Which element is a hydrogen bond acceptor?

A hydrogen bond acceptor is an electronegative atom that can attract and bond with a hydrogen atom that is covalently bonded to another electronegative atom. Oxygen is a prime example of such an atom. It possesses a partial negative charge due to its high electronegativity, which enables it to attract the hydrogen atom from another molecule, forming a hydrogen bond.

In biological systems, oxygen frequently participates in hydrogen bonding with water molecules, proteins, and nucleic acids, significantly influencing their structures and functions. This characteristic of oxygen is fundamental in many biochemical interactions, such as maintaining the secondary and tertiary structures of proteins and the stability of DNA.

The other elements listed, such as carbon, sodium, and calcium, do not commonly act as hydrogen bond acceptors. Carbon, while it can form covalent bonds, does not have the electronegativity needed to effectively accept hydrogen bonds. Sodium and calcium are metals that typically form ionic bonds and are not involved in hydrogen bonding interactions.