Hydrogen Bonding

[TiffanyBrownfield 2I]

On a few of the Sapling questions, it mentioned that hydrogen bonding can not occur when the hydrogen atom is bonded to a carbon atom. It can only occur when hydrogen is bonded to either oxygen, fluorine, or nitrogen. I think he went over this in one of his lectures, but I'm still not entirely sure why this is?

[Ivan Chen 2H]

The electronegativity difference between carbon and hydrogen isn't significant enough to create a dipole compared to something like oxygen and hydrogen.

[MichaelRaad_1F]

This is because Carbon is not as electronegative as Nitrogen, Oxygen, and Fluorine

[Courtney Situ 2B]

Hi!

So hydrogen bonds have to include a N, O, F molecule b/c these atoms are extremely electronegative, meaning that in a bond with hydrogen, they will hog the electrons. This is why the bond becomes polar, and partial charges form on the atoms. These partial charges are the ones that cause H bonds to form, as H bonds form between different molecules with similar polar bonds.

Note that the difference in electronegativity is key to determining the polarity of the bond. In your case with carbon, carbon and hydrogen do not have a big enough difference in electronegativity to attain the polar bond and partial charges. Therefore, the H's in other molecules will not be attracted to the (nonexistent) partial charges, and there will not be an H bond.

Hope that helps!

[Sera Aintablian 2E]

I believe that hydrocarbons (C-H bonds) do not have a large enough electronegativity difference to form hydrogen bonds. The other atoms (N,O,F) are electronegative enough to form h-bonds. I think C-H bonds only occur when carbon is bound to electronegative atoms.

[Bai Rong Lin 2K]

On a few of the Sapling questions, it mentioned that hydrogen bonding can not occur when the hydrogen atom is bonded to a carbon atom. It can only occur when hydrogen is bonded to either oxygen, fluorine, or nitrogen. I think he went over this in one of his lectures, but I'm still not entirely sure why this is?

It has to do with the elements' electronegativity and differences between oxygen fluorine and nitrogen.

[IshanModiDis2L]

Hydrogen Bonding only works for certain elements (Nitrogen, Oxygen, Fluorine) because those elements have a strong/noticeable amount of electronegativity difference to develop attraction and thus form hydrogen bonds. Hydrocarbons would only happen in certain instances as described above.

[Jacob Schwarz-Discussion 3I]

This is because it needs to bond to something with a higher electronegativity rating like oxygen, nitrogen, or fluorine

[Mehreen 3I]

Hydrogen bonds are the attraction between a hydrogen atom and an oxygen, nitrogen, or fluorine atom (the most electronegative elements).

[Elizabeth Kaplan 3I]

Hi! This is because the electronegativity difference needs to be large enough for the hydrogen to become partially positive, and thus attract another N, O, or F atoms from another molecule.
Hope this helps!

[Joshua Swift]

Hydrogen bonding only occurs in atoms containing Nitrogen, Oxygen, and Flourine.

[Gabriel Nitro 1E]

Hi,

This is because since the electronegativities of nitrogen (N), oxygen (O), and fluorine (F) are so large in magnitude, they are often singled out from the typical dipole-dipole classification when covalently bonded to hydrogen as a hydrogen bond. However, because carbon's (C) electronegativity isn't as large, the difference is not sufficient enough to constitute a hydrogen bond.

Hope this helps! :)

[sophie esherick 3H]

Hydrogen bonding only occurs when an H bonded to an electronegative atom (N, O and F) interacts with an available lone pair on a neighboring electronegative atom (N, F or O again). Carbon isn't electronegative enough to have a partial negative charge when bonded to H therefore Hydrogen bonding cannot occur if an H is bonded to a C. The atoms that give H a partial positive charge due to their electronegativity difference are N, O and F which is why they can form hydrogen bonds.