Draw the Lewis structure for carbonyl fluoride, COF2. What are teh electron-pair geometry and molecular geometry around the central atom? What is the hybridization of the carbon atom? What orbitals overlap to form the σ and π bonds between carbon and oxygen’s?
Draw the Lewis structure for carbonyl fluoride, COF2. What are teh electron-pair geometry and molecular geometry around the central atom? What is the hybridization of the carbon atom? What orbitals overlap to form the σ and π bonds between carbon and oxygen’s?
The Correct Answer and Explanation is:
Lewis Structure for COF₂ (Carbonyl Fluoride):
- Count valence electrons:
- Carbon (C): 4 valence electrons
- Oxygen (O): 6 valence electrons
- Fluorine (F): 7 valence electrons × 2 = 14
Total = 4 + 6 + 14 = 24 valence electrons
- Connect atoms:
- Carbon is the central atom.
- Attach oxygen and two fluorines to carbon with single bonds.
- Distribute remaining electrons:
- Place lone pairs on oxygen and fluorine atoms to complete octets.
- You will notice that oxygen has only 6 electrons — form a double bond between carbon and oxygen.
Final Lewis Structure:
F
|
O=C—F
- Carbon forms 2 single bonds with fluorines and 1 double bond with oxygen.
- Fluorines and oxygen each have 3 lone pairs.
Electron-Pair Geometry:
- Carbon has three electron domains (2 single bonds to F, 1 double bond to O).
- This corresponds to trigonal planar electron-pair geometry.
Molecular Geometry:
- Since all domains are bonding (no lone pairs on C), the molecular geometry is also trigonal planar.
Hybridization of Carbon:
- Carbon has 3 regions of electron density → sp² hybridization
Bonding Orbitals:
- The σ (sigma) bond between carbon and oxygen is formed by overlap of an sp² orbital from carbon and an sp² orbital from oxygen.
- The π (pi) bond in the C=O bond is formed by side-to-side overlap of unhybridized p orbitals on carbon and oxygen.
- The C–F σ bonds are formed by overlap of carbon’s sp² orbitals with fluorine’s p orbitals.
Explanation
Carbonyl fluoride (COF₂) is a molecule composed of one carbon atom bonded to one oxygen atom and two fluorine atoms. To draw its Lewis structure, we begin by counting valence electrons: carbon contributes 4, oxygen contributes 6, and each fluorine contributes 7, giving a total of 24 valence electrons. Carbon, being the least electronegative, is placed in the center. Single bonds are formed between carbon and each of the other atoms, and lone pairs are assigned to satisfy octets. To satisfy the octet rule for oxygen, a double bond is formed between carbon and oxygen, using a lone pair from oxygen to create the second bonding pair.
This results in carbon forming three bonds (one double and two single), giving it three regions of electron density. The ideal geometry for three regions of electron density is trigonal planar, which applies both to the electron-pair and molecular geometries of COF₂. All bond angles are approximately 120°.
To accommodate this geometry, the carbon atom undergoes sp² hybridization, meaning one s orbital and two p orbitals mix to form three equivalent sp² orbitals, which lie in a plane 120° apart. Two of these sp² orbitals form σ bonds with the fluorine atoms, and the third forms a σ bond with oxygen. The remaining unhybridized p orbital on carbon overlaps sideways with a p orbital on oxygen to form the π bond in the C=O double bond.
This orbital overlap explains the double bond character and planarity of the molecule. Fluorine atoms, being highly electronegative, stabilize the structure with strong C–F σ bonds. The Lewis structure and bonding analysis confirm that COF₂ has a planar geometry with sp² hybridized carbon and a polar character due to the electronegativity differences.
