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How are single bonds, double bonds, and triple bonds shown in structural formulas?

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Diagram showing four types of crystal bonding: ionic bonding with sodium and chlorine ions, covalent bonding with carbon atoms sharing electrons, metallic bonding with iron ions surrounded by free electrons, and molecular bonding with hydrogen molecules held by weak electrical attraction. — chemical bonding Different types of bonding in crystals.

In structural formulas, covalent bonds are represented by lines connecting the chemical symbols of atoms, with the number of lines indicating the type of bond:12

Single bonds are represented by a single line (—) between two atoms, indicating the sharing of one pair of electrons.32
Double bonds are represented by two parallel lines (=) between two atoms, indicating the sharing of two pairs of electrons.245
Triple bonds are represented by three parallel lines (≡) between two atoms, indicating the sharing of three pairs of electrons.25

These representations allow chemists to visualize the bonding arrangement within a molecule, which is essential for understanding the structure and properties of both organic and inorganic compounds.12