QUESTION 12 What Is The Molecular Shape Of The Oxygen In Methanol, Shown Below? H-C-Q-H Р-Н O A. Linear O B. Bent O C. Trigonal Planar O D. Trigonal Pyramidal O E. Tetrahedral
The Correct Answer and Explanation is:
Correct Answer: B. Bent
Explanation:
In methanol (CH₃OH), the molecule consists of a central carbon atom bonded to three hydrogen atoms and one hydroxyl group (-OH). We are asked to determine the molecular shape around the oxygen atom specifically.
Step 1: Draw the Lewis Structure
Methanol’s Lewis structure shows:
- Carbon (C) forms four single bonds: three with hydrogen (H) atoms and one with the oxygen (O) atom.
- Oxygen (O) is bonded to one hydrogen and one carbon, and it has two lone pairs of electrons.
So, the oxygen atom in methanol has:
- 2 bonding pairs (O–H and O–C),
- 2 lone pairs.
Step 2: Apply VSEPR Theory
According to Valence Shell Electron Pair Repulsion (VSEPR) Theory, electron domains (bonding and lone pairs) arrange themselves to minimize repulsion.
The electron geometry for a central atom with four electron groups (2 bonds + 2 lone pairs) is tetrahedral. However, molecular shape is determined only by the positions of the atoms (not the lone pairs).
With two bonds and two lone pairs, the resulting molecular shape is bent (also known as “angular”).
This is similar to the shape of a water (H₂O) molecule, which also has two bonds and two lone pairs on the oxygen atom.
Step 3: Consider Bond Angles
Due to lone pair repulsion being stronger than bonding pair repulsion, the bond angle is slightly less than the tetrahedral angle of 109.5°, typically around 104.5° for a bent structure like in water and methanol.
Conclusion:
Thus, the molecular shape around the oxygen atom in methanol is bent, not linear, trigonal planar, trigonal pyramidal, or tetrahedral (the latter describes electron geometry, not molecular shape). The correct answer is B. Bent.
