What is the molecular geometry of NH3Cl+ and NH2-? Are they polar or non-polar? Briefly explain. After you examined the ball-and-stick model, what influenced the angle and shape of these molecules? Briefly explain using the VSEPR theory. What is the molecular geometry of the individual central atom of CH3COCH3 and CH3COOH? What is the overall polarity of each molecule? Briefly explain. After you examined the ball-and-stick model, what influenced the angle and shape of these molecules? Briefly explain using the VSEPR theory.
What is the molecular geometry of NH3Cl+ and NH2-? Are they polar or non-polar? Briefly explain. After you examined the ball-and-stick model, what influenced the angle and shape of these molecules? Briefly explain using the VSEPR theory. What is the molecular geometry of the individual central atom of CH3COCH3 and CH3COOH? What is the overall polarity of each molecule? Briefly explain. After you examined the ball-and-stick model, what influenced the angle and shape of these molecules? Briefly explain using the VSEPR theory.
The Correct Answer and Explanation is:
1. NH₃Cl⁺ (Ammonium chloride cation)
- Molecular Geometry: Tetrahedral
- Polarity: Polar
Explanation: NH₃Cl⁺ is derived from NH₄⁺ (ammonium ion) by replacing one hydrogen with a chlorine atom. The nitrogen atom has four regions of electron density (three N–H bonds and one N–Cl bond) and no lone pairs. According to VSEPR (Valence Shell Electron Pair Repulsion) theory, four bonding pairs around nitrogen form a tetrahedral geometry with bond angles close to 109.5°. However, the molecule is polar because Cl is significantly more electronegative than H, causing an uneven distribution of electron density.
2. NH₂⁻ (Amide anion)
- Molecular Geometry: Bent (Angular)
- Polarity: Polar
Explanation: The NH₂⁻ ion has two bonding pairs and two lone pairs on nitrogen, for a total of four electron domains. VSEPR predicts a bent geometry, similar to H₂O, with bond angles slightly less than 109.5°. The lone pairs repel more strongly than bonding pairs, reducing the H–N–H bond angle. The molecule is polar due to the lone pair and asymmetrical electron distribution.
3. CH₃COCH₃ (Acetone)
- Geometry around central atoms:
- C (in CH₃): Tetrahedral
- C=O (carbonyl carbon): Trigonal planar
- Overall Polarity: Polar
Explanation: The carbonyl carbon in acetone is sp² hybridized with trigonal planar geometry (120° bond angles). The methyl groups are sp³ hybridized with tetrahedral geometry. The polar C=O bond makes the whole molecule polar despite the symmetrical CH₃ groups.
4. CH₃COOH (Acetic acid)
- Geometry around central atoms:
- C (in CH₃): Tetrahedral
- C=O (carboxyl carbon): Trigonal planar
- Overall Polarity: Polar
Explanation: Similar to acetone, the carbonyl carbon is sp² hybridized (trigonal planar), and the methyl carbon is tetrahedral. The presence of both C=O and O–H bonds contributes to a strong dipole moment, making acetic acid highly polar.
VSEPR Theory Summary
VSEPR theory explains the shape and angles based on electron domain repulsion. Lone pairs exert greater repulsion than bonding pairs, influencing bond angles and molecular shape. Polar molecules arise from asymmetrical shapes or bonds with differing electronegativities.
