem 3.87

Postby aTirumalai-1I » Wed Nov 08, 2017 5:26 pm

CF4 has the shortest bond because F is the most electronegative among F, Cl, and Br. This basically means that F pulls on its surrounding electrons with more strength than Cl or Br can, making it so that in CF4, the atoms are all very close together (aka short bond lengths).

Emilie Hoffman 1E
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Re: Homework Problem 3.87

Postby Emilie Hoffman 1E » Wed Nov 08, 2017 8:44 pm

Could someone explain in another way because the solution book specifically points that the electronegativity of CF4 would predict a weakest bond for CF4.

Emily Oren 3C
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Re: Homework Problem 3.87

Postby Emily Oren 3C » Wed Nov 08, 2017 10:48 pm

F is the smallest atom among F, Cl, and Br, meaning that the internuclear distance between the fluorine and carbon would be the smallest even while ignoring any effects by the relative electronegativities. This means the F-C bond is the shortest of the three.

Joshua Hughes 1L
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Re: Homework Problem 3.87

Postby Joshua Hughes 1L » Wed Nov 08, 2017 11:55 pm

Wait I'm also am a bit confused on the solutions manual's explanation. I still don't understand why the book would say that "electronegativity and polarity arguments would predict C- F bonds to be the weakest"? To me, the reasoning provided above about F being the most electronegative and being overall a smaller atom makes sense as to why the bonds would be shorter and stronger.


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