Draw the Lewis structure of iodine trifluoride (IF
) that has the least amount of formal charge on the atoms. Marvin JS What is the electron-domain geometry of iodine trifluoride? What is the shape (molecular geometry) of iodine trifluoride? Does the molecule exhibit resonance?
Draw the Lewis structure of iodine trifluoride (IF
) that has the least amount of formal charge on the atoms. Marvin JS What is the electron-domain geometry of iodine trifluoride? What is the shape (molecular geometry) of iodine trifluoride? Does the molecule exhibit resonance
The Correct Answer and Explanation is:
Lewis Structure of Iodine Trifluoride (IF₃)
To draw the Lewis structure of iodine trifluoride (IF₃):
- Count valence electrons:
- Iodine (I): 7 valence electrons
- Fluorine (F): 7 × 3 = 21 valence electrons
- Total = 28 valence electrons
- Determine central atom:
Iodine is less electronegative than fluorine, so it will be the central atom. - Connect atoms with single bonds:
Connect I to each of the three F atoms with single bonds. This uses 3 × 2 = 6 electrons. - Distribute remaining electrons:
- 28 – 6 = 22 electrons left
- Place 6 electrons (3 lone pairs) on each F to complete their octets (18 electrons used).
- 4 electrons remain, placed as 2 lone pairs on iodine.
- Check for formal charge and stability:
- Iodine has 3 bonding pairs and 2 lone pairs = 10 electrons (expanded octet is allowed for iodine).
- Each F has 6 non-bonding + 1 bonding pair = 7 electrons (satisfied octet).
- Formal charges are minimized and zero for all atoms.
Lewis Structure:
..
:F:
|
.. :F—I—F: ..
..
(Iodine has two lone pairs; each fluorine has three.)
Electron-Domain Geometry
The electron-domain geometry of IF₃ is trigonal bipyramidal. This is because there are 5 regions of electron density (3 bonding pairs + 2 lone pairs) around iodine.
Molecular Geometry (Shape)
The molecular geometry (actual shape) of IF₃ is T-shaped. The two lone pairs occupy equatorial positions to minimize electron repulsion, and the three fluorine atoms occupy the remaining positions — two axial and one equatorial.
Resonance
IF₃ does not exhibit resonance.
There are no delocalized electrons or multiple possible locations for double bonds. Each F is singly bonded to I, and the lone pairs are localized. Resonance structures occur only when multiple equivalent bonding patterns exist, which is not the case here.
Summary
- Lewis Structure: I at center, 3 F atoms with single bonds, 2 lone pairs on I
- Electron-Domain Geometry: Trigonal bipyramidal
- Molecular Geometry: T-shaped
- Resonance: No resonance structures possible
