A dative or coordinate bond is a covalent bond in which both of the shared electrons are supplied by the same atom, as in the ammonium ion and the hydronium ion.
A dative bond, also called a coordinate bond, is a covalent bond in which both of the shared electrons are supplied by the same atom. Malay: ikatan datif (koordinat) · Chinese: 配位键.
In an ordinary covalent bond, each atom contributes one electron to the shared pair. In a dative bond the two atoms still share a pair of electrons, so it is still a covalent bond, but one atom donates both electrons while the other simply accepts the pair into an empty space. The donor must have a lone pair to give, and the acceptor must have an empty orbital to receive it. Once formed, a dative bond is identical in strength and length to any other covalent bond; it is only its origin that differs.
Example. The ammonium ion, NH4+, forms when an ammonia molecule, NH3, uses its lone pair to bond to a hydrogen ion, H+, which has no electrons of its own. All four N–H bonds are then the same, even though one began as a dative bond. In the same way the hydronium ion, H3O+, forms when a water molecule donates a lone pair to an H+ ion.
Confusion to avoid. Do not think a dative bond is a different type of bond from covalent, it is a covalent bond, just one where both electrons come from a single atom. In a diagram it is often shown by an arrow pointing from the donor to the acceptor, rather than the usual line or shared dot-and-cross.
The dative bond extends the covalent idea in this chapter and explains how ions such as NH4+ and H3O+ form, a point tested in structure questions in SPM Chemistry.
Want a teacher to make this click?
We teach SPM Chemistry one to one, so your child understands it and scores it.
from RM50/hr · One-hour paid trial · Same-day reply