Class 9

9.3.5 Coordinate Covalent Bond

This is the third lecture from Chapter 3: “Chemical Bonding” in the new Class 9 Chemistry book (Punjab Board – PCTB). It discusses the formation of coordinate covalent bond. The lecture also includes a multiple-choice quiz, short question and long question notes.

MCQs Based Quiz

9.3.5 Coordinate Covalent Bond

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A chemical bond in which shared pair of electrons is donated by only one atom is called:

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A coordinate covalent bond is a chemical bond in which both electrons of a bond pair are shared by a single atom. This chemical bond is represented by:

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In a coordinate covalent bond, the arrow head (⟶) points towards:

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How can we differentiate a coordinate covalent bond from a normal covalent bond?

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What type of chemical bond is formed between water and a proton (H⁺)?

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In a coordinate covalent bond between water and a proton (H+), water acts as:

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In a coordinate covalent bond between water and a proton (H+), the proton (H+) acts as:

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Which of the following chemical species is a result of coordinate covalent bond formation?

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Which of the following chemical species is a result of coordinate covalent bond formation?

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In a hydroxonium ion (H₃O⁺), oxygen atom of water donates a bond pair to a proton (H⁺) to form a coordinate covalent bond. After the formation of the bond, the positive charge of proton ___.

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In a hydroxonium ion (H₃O⁺), oxygen atom of water donates a bond pair to a proton (H⁺) to form a coordinate covalent bond. After the formation of the bond ___.

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In a hydroxonium ion (H₃O⁺):

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During the reaction between ammonia (NH₃) and boron trifluoride (BF₃):

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If the coordinate covalent bond between ammonia (NH₃) and boron trifluoride (BF₃) breaks:

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Short Questions

Q1. Define coordinate covalent bond.

A coordinate covalent bond is type of covalent bond in which shared pair of electrons is donated by only one atom. It is represented by an arrow (⟶) that points from the donor to the acceptor.

Q2. What is meant by donor and acceptor chemical species in a coordinate covalent bond?

A chemical species that donates the shared pair of electrons in a coordinate covalent bond is called a donor, whereas the chemical species that accepts this shared pair of electrons is called the acceptor species.

Water (Donor) and Proton (H+) (Acceptor) - Coordinate Covalent Bond

Q3. How is hydronium (H3O+) formed?

The oxygen atom from a water molecule donates a shared pair of electrons to a proton (H+). This leads to the formation of the hydronium ion (H3O+)

Water (Donor) and Proton (H+) (Acceptor) - Coordinate Covalent Bond

Q4. Can you identify a coordinate covalent bond in a compound?

No, after the formation of a coordinate covalent bond, there remains no difference between a covalent bond and a coordinate covalent bond. So, we cannot differentiate between these two types of bonds.

Q5. What happens to the shared pair of electrons when a coordinate covalent bond breaks?

When a coordinate covalent bond breaks, the shared pair of electrons returns to the donor species.

Q6. What happens to the positive charge of the proton after the formation of a coordinate covalent bond with water?

After the formation of a coordinate covalent bond, the positive charge is spread over the entire hydronium ion (H3O+).

Q7. Draw the pictures of coordinate covalent bond formed between:

(a) BF3 and AlCl3

Chemical Bonding Between AlCl3 and BF3 (Coordinate Covalent Bond)

(b) CH3OCH3 and H+

Chemical Bonding Between Dimethyl Ether and Proton (Coordinate Covalent Bond)

Q8. Which compounds are not able to form coordinate covalent bonds?

Compounds that are unable to donate a shared pair of electrons, or those that cannot accept this shared pair of electrons, are not able to form a coordinate covalent bond.

Descriptive Question

What is a coordinate covalent bond? Explain the formation of hydronium ion (H3O+).

A coordinate covalent bond is type of covalent bond in which shared pair of electrons is donated by only one atom. It is represented by an arrow (⟶) that points from the donor to the acceptor.

A chemical species that donates the shared pair of electrons in a coordinate covalent bond is called a donor, whereas the chemical species that accepts this shared pair of electrons is called the acceptor species.

Formation of Coordinate Covalent Bond in H3O+:

  1. An acid provides a proton (H+) in water. This proton has an empty shell which can accommodate a bond pair.
  2. The oxygen atom in the water molecule shares one of its electron pairs with the proton (H+).
  3. This leads to the formation of coordinate covalent bond between water and the proton, represented by an arrow pointing from water (donor) to proton (acceptor).
  4. After the formation of coordinate covalent bond, the positive charge covers the entire hydronium ion.
  5. We cannot differentiate between a coordinate covalent bond and a covalent bond, because once formed, all three bonds of oxygen behave identically.
  6. However, if the bond breaks, the shared pair of electrons returns to the water molecule (donor).

Water (Donor) and Proton (H+) (Acceptor) - Coordinate Covalent Bond

Explain the reaction between ammonia (NH3) and boron trifluoride (BF3).

The reaction between ammonia and boron trifluoride (BF3) leads to the formation of a coordinate covalent bond:

  1. The boron atom in BF3 has an incomplete outer shell to accept a pair of electrons.
  2. The nitrogen atom in ammonia shares its extra pair of electrons with the boron atom.
  3. This leads in the formation of a coordinate covalent bond between NH3 and BF3, which is indicated by an arrow (⟶), pointing from NH3 (donor) to BF3 (acceptor).
  4. The resulting compound is stable, and the coordinate bond becomes identical to the other covalent bonds in the molecule.
  5. However, if the bond breaks, the shared pair of electrons goes back to the nitrogen atom (donor).

Reaction Between Ammonia (NH3) and Boron Trifluoride (BF3) (Coordinate Covalent Bond)

Draw pictures of coordinate covalent bond formed between following compounds.

(a) NH3 and HCl

Reaction Between Ammonia (NH3) and Hydrogen Chloride (Coordinate Covalent Bond)

(b) C2H5OH and H+

Reaction Between Ethanol and Proton (Coordinate Covalent Bond)

BF3 and AlCl3

Reaction Between Aluminium Trichloride (AlCl3) and Boron Trifluoride (BF3) (Coordinate Covalent Bond)

CH3OCH3 and H+

Reaction Between Dimethyl Ether and Proton - Formation of Hydronium Ion (H3O+)(Coordinate Covalent Bond Formation)