What type of bond is formed when positive and negative ions join?

The type of bond formed when positive and negative ions join is known as an ionic bond. This bond occurs when one atom donates an electron to another atom, resulting in one positively charged ion (cation) and one negatively charged ion (anion). The electrostatic attraction between these oppositely charged ions creates a strong bond, which holds them together in a compound.

Ionic bonds are prevalent in the formation of salts, such as sodium chloride (table salt), which consists of sodium ions and chloride ions. In this case, the sodium atom loses an electron to become positively charged, while the chlorine atom gains an electron to become negatively charged. The resulting attraction between these charged particles stabilizes the compound.

In contrast, covalent bonds involve the sharing of electrons between atoms, hydrogen bonds are a weaker attraction typically found in polar molecules involving hydrogen, and metallic bonds occur between metal atoms that share a "sea of electrons." Each of these other types of bonds has distinct characteristics and is responsible for different properties in materials, but they do not reflect the interaction between positive and negative ions that defines an ionic bond.