Question 3.15: Predicting Bond Angles In Covalent Compounds Predict all bon...
Predicting Bond Angles In Covalent Compounds
Predict all bond angles and the shape of each molecule:
(a) \text{CH}_{3}\text{Cl} (b) \text{CH}_{2}=\text{CHCl}
Strategy
To predict bond angles, first draw a correct Lewis structure for the compound. Be certain to show all unpaired electrons. Then determine the number of regions of electron density (either 2, 3, or 4) around each atom and use that number to predict bond angles (either 109.5°, 120°, or 180°).
(a) The Lewis structure for \text{CH}_{3}\text{Cl} shows that four regions of electron density surround carbon. Therefore, we predict that the distribution of electron pairs about carbon is tetrahedral, all bond angles are 109.5°, and the shape of \text{CH}_{3}\text{Cl} is tetrahedral.
(b) In the Lewis structure for \text{CH}_{2}=\text{CHCl}, three regions of electron density surround each carbon. Therefore, we predict that all bond angles are 120° and that the molecule is planar. The bonding about each carbon is trigonal planar.
■ Quick Check 3.15
Predict all bond angles for these molecules:
(a) \text{CH}_{3}\text{OH} (b) \text{CH}_{2}\text{Cl}_{2} (c) \text{H}_{2}\text{CO}_{3} (carbonic acid)