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Ch.11 - Chemical Bonding II: Molecular Shapes, VSEPR & MO Theory
Chapter 11, Problem 34c

For each molecular geometry, list the number of total electron groups, the number of bonding groups, and the number of lone pairs on the central atom. (c)
3D representation of molecular geometry showing electron groups and bonding in a cubic structure.

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Identify the central atom in the molecular geometry. In this case, it is the atom at the center of the structure.
Count the total number of electron groups around the central atom. Electron groups include bonding pairs (single, double, or triple bonds) and lone pairs of electrons.
Determine the number of bonding groups around the central atom. Bonding groups are the number of atoms directly bonded to the central atom.
Determine the number of lone pairs on the central atom. Lone pairs are pairs of valence electrons that are not involved in bonding.
Summarize the findings: list the total number of electron groups, the number of bonding groups, and the number of lone pairs on the central atom.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Molecular Geometry

Molecular geometry refers to the three-dimensional arrangement of atoms within a molecule. It is determined by the number of electron groups around the central atom, which includes both bonding pairs and lone pairs. Understanding molecular geometry is crucial for predicting the shape and reactivity of molecules, as it influences properties such as polarity and intermolecular interactions.
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Electron Groups

Electron groups are regions of electron density around a central atom, which can be bonding pairs (shared between atoms) or lone pairs (non-bonding electrons). The total number of electron groups determines the molecular geometry according to the VSEPR (Valence Shell Electron Pair Repulsion) theory, which states that electron groups will arrange themselves to minimize repulsion between them.
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VSEPR Theory

VSEPR (Valence Shell Electron Pair Repulsion) theory is a model used to predict the geometry of individual molecules based on the repulsion between electron pairs in the valence shell of the central atom. By considering the number of bonding and lone pairs, VSEPR theory helps to determine the molecular shape, which is essential for understanding chemical behavior and interactions.
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