Determine the electron geometry (eg) and molecular geometry (mg) of ICl3.
a
eg = trigonal bipyramidal, mg = T-shape
b
eg = trigonal bipyramidal, mg = bent
c
eg = tetrahedral, mg = trigonal pyramidal
d
eg = trigonal planar, mg = trigonal planar
e
eg = trigonal planar, mg = tetrahedral
The correct answer and explanation is :
The correct answer is:
a) eg = trigonal bipyramidal, mg = T-shape
Explanation:
Iodine trichloride (ICl₃) consists of an iodine (I) atom bonded to three chlorine (Cl) atoms. To determine its electron geometry (EG) and molecular geometry (MG), we follow these steps:
1. Valence Electrons Calculation:
- Iodine (I) has 7 valence electrons.
- Each Chlorine (Cl) has 7 valence electrons.
- Total electrons from ICl₃:
- Iodine: 7
- Chlorine (3 × 7) = 21
- Total: 28 valence electrons
2. Lewis Structure and Electron Regions:
- Iodine is the central atom.
- It forms three single bonds with three chlorine atoms.
- Iodine has two lone pairs of electrons.
- This gives a total of five electron regions around iodine (3 bonding pairs + 2 lone pairs).
3. Electron Geometry (EG):
- A molecule with five electron regions follows the trigonal bipyramidal electron geometry.
- This is because the VSEPR (Valence Shell Electron Pair Repulsion) Theory states that electron domains arrange themselves to minimize repulsion.
4. Molecular Geometry (MG):
- The presence of two lone pairs affects the molecular shape.
- The ideal trigonal bipyramidal structure has five positions:
- Two axial positions (above and below the central atom)
- Three equatorial positions (around the middle plane)
- Lone pairs preferentially occupy equatorial positions to minimize repulsion.
- This leaves the three chlorine atoms in a T-shape molecular geometry.
5. Final Answer:
- Electron Geometry (EG) = Trigonal Bipyramidal
- Molecular Geometry (MG) = T-shape
Thus, the correct answer is (a) eg = trigonal bipyramidal, mg = T-shape.