What do two ions form when they combine?

When two ions combine, they typically form an ionic compound. This occurs when one ion, often a metal, donates an electron to another ion, usually a non-metal, resulting in the formation of charged particles (cations and anions). These oppositely charged ions attract each other due to electrostatic forces, leading to the creation of a stable ionic compound.

Ionic compounds are characterized by their crystalline structures, high melting and boiling points, and the ability to conduct electricity when dissolved in water or molten. The term "ionic bond" refers specifically to the force that holds the ions together, but it is the arrangement of those ions in a lattice that results in an ionic compound.

In contrast, options like a molecular compound refer to different types of chemical bonding (typically covalent), while a single atom cannot be formed from two ions combining, as both ions inherently possess charge and structure. Therefore, the formation of an ionic compound is the most accurate description of what happens when two ions come together.