Hydrogen Bonding

[ryanhon2H]

I understand that hydrogen bonding occurs between hydrogen and N, O, F, but I'm confused why the hydrogen atoms on a molecule aren't counted as being able to form hydrogen bonds. Can't those hydrogen form hydrogen bonds with N, O, or F on another molecule?

For example, a terminal oxygen atom is counted as being able to form a hydrogen bond, but then wouldn't it have to form with a hydrogen on another molecule? So shouldn't that hydrogen on the other molecule be counted as being able to form a hydrogen bond?

[Jessica Castro 2H]

It depends whether or not a hydrogen can form a hydrogen bond. For hydrogens, they must be partially positive to form a hydrogen bond (with N, O, or F). For example, the hydrogens in methane (CH4) have no partial charge. Therefore, they can't form hydrogen bonds.

Since oxygen is a very electronegative atom, it is more likely for oxygen to have a partial negative charge, allowing it to form hydrogen bonds. However, NOT ALL OXYGENS are partially negative.

I hope this answers your question.

[Chem_Mod]

If the hydrogen is covalently bound to F,O,N then it can form a hydrogen bond. A hydrogen on CH4 for example cannot be involved in hydrogen bonding because it is NOT covalently bound to a F,O,N, it is covalently bound to a C

[Kathryn Wilhem 1I]

In hydrogen bonding, the N, O, and F on one molecule form a bond with the H on another molecule, so there needs to be an H bonded to N, O, or F for the molecule to have hydrogen bonding IMF's. For example, in a molecule with an O-H bond, it is polar, so when another O-H bond nearby will have its H that is loosely bonded attracted to the O in the other O-H bond. This is what makes the H bond. You have to remember that IMF's are between molecules that are all the same, and that the H doesn't bond to an H, it bonds with the N, O, or F on another molecule.

[Bella Martin]

So if we're given a CH4 atom and are asked to list the bonding that could occur with a molecule of the same type, what would we say? since its nonpolar, what would the other bondings be besides london dispersion?

[Chris Charton 1B]

CH4 would only have London. This is why it has a low boiling point