Which type of bond involves one atom losing an electron and another gaining an electron?

The correct answer is the ionic bond, which is characterized by the transfer of electrons from one atom to another. In an ionic bond, one atom, typically a metal, loses one or more electrons, becoming a positively charged ion, while the other atom, usually a nonmetal, gains those electrons to become a negatively charged ion. This transfer creates electrostatic attraction between the oppositely charged ions, leading to the formation of the ionic bond.

Covalent bonds involve the sharing of electron pairs between atoms, allowing each to achieve a more stable electron configuration without transferring electrons. Hydrogen bonds are a type of weak attraction between a hydrogen atom, covalently bonded to an electronegative atom, and another electronegative atom. Metallic bonds consist of a lattice of positively charged metal ions surrounded by a 'sea' of delocalized electrons, allowing for conductivity and malleability, but do not involve the transfer of electrons in the way ionic bonds do.