Question

The maximum number of lone pairs of electron on the central atom from the following species is ___________
ClO₃^– , XeF₄, SF₄ and I₃^–

Answer 1

Correct Answer: 3

Analysis of Each Species:

1. \( \text{ClO}_3^- \) (Chlorate ion):
   • Chlorine (\( \text{Cl} \)) is the central atom with 7 valence electrons.
   • Each oxygen (\( \text{O} \)) contributes 6 valence electrons, and the negative charge adds 1 more electron.
   • Total valence electrons: \( 7 + (3 \times 6) + 1 = 26 \).
     
   • Lewis structure: The central \( \text{Cl} \) atom has 1 lone pair.
2. \( \text{XeF}_4 \) (Xenon tetrafluoride):
   • Xenon (\( \text{Xe} \)) is the central atom with 8 valence electrons.
   • Each fluorine (\( \text{F} \)) contributes 7 valence electrons.
   • Total valence electrons: \( 8 + (4 \times 7) = 36 \).
     
   • Lewis structure: The central \( \text{Xe} \) atom has 2 lone pairs.
3. \( \text{SF}_4 \) (Sulfur tetrafluoride):
   • Sulfur (\( \text{S} \)) is the central atom with 6 valence electrons.
   • Each fluorine (\( \text{F} \)) contributes 7 valence electrons.
   • Total valence electrons: \( 6 + (4 \times 7) = 34 \).
     
   • Lewis structure: The central \( \text{S} \) atom has 1 lone pair.
4. \( \text{I}_3^- \) (Triiodide ion):
   • Iodine (\( \text{I} \)) is the central atom with 7 valence electrons.
   • Each other iodine atom contributes 7 valence electrons, and the negative charge adds 1 more electron.
   • Total valence electrons: \( 7 + 7 + 7 + 1 = 22 \).
     
   • Lewis structure: The central \( \text{I} \) atom has 3 lone pairs.

Final Answer:

The maximum number of lone pairs on the central atom is 3 (in \( \text{I}_3^- \)).