Ionic Bond
The electrostatic attraction between oppositely charged ions formed by the complete transfer of electrons from one atom to another.
Formula / equation
F ∝ q₁q₂ / r²
Unit
kJ/mol
In depth
Ionic bonding is favoured when electronegativity differs by more than about 1.7, typically between a metal and a non-metal. The attraction is non-directional, so ions pack into extended three-dimensional lattices rather than discrete molecules, giving high melting points, brittleness and conductivity when molten or dissolved.
Examples in the real world
Sodium chloride, magnesium oxide (melting at 2852 °C because of its 2+/2− charges) and calcium fluoride.