Question

Circle all hydrogen bond donors in blue and all hydrogen bond acceptors in red.

A) Oxygen, Nitrogen, Fluorine, Chlorine
B) Sodium, Magnesium, Aluminum, Silicon
C) Carbon, Hydrogen, Sulfur, Phosphorus
D) Nitrogen, Carbon, Silicon, Sodium

Answer 1

Hydrogen bonding occurs only with nitrogen, oxygen, or fluorine bonded to hydrogen. These elements can be electron donors due to the exposed hydrogen nucleus and acceptors because of their lone pairs of electrons. An example of a molecule with hydrogen bonding capabilities is water.

Step-by-step explanation:

Hydrogen bonding is a specific type of intermolecular force that occurs in molecules where hydrogen is covalently bonded to nitrogen, oxygen, or fluorine. These elements are highly electronegative, meaning they attract electrons more strongly than hydrogen and create a dipole within the molecule. This results in a partially exposed hydrogen nucleus that can act as a hydrogen bond donor.

For a molecule to act as a hydrogen bond acceptor, it must have lone pairs of electrons. Nitrogen, oxygen, and fluorine not only act as hydrogen bond donors when bonded to hydrogen but also act as acceptors due to their lone pairs. A classic example is water, H2O, where the oxygen has two lone pairs and can form hydrogen bonds with other hydrogen atoms that are covalently bonded to other electronegative elements. In contrast, elements such as sodium and carbon do not typically participate in hydrogen bonding this way.

A substance like water that is both a donor and acceptor can demonstrate hydrogen bonding, for instance, H2O···H2O, where the dots represent the hydrogen bond.