For each of the following molecules, indicate the bond angle...

For each of the following molecules, indicate the bond angle expected between the central atom and any two adjacent chlorine atoms. $$ \begin{array}{ll}{\text { a. } C l_{2} O} & {\text { c. } \operatorname{BeCl}_{2}} \\ {\text { b. } C C l_{4}} & {\text { d. } B C l_{3}}\end{array} $$

For each of the following molecules, indicate the bond angle expected between the central atom and any two adjacent chlorine atoms.
$$
\begin{array}{ll}{\text { a. } C l_{2} O} & {\text { c. } \operatorname{BeCl}_{2}} \\ {\text { b. } C C l_{4}} & {\text { d. } B C l_{3}}\end{array}
$$

Key Concepts

Lone Pair Repulsion Effects

Lone pair repulsion effects are an important concept in determining molecular shapes. Lone pairs are more repulsive than bonding pairs because they are localized closer to the central atom, which can lead to a reduction in bond angles between the bonded atoms. This deviation from the ideal electron domain geometry explains why bond angles in molecules with lone pairs tend to be smaller than their ideal geometrical values.

Molecular Geometry

Molecular geometry describes the actual three-dimensional arrangement of atoms in a molecule, ignoring the lone pairs. This geometry is derived from the electron domain geometry but may present different observed bond angles if there are lone pairs present, as the lone pairs exert a stronger repulsive force compared to bonding pairs.

Electron Domain Geometry

Electron domain geometry refers to the spatial arrangement of all electron groups (both bonding pairs and lone pairs) around the central atom. By counting these electron domains, one can predict the basic geometric arrangement, such as linear, trigonal planar, tetrahedral, trigonal bipyramidal, or octahedral, each of which is associated with characteristic bond angles.

VSEPR Theory

Valence Shell Electron Pair Repulsion (VSEPR) theory is a model used to predict the geometry of molecules by considering the repulsions between electron pairs in the valence shell of the central atom. The idea is that electron pairs, whether bonded or lone pairs, will arrange themselves as far apart as possible to minimize repulsion, thereby determining the molecule’s shape and bond angles.

Transcript

00:01 In this question, we are using thesper to determine the bond angle in the following molecules.

00:08 So in part a, we are looking at cl2o.

00:12 We're going to determine how many electrons we are working with so we can draw our structure.

00:17 We have two chlorines, each with seven electrons, and we have an oxygen with six electrons.

00:22 That's 20 electrons to work with.

00:24 So we have chlorine, oxygen, and chlorine.

00:29 We have two bonds here, and each.

00:31 Each of our bonds contains two electrons.

00:35 So that means we have four electrons that have been accounted for and 16 remaining.

00:40 We distribute these on our chlorines first, so that's 6, 12.

00:46 We have four electrons remaining and those four will go on our central atom of oxygen.

00:54 So here we have four areas in which electrons exist, which means we are in the overall vespers arrangement of tetrahedral.

01:02 And these have bond angles of 109 .5 degrees.

01:07 Since we are dealing with two lone pairs, there will be some electron repulsion, making the bond angle slightly less than 109 .5 degrees.

01:16 In part b, we are looking at ccl4.

01:21 In this, we have a carbon with four valence electrons, and four chlorines, each with seven valence electrons.

01:26 That adds to 32.

01:28 Carbon is in the center with four chlorines surrounding, it.

01:34 We have four bonds each with two electrons, meaning eight electrons have been accounted for, and we have 24 remaining.

01:40 We fill our outer elements or outer atoms, so that's 6, 12, 18, and 24.

01:52 All our electrons have been accounted for.

01:55 We have four bonding domains, meaning we are in tetrahedral with 109 .5 degree bond angle...

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