Definition · Plain-language
Chemical bond
A chemical bond is a lasting force of attraction that holds atoms together in molecules, compounds and other structures.
The step most authors miss
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Why atoms bond
Atoms bond because the joined arrangement is more stable, with lower energy, than the atoms standing alone. The driving force is the electrons in the outermost shell: most atoms become stable when that shell is full, often with eight electrons, the octet rule. By bonding, atoms gain, lose or share electrons to reach this stable configuration. Energy is released when a stable bond forms, and the same amount of energy must be supplied to break it again — which is why bonds hold matter together.
The main types of bond
Chemical bonds come in three principal types, distinguished by what happens to the electrons. In an ionic bond, electrons are transferred from one atom to another, creating oppositely charged ions that attract — typically between a metal and a non-metal. In a covalent bond, atoms share pairs of electrons, typically between non-metals, forming molecules. In a metallic bond, metal atoms pool their outer electrons into a shared "sea" of delocalised electrons that holds the positive metal ions together, explaining why metals conduct and are malleable.
Strong bonds and weaker forces
The three main bonds are strong, intramolecular bonds — the forces within a molecule or compound. There are also weaker attractions between molecules, called intermolecular forces, such as hydrogen bonds and van der Waals forces. These are not full chemical bonds but they matter enormously: hydrogen bonding between water molecules gives water its high boiling point and surface tension. Distinguishing strong bonds within molecules from weaker forces between them helps explain why substances melt, boil and dissolve as they do.
Key facts
At a glance
- Definition: a lasting attraction that holds atoms together
- Why it forms: the bonded state is more stable (lower energy)
- Driven by: electrons completing a stable outer shell (octet rule)
- Three main types: ionic, covalent and metallic
- Ionic vs covalent: transfer of electrons vs sharing of electrons
- Weaker forces: intermolecular forces (e.g. hydrogen bonds) between molecules
Common misconceptions
What people often get wrong
Often heard: A chemical bond is a physical piece of material joining atoms.
Actually: A bond is a force of attraction arising from how atoms’ electrons interact, not a tangible link. It holds atoms together through electrostatic forces, not a physical thread.
Often heard: There is only one kind of chemical bond.
Actually: There are three main types — ionic, covalent and metallic — defined by whether electrons are transferred, shared, or pooled. Each gives substances different properties.
Often heard: Hydrogen bonds and van der Waals forces are the same as covalent bonds.
Actually: They are weaker intermolecular forces between molecules, not full chemical bonds within them. They are much weaker than ionic, covalent or metallic bonds, though still important.
