what is the molecular geometry around sulfur in SF3+ ?
The correct answer and explanation is :
The molecular geometry around sulfur in the ion ( \text{SF}_3^+ ) is trigonal planar.
Explanation:
To determine the molecular geometry of ( \text{SF}_3^+ ), let’s first consider its structure and electron distribution.
- Lewis Structure:
- Sulfur (S) is in Group 16 of the periodic table, so it has 6 valence electrons.
- Fluorine (F) is in Group 17, so each fluorine atom contributes 7 valence electrons. In the ion ( \text{SF}_3^+ ), the sulfur atom is surrounded by three fluorine atoms and carries a positive charge.
- The positive charge suggests that one of the valence electrons has been lost, leading to only 5 electrons available for bonding.
- Each fluorine atom forms a single bond with sulfur, using one electron from sulfur and one from fluorine. This results in 3 bonding pairs of electrons.
- Electron Domains:
The sulfur atom in ( \text{SF}_3^+ ) has 3 bonding pairs of electrons (one for each ( \text{S-F} ) bond) and no lone pairs because all available electrons are used in bonding. Therefore, there are 3 electron pairs around sulfur. - VSEPR Theory:
According to the Valence Shell Electron Pair Repulsion (VSEPR) theory, when there are 3 electron pairs around the central atom and no lone pairs, the geometry adopts a trigonal planar shape to minimize repulsion between the bonding pairs of electrons. The bond angles in a trigonal planar geometry are 120°.
Final Geometry:
Thus, the molecular geometry around sulfur in ( \text{SF}_3^+ ) is trigonal planar, with the three fluorine atoms arranged at 120° angles around the sulfur atom. The positive charge on the ion is balanced by the bonding structure, and the lack of lone pairs leads to the ideal trigonal planar shape.