Ionic bond: definition in chemistry
Ionic bond: A chemical bond formed by the attraction between oppositely charged ions, usually after a metal atom transfers electrons to a nonmetal atom.
In forming sodium chloride, each sodium atom gives one electron to a chlorine atom, producing Na⁺ and Cl⁻ ions that attract one another in every direction. The ions pack into a crystal lattice rather than forming separate molecules. Ionic compounds therefore tend to have high melting points, are brittle and conduct electricity when melted or dissolved in water, but not as solids.
Examples
- Sodium chloride (NaCl) — Na⁺ and Cl⁻ ions
- Magnesium oxide (MgO) — Mg²⁺ and O²⁻ ions
- Calcium fluoride (CaF₂) — one Ca²⁺ for every two F⁻
- Potassium iodide (KI) — added to table salt to make iodized salt
On the periodic table
Ionic bonds form most readily between metals at the far left of the table and nonmetals at the far right, where the difference in electronegativity is largest.