Describe the bond angles to be found in each of the following molecular structures: (a) trigonal planar, (b) tetrahedral, (c) octahedral, (d) linear.

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Identify the molecular geometry for each structure: (a) trigonal planar, (b) tetrahedral, (c) octahedral, (d) linear.

Recall that the bond angles are determined by the electron pair geometry around the central atom.

For (a) trigonal planar, the bond angles are typically 120° due to the arrangement of three electron pairs around the central atom.

For (b) tetrahedral, the bond angles are typically 109.5° as four electron pairs are arranged in a three-dimensional space.

For (c) octahedral, the bond angles are typically 90° because six electron pairs are symmetrically arranged around the central atom, and for (d) linear, the bond angles are 180° as two electron pairs are directly opposite each other.

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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 bonding pairs and lone pairs of electrons around the central atom, which influences the shape and angles between bonds. Understanding molecular geometry is crucial for predicting bond angles and the overall structure of molecules.

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 in the valence shell of the central atom. According to VSEPR, electron pairs will arrange themselves to minimize repulsion, leading to specific bond angles characteristic of different molecular shapes, such as trigonal planar or tetrahedral.

Bond Angles

Bond angles are the angles formed between adjacent bonds in a molecule, which are influenced by the molecular geometry. For example, in a trigonal planar structure, bond angles are approximately 120 degrees, while in a tetrahedral structure, they are about 109.5 degrees. Understanding these angles is essential for predicting the behavior and reactivity of molecules.

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