Co-Ordinate Covalent Bond Or Dative Covalent Bond

The coordinate covalent bond is also a special type of covalent bond, in which both electrons forming a bond are supplied by one atom only. The atom which supplies the pair of electrons for bond formation is known as "Donor" and the atom which accepts, is known as "Acceptor. An arrow (>) is commonly used to denote the bond, in which the head of an arrow pointing towards acceptor atom. The pair of electrons possessed by donor is called "Lone-pair" of electrons. This type of bond is also called dative covalent bond.


In the formation of ammonium chloride, from ammonia (NH3) and hydrogen chloride (HCl) molecules, the nitrogen (N) atom of ammonia (NH3) acts as donor of an electron pair and hydrogen ion (H+) of hydrogen chloride accept it to form (NH4Cl) as follows.

Another example is provided by the formation of hydronium ion (HO2) from water molecule and hydrogen ion (H+), in which the oxygen atom of water acts as donor and hydrogen ion (H+), as acceptor.

5.6.1 Comparison between Covalent Bond and Co-ordinate Covalent


Covalent bond

1 The covalent bond is formed by the mutual sharing of electrons between atoms.

2. The covalent bond is formed between the similar or dissimilar atoms, when the electrons are mutually shared.

3. Covalent bond may be polar or non-polar

4. Covalent bond is associated with only covalent character because there is no electron transfer.

5. The shared pair of electrons in covalent bond are denoted by short lines e.g. for single pair (-) for double pair (=) and for triple pair of electrons (=).

6. Covalent   compounds   are usually insoluble in water.


Co-ordinate Covalent bond

1. The co-ordinate covalent bond is formed by one sided sharing of electrons.

2. Co-ordinate covalent bond is formed between two unlike atoms, one having an electron pair available for sharing and other must accept that electron pair.

3. Co-ordinate covalent bond is always polar, because it is not formed between like atoms and is also known as co-ionic.

4. Co-ordinate covalent bond is associated with the ionic and covalent character because of partial transfer of electrons.

5. The shared pair of electrons in co-ordinate covalent bond is denoted by an arrow (>).

6. Where as co-ordinate covalent compounds are sparingly soluble in water.


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