Bond angle

A bond angle is the angle between two bonds that share an atom. It describes molecular geometry and is commonly measured in degrees.

Valence-shell electron-pair repulsion theory: A model that predicts molecular shapes by treating regions of valence electrons as mutually repelling. Its repulsion rules explain how lone pairs and bonding pairs shift angles around a central atom.
Chemical bond: An attractive interaction that holds atoms or ions together in a chemical substance. A bond angle is defined by two chemical bonds meeting at a shared atom.
Water molecule: A molecule consisting of one oxygen atom bonded to two hydrogen atoms. Its H–O–H angle is about 104.5°, narrowed by oxygen's two lone pairs.
Bond length: The distance between the nuclei of two bonded atoms. Bond length measures separation, whereas bond angle measures direction between bonds.
Molecular orbital theory: A theory that describes molecular electrons as occupying orbitals spread over a molecule. Its orbital picture offers a deeper account of bonding directions and molecular geometry.
Molecular geometry: The three-dimensional arrangement of atoms in a molecule. Bond angles are one of the measurements used to specify molecular geometry.
Ammonia: A nitrogen hydride with the formula NH₃ and a trigonal-pyramidal molecular shape. Its H–N–H angles are about 107°, smaller than the tetrahedral ideal.
Dihedral angle: The angle between two planes defined by four atoms in a molecular structure. Unlike a bond angle, it describes rotation around a bond across four atoms.
Hybridization: A model that combines atomic orbitals into directed hybrid orbitals used to describe bonding. Hybrid orbital directions help account for familiar angles such as 109.5°.
Covalent bond: A chemical bond formed when atoms share one or more pairs of electrons. Most textbook bond angles describe directions of covalent bonds.

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