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Homework Problem 3.87

Posted: Wed Nov 08, 2017 5:17 pm
by Amanda Hagen 1L
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.

Re: Homework Problem 3.87

Posted: Wed Nov 08, 2017 5:23 pm
by Alex Leve 3F
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.

Re: Homework Problem 3.87

Posted: Wed Nov 08, 2017 5:26 pm
by aTirumalai-1I
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).

Re: Homework Problem 3.87

Posted: Wed Nov 08, 2017 8:44 pm
by Emilie Hoffman 1E
Could someone explain in another way because the solution book specifically points that the electronegativity of CF4 would predict a weakest bond for CF4.

Re: Homework Problem 3.87

Posted: Wed Nov 08, 2017 10:48 pm
by Emily Oren 3C
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.

Re: Homework Problem 3.87

Posted: Wed Nov 08, 2017 11:55 pm
by Joshua Hughes 1L
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.