# In terms of electronegativity, why is a "C"="O" bond in "CO"_2 more polar than the "F"-"F" bond in "F"_2?

Dec 31, 2016

See explanation.

#### Explanation:

The electronegativity difference $\left(\Delta \text{EN}\right)$ between two bonded atoms determines the bond character. A $\Delta \text{EN}$$\le 0.4$ is a nonpolar covalent bond. A $\Delta \text{EN}$$> 0.4 < 1.7$ is considered a polar covalent bond. A $\Delta \text{EN}$$\ge 2.0$ is ionic. $\Delta \text{EN}$$> 1.6 < 2.0$ is polar covalent if a nonmetal is bonded to another nonmetal, and ionic if a metal is bonded to a nonmetal.

The $\text{EN}$ of carbon is 2.55. The $\text{EN}$ of oxygen is 3.04. The $\Delta \text{EN}$$= 3.04 - 2.55 = 0.49$, which means the C=O bond is mostly nonpolar with a slight polar character.

The $\text{EN}$ of fluorine is 3.98. The $\Delta \text{EN}$ of the F-F bond is $3.98 - 3.98 = 0$. The F-F bond is completely nonpolar covalent.

Refer to the following website for an electronegativity chart.
https://en.wikipedia.org/wiki/Electronegativity