BIOCHEMISTRY
POLAR AND NONPOLAR MOLECULES
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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CF4 and CClF3 are molecules with a tetrahedral shape. Which statement is correct?
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Both molecules are polar because of bond symmetry.
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Only CF4 is polar because all four bonds have the same difference in electronegativity.
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Only CClF3 is polar because one of the four bonds has a different electronegativity difference than the other three.
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Both molecules are nonpolar because of bond symmetry.
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Explanation:
Detailed explanation-1: -If we look at the bonds individually, Carbon has an electronegativity of 2.5 and fluorine has an electronegativity of 4.0. The difference of 1.5 says that each C-F bond is very polar, but when put into the structure the symmetry cancels this polarity out and the overall structure is nonpolar.
Detailed explanation-2: -CF4 is non-polar because its structure is tetrahedral with four symmetric C-F bonds.
Detailed explanation-3: -Each “C-F” bond is polar because fluorine is more electronegative. However, the compound itself is not polar because the polar bond vectors exactly cancel out in the tetrahedral geometry.
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