3.8 Co-ordinate Covalent Bond

This topic explains the coordinate covalent bond (also called a dative covalent bond), how it is formed, and examples of molecules that contain this type of bond.

Definition

A coordinate covalent bond is formed when one atom provides both electrons for a covalent bond.

Requirements

• Donor atom: Has a lone pair of electrons.
• Acceptor atom: Has an empty orbital to accept the lone pair.

Examples

• Water (H₂O) has two lone pairs on oxygen.
• One lone pair is donated to H⁺ (which has an empty 1s orbital).
• Result: H₃O⁺ with a dative bond.

• Central oxygen atom has a lone pair.
• It donates the lone pair to a terminal oxygen atom.
• Result: O₃ with a dative bond.

• Oxygen atom has lone pairs.
• Carbon atom has an empty orbital.
• Oxygen donates a lone pair to carbon.
• Result: CO with a dative bond.

Key Point

• Once formed, a coordinate covalent bond is indistinguishable from a normal covalent bond.
• The only difference is how the bond was formed (one atom donated both electrons).

Main Idea

• One atom having a lone pair of electrons.
• The second atom having an unfilled empty orbital to accept the lone pair (an electron-deficient atom/molecule).

Core Concept

In a normal covalent bond, each atom contributes one electron to the shared pair. In a coordinate covalent bond, one atom contributes both electrons. Once formed, the coordinate covalent bond is indistinguishable from a normal covalent bond.

Detailed Explanation

Requirements for Dative Covalent Bonding

• One atom having a lone pair of electrons — the donor atom.
• The second atom having an unfilled empty orbital to accept the lone pair — the acceptor atom (an electron-deficient atom/molecule).

Example 1: Formation of Hydronium Ion (H₃O⁺)

• During the formation of hydronium ion, water containing a lone pair of electrons donates a pair of electrons.
• It forms a dative bond with the electron-deficient hydrogen ion (H⁺).
• The water molecule has two lone pairs on oxygen.
• One lone pair is donated to the H⁺ ion.
• The result is the hydronium ion (H₃O⁺).

H_2O + H^+ \rightarrow H_3O^+

Example 2: Ozone (O₃)

• In the ozone (O₃) molecule, the central oxygen atom donates its electron pair with another oxygen atom.
• It forms a dative bond.
• The central oxygen atom has a lone pair, which it shares with the terminal oxygen atom.

Example 3: Carbon Monoxide (CO)

• Coordinate covalent bond is also present in the carbon monoxide molecule.
• In this molecule, the oxygen atom forms a coordinate covalent bond with the carbon atom.
• Oxygen has lone pairs, and carbon has an empty orbital to accept the lone pair.

Summary of Examples

Important Points

• 1. Coordinate covalent bond = one atom provides both electrons.
• 2. Requirements: Donor with lone pair; acceptor with empty orbital.
• 3. Examples: H₃O⁺, O₃, CO.
• 4. Once formed, it is indistinguishable from a normal covalent bond.
• 5. Also called a dative covalent bond.

Remember

• - Coordinate covalent bond: One atom provides both electrons
• - Requirements: Donor (lone pair) + Acceptor (empty orbital)
• - Examples: H₃O⁺, O₃, CO
• - Also called: Dative covalent bond

Common Mistakes

• 1. Thinking coordinate covalent bonds are different from normal covalent bonds: Once formed, they are indistinguishable.
• 2. Forgetting the requirements: Donor must have a lone pair; acceptor must have an empty orbital.
• 3. Confusing donor and acceptor: The donor provides the electrons; the acceptor receives them.
• 4. Ignoring examples: H₃O⁺, O₃, and CO are important examples.

Quick Revision

• Coordinate covalent bond = one atom provides both electrons.
• Requirements: Donor with lone pair; acceptor with empty orbital.
• Examples: H₃O⁺, O₃, CO.
• Once formed, it is indistinguishable from a normal covalent bond.
• Also called a dative covalent bond.

60-Second Revision

• Coordinate covalent bond: One atom provides both electrons
• Requirements: Donor (lone pair) + Acceptor (empty orbital)
• Examples: H₃O⁺, O₃, CO
• Also called: Dative covalent bond

QUALITY VALIDATION

• Topic: 3.8 Co-ordinate Covalent Bond
• Chapter: 3 (Chemical Bonding)

• Source re-read: PASS
• Source scope followed: PASS
• Knowledge level matched: PASS
• Important concepts covered: PASS
• Definitions checked: PASS
• Equations checked: N/A
• Derivations checked: N/A
• Examples checked: PASS
• Unsupported knowledge added: NO
• Unnecessary repetition: NO
• Notes format maintained: PASS
• Important source content omitted: NO

• Source limitations:
• NONE

NEXT TOPIC