Coordinate covalent bond

 

Coordinate covalent bond

Definition

            The bond which is formed by complete transfer of electron pair from one atom to another is known as coordinate covalent bond. Another name of this bond is dative covalent bond or dipolar bond. In this bond both electron came from the same atom.

            This bond is usually formed between ligands and metal during the chemical reaction. Similarly as with any covalent bond, the coordinate covalent bond in after bond formation, reallocate electrons to fulfil the octet rule, which expresses that every particle will lose, gain, or share electrons to have a full valence of eight electrons in its external shell. Hydrogen is a typical exemption for the octet rule, and rather follow the duplet rule because it just has one 1s orbital and its external valence is full when it has two electrons.

Characteristics of Coordinate covalent bond

1.      The atom which share the electron pair in known as donar.

2.      The atom or molecule which accepts the electron is known as accepter or electron deficient.

3.      This bond is always formed between different atoms.

4.      This bond is always formed between electrofile and nucleofile.

5.      The coordinate covalent bond formed due to Lewis theory of bonding.

6.      This bond is always represented by arrow which is pointed from donor to accepter atom.

7.       The compound formed by coordinated covalent bond has low boiling and melting point as compared to ionic compounds but has high melting and boiling point as compared to covalent compounds.

8.       Some compound show the property of isomerism.

9.      Sharing of electrons happens in a distinct way, subsequently, this bond is a directional bond.

10.  This bond is considered as weaker bond then ionic bond.

11.  These compounds normally exist as liquids and gases.

Examples of coordinate compounds

Formation of Ammonium ion

            The nitrogen atom in Ammonia gives its electron pair to the void orbital of H+ particle accordingly nitrogen is giver, H+ is acceptor and a co-ordinate bond is formed.

Ammonium ion

Bond between boron trifluride and ammonia.

            Boron trifluoride is a compound that doesn't have a noble gas structure around the boron particle. The boron just has three sets of electrons in its outermost shell after reaction with chlorine, while there would be space for four sets. BF₃ is depicted as being electron insufficient. The lone pair on the nitrogen of ammonia gas  can be utilized to fulfil that insufficiency, and a compound is formed by coordinate covalent bond. In this bond electrons are shared by nitrogen atom only.

ammonia

boron trifluride

coordinate covalent bond

Formation of hydronium ion

            At the point when hydrogen chloride (HCl) gas breaks down in water to make hydrochloric acid (HCl aq.), an coordinate covalent bond is framed in the hydronium ion. The hydrogen (H) core is moved to the water (H2O) atom, which has a free lone pair of electrons to frame hydronium. Along these lines, H doesn't contribute any electrons to the bond.

hydronium ion

Coordinate covalent bond in carbon monoxide

            Carbon (C) has four electrons in its valence shell, and oxygen (O) has six. Both carbon and oxygen share their two electrons. While the octet rule is happy with oxygen, there is as yet a shortage of two electrons on the carbon. Along these lines, oxygen imparts its two electrons to carbon to make a new coordinate covalent bond, along with  the two ordinary covalent bonds.

formation of CO

Difference between covalent bond and coordinate covalent bond

            In a typical covalent bond, two atoms are held together by sharing a couple of electrons. One electron in this pair comes from one molecule, and the other has a place with the other particle. In a dative covalent bond, we actually have a couple of electrons divided among two molecules but shared by only one atom, other atom has ability to accept electron pair.

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