Lewis structure

A diagram of a molecule or polyatomic ion that represents atoms, covalent bonds, and valence electrons as dots and lines.

Valence electron: An electron in an atom’s outermost shell that can participate in chemical bonding. Lewis structures track these electrons to account for bonds and lone pairs.
Covalent bond: A chemical bond formed when atoms share one or more pairs of electrons. Each line between atoms represents a shared pair in this notation.
VSEPR theory: A model that predicts molecular geometry from repulsions among electron domains around a central atom. Bonding and lone-pair domains in a Lewis structure feed its geometry predictions.
Structural formula: A chemical notation that shows how atoms in a molecule are connected, often using lines for bonds. It emphasizes connectivity and may omit the lone pairs shown in Lewis diagrams.
Octet rule: A chemical rule of thumb that atoms tend to gain, lose, or share electrons to reach eight valence electrons. It guides the usual placement of bonds and lone pairs around many atoms.
Lone pair: A pair of valence electrons localized on one atom and not shared in a covalent bond. Dots around atoms distinguish nonbonding electrons from shared pairs.
Molecular polarity: The uneven distribution of electric charge across a molecule, producing a net dipole or local bond dipoles. Bond placement and molecular shape help determine whether bond dipoles cancel.
Skeletal formula: An organic chemistry notation that represents carbon frameworks with line segments and omits most carbon and hydrogen labels. It compresses molecular connectivity rather than displaying every valence electron.
Formal charge: A bookkeeping charge assigned to an atom by dividing bonding electrons equally between bonded atoms. It helps compare candidate structures when several arrangements satisfy electron counts.
Bond order: A measure of the number of electron-pair bonds between two atoms. Single, double, and triple lines encode different bond orders.

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