How does covalent bonding differ from ionic bonding?

The primary difference between ionic and covalent bonding lies in how atoms interact with their valence electrons to achieve stability.12

Ionic Bonding

An ionic bond occurs when one atom permanently transfers one or more valence electrons to another atom. This process creates oppositely charged ions:12
* Cations: The atom that loses electrons becomes positively charged.13
* Anions: The atom that gains electrons becomes negatively charged.13
The resulting bond is the electrostatic attraction between these ions. These compounds typically form between metals and nonmetals and often exist as crystalline solids with high melting points.12

Covalent Bonding

A covalent bond involves the sharing of electron pairs between atoms. Rather than transferring electrons, atoms—typically two nonmetals—share them to complete their valence shells.32
* Sharing: In the simple valence-bond model, electrons are treated as being shared between nuclei.2
* Molecular Orbitals: A more comprehensive view, molecular-orbital theory, describes electrons as being distributed over the atoms in the molecule within specific spatial regions called molecular orbitals.2

While these categories are distinct, they exist on a spectrum; an ionic bond is considered the extreme case of a polar covalent bond where the difference in electronegativity between atoms is very large.1