Video Transcript
Which of the following diagrams correctly shows the hydrogen bonding between two molecules of HF?
Hydrogen bonding is a special type of dipole–dipole interaction. It exists between a hydrogen atom on one molecule and a lone pair on a strongly electronegative atom in another molecule. In this case, the strongly electronegative atom is fluorine. As fluorine is more electronegative than hydrogen, the fluorine atom will attract the electron density in the hydrogen fluoride molecule. This results in a partial negative charge on the fluorine and a partial positive charge on the hydrogen. We see the same partial charges in another molecule of hydrogen fluoride.
The positively charged hydrogen atom in one molecule will be attracted to the negatively charged fluorine atom in the other molecule. This attraction is the hydrogen bond. Notice that we represent the hydrogen bond with a dotted line, not an arrow, like we see in answer choice (B). Looking through our answer choices, the only one that has the charges in the correct positions is answer choice (A). So, the only diagram that correctly shows the hydrogen bonding between two molecules of hydrogen fluoride is (A).
