Ionic character [ENDORSED]

[Artin Allahverdian 2H]

Why is CF4 more ionic than CH4? To me it seems that the electronegativity difference is more between C and H than between C and F just because H is farther from C than F is. Is there something else that I didn’t put into account?

[Maya_Peterson1C]

If you look up the electronegativity values of H, C, and F, they are 2.1, 2.5, and 4.0 respectively. So, the electronegativity values for Carbon and Hydrogen are a lot closer than the value for Fluorine. Just because they appear closer on the periodic table doesn't necessarily mean their values are closer.

[mahika_nayak_3L]

Fluorine is much more electronegative than Hydrogen is because Fluorine has a greater electron affinity (increases from left to right and down to up) and a higher ionization energy (energy needed to remove the most loosely attached electron). Because the electronegativity of Fluorine is greater compared to Hydrogen, there is also a greater difference between this electronegativity value and that of Carbon. Basically, the Fluorine atoms have a stronger hold on the shared electrons as compared to the hold that Hydrogen has, so the covalent bonds of CF4 exhibit more ionic character.

[Bingcui Guo]

You can see by calculating the difference of electronic affinity. C-F is larger than C-H

[Christopher Wendland 4F]

F is way more electronegative than C and H is only a bit less electronegative than C so the difference is greater between C and F

[Artin Allahverdian 2H]

I think for a question like this he would have to give you the electronegativity values just because it is hard to decipher the electronegativity comparisons just by looking at the periodic trends.