Transcribed image text: Draw the Lewis dot structure of ICI. Determine the molecular shape of this substance. Make sure to use lines for shared electrons and dots for individual electrons. (3 pts)
Draw the lewis dot structure of ICl3 and determine the molecular shape of this substance. Please make sure to use lines for shared electrons and dots for individual electrons. Thanks!
The Correct Answer and Explanation is:
1. Lewis Dot Structure and Molecular Shape of ICl (Iodine Monochloride)
Lewis Structure of ICl:
.. ..
:Cl — I:
.. ..
- Iodine (I) and Chlorine (Cl) are both halogens, so they each have 7 valence electrons.
- They share one pair of electrons to form a single bond (I—Cl).
- Each atom also has three lone pairs (6 electrons) remaining.
- Total valence electrons: 7 (I) + 7 (Cl) = 14 electrons.
Molecular Shape:
- Linear (only two atoms, bond angle = 180°).
2. Lewis Dot Structure and Molecular Shape of ICl₃ (Iodine Trichloride)
Lewis Structure of ICl₃:
..
:Cl:
|
:Cl—I—Cl:
..
- Iodine has 7 valence electrons.
- Each Cl atom has 7 valence electrons and forms a single bond with iodine.
- Iodine shares 3 of its electrons with 3 chlorine atoms, and has 2 lone pairs left.
- Total valence electrons: 7 (I) + 3×7 (Cl) = 28 electrons.
Electron count around Iodine:
- 3 bonding pairs (shared with Cl) = 6 electrons
- 2 lone pairs = 4 electrons
- Total = 10 electrons → This is acceptable due to iodine’s ability to expand its octet.
Molecular Shape:
- Electron geometry: Trigonal bipyramidal (5 electron groups)
- Molecular geometry: T-shaped (due to 2 lone pairs on equatorial positions)
Explanation
Iodine monochloride (ICl) is a diatomic molecule consisting of iodine and chlorine, both halogens with seven valence electrons. In the Lewis structure, each atom shares one electron to form a single covalent bond, fulfilling the octet rule for both atoms. Each atom also retains three lone pairs. The molecule is linear because there are only two atoms involved, and no central atom geometry needs to be considered. Thus, the molecular shape of ICl is linear with a bond angle of 180°.
In contrast, iodine trichloride (ICl₃) has a more complex structure. Iodine is the central atom bonded to three chlorine atoms. Iodine has seven valence electrons, and when it forms three single bonds with chlorine atoms (one electron each), it uses three of its electrons and retains two lone pairs. This gives five regions of electron density (3 bonding pairs + 2 lone pairs) around iodine. According to VSEPR (Valence Shell Electron Pair Repulsion) theory, five regions of electron density adopt a trigonal bipyramidal electron geometry.
However, because two of those regions are lone pairs, the actual molecular geometry is T-shaped, with the lone pairs occupying equatorial positions to minimize electron pair repulsion. The three bonded atoms (chlorines) form a T-shaped molecule, not a trigonal planar or tetrahedral one. The presence of lone pairs causes distortion in bond angles, making the actual angles slightly less than 90°.
Both molecules demonstrate how VSEPR theory and electron distribution determine molecular shape. Iodine’s ability to expand its octet (as a third-period element) allows ICl₃ to exist with more than eight electrons around the central atom, illustrating a key exception to the octet rule.
