Each ball-and-stick model shows the electron and molecular geometry of a generic molecule. Explain what is wrong with each molecular geometry and provide the correct molecular geometry, given the number of lone pairs and bonding groups on the central atom. (c)

Verified step by step guidance

1. Identify the central atom and count the number of bonding groups and lone pairs around it. In this case, sulfur (S) is the central atom with 3 bonding groups (F atoms) and 1 lone pair.
2. Determine the electron geometry based on the total number of electron groups (bonding groups + lone pairs). For 4 electron groups, the electron geometry is tetrahedral.
3. Determine the molecular geometry by considering only the bonding groups. With 3 bonding groups and 1 lone pair, the molecular geometry is trigonal pyramidal.
4. Compare the given molecular geometry in the image with the correct molecular geometry. The image shows a trigonal planar geometry, which is incorrect.
5. Correct the molecular geometry to trigonal pyramidal, considering the lone pair on the sulfur atom which affects the shape.

Key Concepts

VSEPR Theory

Valence Shell Electron Pair Repulsion (VSEPR) Theory is a model used to predict the geometry of individual molecules based on the repulsion between electron pairs around a central atom. According to this theory, electron pairs, whether bonding or lone pairs, will arrange themselves to minimize repulsion, leading to specific molecular shapes.

Lone Pairs vs. Bonding Pairs

In molecular geometry, lone pairs are non-bonding pairs of electrons that occupy space around the central atom, influencing its shape. Bonding pairs, on the other hand, are shared between atoms to form bonds. The presence of lone pairs can distort the ideal bond angles and alter the expected geometry of the molecule.

Molecular Geometry vs. Electron Geometry

Molecular geometry refers to the three-dimensional arrangement of atoms in a molecule, while electron geometry considers the spatial arrangement of all electron pairs, including lone pairs. Understanding the distinction is crucial, as the presence of lone pairs can lead to different molecular geometries than what would be predicted based solely on bonding pairs.