What is a defining characteristic of ionic bonds?

The defining characteristic of ionic bonds is that they are formed by electron transfer. In an ionic bond, one atom donates one or more of its electrons to another atom. This typically occurs between a metal and a non-metal. The metal, which has a relatively low electronegativity, loses electrons and becomes a positively charged ion (cation), while the non-metal, which has a higher electronegativity, gains those electrons and becomes a negatively charged ion (anion). The electrostatic attraction between these opposing charges holds the ions together, resulting in the formation of an ionic compound.

This process of electron transfer is fundamental to the formation of ionic bonds and distinguishes them from covalent bonds, where atoms share electrons rather than transferring them. Understanding this key characteristic allows for better comprehension of how ionic compounds interact and behave in different environments.