Why is the CF bond in CF4 polar covalent? Shouldn’t it be nonpolar like in CH4?

Question

Why is the carbon-fluorine (C-F) bond in carbon tetrafluoride (CF4) considered polar covalent? Shouldn’t it behave like the carbon-hydrogen (C-H) bond in methane (CH4), which is nonpolar?

Macey Langosh MD · Accepted Answer

Partially correct.  When one is talking about the bond itself, it means the difference in electronegativities between the two atoms of the bond.  CH4 is nonpolar because the electronegativity of carbon (2.55) and hydrogen (2.2) are very close.  But, when we're talking about CF4, the electronegativity of fluorine is 4.0, while carbon is 2.55.  This means that fluorine has a huge amount of pull on the electrons from carbon, making the electrons more likely to be around fluorine rather than carbon, producing a polar covalent bond.  BUT, the actual entire molecule of CF4 itself is nonpolar, as is methane.  The reason for that is that every CF polar bond is pointing in a certain angle along a tetrahedral structure typical of CF4 and CH4, in such a way that all the polar bonds cancel in each direction.  If you think of each bond as a vector, the vector sum is equal to zero, so the CF4 MOLECULE is nonpolar, but the INDIVIDUAL CF bonds are polar.  CH4 bonds are simply inherently nonpolar, but both CF4 and CH4 are nonpolar molecules.

Anonymous · Answer

Cf4 Polar

Anonymous · Answer

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Where's your chemistry book, hon? This is a page of answers. hint: double bonds are virtually never polar, symetrical configurations are never polar, mono atomic compounds are never polar, the further apart the elements are (left and right) on the periodic table, the more likely they are to form polar molecules

Anonymous · Answer

Because F is more electronegative then C, so it will pull Carbon's electrons towards itself, now imagine you have the CF4 molecule, each F is pulling on the carbon from each side, so that means that since everything is symmetrical, the pulling cancel each other out

Anonymous · Answer

The bond is a lot more polar because F is a lot more electronegative than C.
The molecule as a whole, however, is still non-polar because the  individual bond dipoles cancel out.

Anonymous · Answer

The electronegativity difference between carbon and fluorine is higher than between carbon and hydrogen. So the bond between C and F is polar.

Jazmin Nader III

Why is the CF bond in CF4 polar covalent? Shouldn’t it be nonpolar like in CH4?

6 Answers

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