Compound Total Valence Lewis Structure Electron Pair Molecular Approximate Polar? Electrons Geometry Geometry Bond Angles SO3 24 trigonal trigonal planar planar HCN H-C?N SO2 18 CS2 CH4 8 H H-C-H tetrahedral tetrahedral H
The Correct Answer and Explanation is:
Let’s break down the molecular structures and their key features for each compound:
1. SO3 (Sulfur Trioxide)
- Total Valence Electrons: 24
- Electron Pair Geometry: Trigonal
- Molecular Geometry: Trigonal Planar
- Bond Angles: 120°
- Polarity: Nonpolar
SO3 has 24 valence electrons, and in its structure, the central sulfur atom is bonded to three oxygen atoms through double bonds. This leads to a trigonal planar geometry with 120° bond angles. Because the molecule has symmetry and no lone pairs on the central sulfur, it is nonpolar.
2. HCN (Hydrogen Cyanide)
- Total Valence Electrons: 10
- Electron Pair Geometry: Linear
- Molecular Geometry: Linear
- Bond Angles: 180°
- Polarity: Polar
HCN has 10 valence electrons, with a linear structure. The molecule consists of a hydrogen atom bonded to a carbon atom, which is triple-bonded to a nitrogen atom. This molecule is linear with a bond angle of 180°. Since the electronegativities of carbon and nitrogen differ, HCN is polar.
3. SO2 (Sulfur Dioxide)
- Total Valence Electrons: 18
- Electron Pair Geometry: Trigonal
- Molecular Geometry: Bent
- Bond Angles: 120°
- Polarity: Polar
SO2 has 18 valence electrons and adopts a trigonal electron pair geometry, with a bent molecular geometry due to the lone pair on sulfur. This results in a bond angle of approximately 120°. SO2 is polar because of its asymmetric structure.
4. CS2 (Carbon Disulfide)
- Total Valence Electrons: 16
- Electron Pair Geometry: Linear
- Molecular Geometry: Linear
- Bond Angles: 180°
- Polarity: Nonpolar
CS2 has 16 valence electrons, and its structure is linear, with a carbon atom bonded to two sulfur atoms by double bonds. The bond angle is 180°, and the molecule is nonpolar due to its symmetric linear shape.
5. CH4 (Methane)
- Total Valence Electrons: 8
- Electron Pair Geometry: Tetrahedral
- Molecular Geometry: Tetrahedral
- Bond Angles: 109.5°
- Polarity: Nonpolar
CH4 has 8 valence electrons and adopts a tetrahedral electron pair geometry, with four single bonds between carbon and hydrogen atoms. The bond angles are approximately 109.5°. Methane is nonpolar because of its symmetrical shape.
Summary:
- SO3: Nonpolar, trigonal planar (120°)
- HCN: Polar, linear (180°)
- SO2: Polar, bent (120°)
- CS2: Nonpolar, linear (180°)
- CH4: Nonpolar, tetrahedral (109.5°)
These molecules differ in polarity and geometry based on the distribution of electrons and bonding arrangements.
