Ch.9 - Molecular Geometry and Bonding Theories

Brown - Chemistry: The Central Science 15th Edition

Brown15th EditionChemistry: The Central ScienceISBN: 9780137542970Not the one you use?Change textbook

Brown 15th Edition

Ch.9 - Molecular Geometry and Bonding Theories

Problem 11a1

Chapter 9, Problem 11a1

For each of these contour representations of molecular orbitals, identify (a) the atomic orbitals (s or p) used to construct the MO (i)

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Observe the contour representation of the molecular orbital in the image. Note the positive and negative regions indicated by the '+' and '-' signs.

Identify the shape of the orbitals. The lobes with a '+' and '-' sign suggest that these are p orbitals, as s orbitals are spherical and do not have such lobes.

Determine the type of interaction between the atomic orbitals. The presence of both positive and negative regions indicates that this is a bonding molecular orbital formed by the constructive interference of p orbitals.

Note the symmetry of the molecular orbital. The image shows a sigma (σ) bond, as the electron density is concentrated along the internuclear axis.

Conclude that the molecular orbital is constructed from the overlap of two p atomic orbitals, forming a sigma (σ) bonding molecular orbital.

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Key Concepts

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

Molecular Orbitals (MOs)

Molecular orbitals are formed by the linear combination of atomic orbitals (LCAO) when atoms bond together. They can be classified as bonding, antibonding, or non-bonding, depending on the phase relationship of the combining atomic orbitals. The shape and energy of these orbitals determine the stability and reactivity of the molecule.

Atomic Orbitals

Atomic orbitals are regions in an atom where there is a high probability of finding electrons. They are categorized into different types, such as s (spherical) and p (dumbbell-shaped), each with distinct shapes and orientations. The combination of these orbitals during molecular formation leads to the creation of molecular orbitals.

Contour Representation

Contour representation visually depicts the regions of positive and negative phase in molecular orbitals. The positive regions indicate where the probability of finding electrons is high, while the negative regions show areas of destructive interference. This representation helps in understanding the bonding characteristics and electron distribution within the molecule.

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Related Practice

Textbook Question

The molecule shown here is called furan. It is represented in the typical shorthand way for organic molecules, with hydrogen atoms not shown, and each of the four vertices representing a carbon atom. e. The bond angles in furan are much smaller than those in benzene. The likely reason is which of the following? i. The hybridization of the carbon atoms in furan is different from that in benzene. ii. Furan does not have another resonance structure equivalent to the one shown here. iii. The atoms are forced to adopt smaller angles in a five-membered ring than in a six-membered ring. [Section 9.5]

Textbook Question

The following is part of a molecular orbital energy-level diagram for MOs constructed from 1s atomic orbitals.

(a) What labels do we use for the two MOs shown?

Textbook Question

For each of these contour representations of molecular orbitals, identify (a) the atomic orbitals (s or p) used to construct the MO (iii)

Textbook Question

For each of these contour representations of molecular orbitals, identify (b) the type of MO (s or p) (iii)

Textbook Question

For each of these contour representations of molecular orbitals, identify (b) the type of MO (s or p) (i)

Textbook Question

For each of these contour representations of molecular orbitals, identify (c) whether the MO is bonding or antibonding (i)