Bonding Pair
A pair of electrons shared between two atoms and responsible for holding them together.
Unit
Dimensionless
In depth
Each bonding pair is attracted by two nuclei, which concentrates it in the internuclear region and makes it occupy less angular space than a lone pair. Counting bonding versus lone pairs around a central atom is the entire input required by VSEPR theory to predict a molecule's shape.
Examples in the real world
Methane has four bonding pairs and no lone pairs, giving a perfect tetrahedron with 109.5° angles.