What characterizes an ionic bond?

An ionic bond is primarily characterized by the transfer of electrons between atoms, typically occurring between a metal and a non-metal. In this type of bond, an atom with a low ionization energy, usually a metal, loses one or more electrons, while an atom with a high electron affinity, typically a non-metal, gains those electrons. This electron transfer leads to the formation of positively charged cations and negatively charged anions, which are held together by the electrostatic forces of attraction between them.

This fundamental principle underpins the structure and stability of ionic compounds, which tend to have high melting and boiling points, and are often soluble in water. Additionally, the transfer of electrons significantly alters the properties of the involved elements, transforming them into different species that can form a stable lattice structure in the solid state.

The other options describe different types of interactions: sharing electrons characterizes covalent bonds, a hydrogen bond is an attraction between molecules (specifically, involving hydrogen atoms), and the repulsion between negatively charged ions is not a bonding characteristic but rather describes a tendency that would prevent the formation of stable ionic bonds.