Question

In the structure of ClF₃ , the number of lone pairs of electrons on central atom ‘Cl’ is

• A. one
• B. four
• C. two
• D. three

Answer 1

The Correct Option is C

To determine the number of lone pairs of electrons on the central atom in ClF₃, we first need to understand the electron configuration and the geometry of the molecule.

1. Valence Electrons: Chlorine (Cl) is the central atom in ClF₃. The valence electrons for chlorine are 7 (since it belongs to Group 17 of the periodic table). Each fluorine (F) atom contributes 7 valence electrons, but since Cl only bonds with them, we only consider Cl's contribution initially.
2. Total Valence Electrons Count: Cl has 7 valence electrons. Adding 3 F atoms means we have a total of 3 \times 7 = 21. However, in the molecule ClF₃, each F shares 1 e^- in a bond, consuming 6 of Cl's e^-, leaving:
   • 7 (Cl) + 3 (bond pairs) = 10 electrons in total for Cl's bonding mechanism.
   • This leaves Cl with 10 - 6 = 4 non-bonded electrons, which equate to 2 lone pairs.
3. Molecular Geometry: ClF₃ exhibits a T-shaped molecular geometry due to the lone pairs. This structure can be attributed to the sp³d hybridization, promoting 3 bond pairs and 2 lone pairs arrangement (Trigonal Bipyramidal geometry with 2 equatorial lone pairs).
4. Conclusion: The number of lone pairs of electrons on the central chlorine atom is therefore 2.

The correct answer is two, which corresponds to the lone pairs on the central atom 'Cl' in ClF₃.