In this case the leaving group gets a pair of electrons.

Such a group is referred to as an electron pair.

One pair of shared electrons is called a single bond.

Such an arrangement makes electron pairs closer together than they need to be.

Each link is a pair of electrons shared only between those two atoms.

In other words, one pair of electrons is shared.

It places electron pairs 90 degrees from their nearest neighbors.

Two atoms can be bonded by sharing more than one pair of electrons.

This electron pair forms the bond with a proton (H+).

An especially odd quality of the electron pairs is that their members, though coordinated, remain relatively far apart in space.