Electrostatic attraction between oppositely charged ions formed by electron transfer, typically metal to nonmetal.
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An ionic bond forms when one atom transfers one or more electrons to another, usually from a metal with low ionization energy to a nonmetal with high electron affinity. The resulting cations and anions attract each other through Coulomb's law, F = k q1 q2 / r squared, and this attraction acts equally in all directions. Rather than forming discrete molecules, ionic compounds pack into extended lattices in which each ion is surrounded by ions of opposite charge. The strength of the bond increases with ion charge and decreases as the ions become larger. The energy needed to form the ions is repaid by the large lattice energy released when the solid forms.
Key ideas: Predict ionic character from position: metals from groups 1 and 2 with nonmetals from groups 16 and 17. Write formulas by balancing charges so the net charge is zero, for example Al3+ with O2- gives Al2O3. Coulomb energy scales as q1 q2 divided by r, so doubling both charges roughly quadruples the attraction.
Common mistakes and connections: Students often draw an ionic compound as a molecule with a single bond or speak of a NaCl molecule, but only the formula unit exists. Another error is thinking one particular Na belongs to one particular Cl. Connects to lattice energy, Born-Haber cycles, ionic radii and Fajans' rules.
Sodium gives up an electron to chlorine, and the resulting Na+ and Cl- ions pack in a cubic lattice held by electrostatic attraction in all directions. The interactive lesson shows this as a live animation or chart.
Sodium transfers one electron to chlorine, forming Na+ and Cl- ions that pack into a 1:1 rock-salt lattice.
Electrostatic attraction between oppositely charged ions formed by electron transfer, typically metal to nonmetal.
Ionic Bond is a beginner topic in Bonding & Molecular Structure. It needs no earlier chemistry lessons and is a good starting point.
Study these earlier topics in Bonding & Molecular Structure first: Chemical Bond, Octet Rule, Duet Rule.
The next topics in Bonding & Molecular Structure are Covalent Bond and Metallic Bond.
Yes. The interactive lesson includes a self-check question on Ionic Bond, and the Bonding & Molecular Structure quiz draws on every topic in this area.
Ionic Bond is topic 4 of 104 in Bonding & Molecular Structure.