Textbook Question
Compare the Lewis structures of CH4 and H2O Why do these molecules have similar bond angles but different molecular shapes?
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Ch.6 Ionic and Molecular Compounds
Timberlake13th EditionChemistry: An Introduction to General, Organic, and Biological ChemistryISBN: 9780134421353
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Table of contents
- Ch.1 Chemistry in Our Lives11
- Ch.2 Chemistry and Measurements80
- Ch.3 Matter and Energy54
- Ch.4 Atoms and Elements51
- Ch.5 Nuclear Chemistry42
- Ch.6 Ionic and Molecular Compounds57
- Ch.7 Chemical Quantities and Reactions41
- Ch.8 Gases29
- Ch.9 Solutions51
- Ch.10 Acids and Bases and Equilibrium65
- Ch.11 Introduction to Organic Chemistry: Hydrocarbons78
- Ch.12 Alcohols, Thiols, Ethers, Aldehydes, and Ketones83
- Ch.13 Carbohydrates54
- Ch.14 Carboxylic Acids, Esters, Amines, and Amides90
- Ch.15 Lipids61
- Ch.16 Amino Acids, Proteins, and Enzymes84
- Ch.17 Nucleic Acids and Protein Synthesis83
- Ch.18 Metabolic Pathways and ATP Production67
Timberlake13th EditionChemistry: An Introduction to General, Organic, and Biological ChemistryISBN: 9780134421353Not the one you use?Change textbook
Chapter 6, Problem 71b
Choose the shape (1 to 6) that matches each of the following descriptions (a to c):
1. linear
2. bent (109°)
3. trigonal planar
4. bent (120°)
5. trigonal pyramidal
6. tetrahedral
b. a molecule with a central atom that has four electron groups and three bonded atoms
Verified step by step guidance1
Step 1: Understand the concept of electron groups. Electron groups include bonded atoms (single, double, or triple bonds count as one group) and lone pairs of electrons around the central atom.
Step 2: Recognize that the problem specifies four electron groups around the central atom. This indicates the molecule is based on a tetrahedral electron geometry.
Step 3: Note that the central atom has three bonded atoms and one lone pair. The presence of a lone pair modifies the molecular shape from the ideal tetrahedral geometry.
Step 4: Recall that when there are three bonded atoms and one lone pair, the molecular shape is described as 'trigonal pyramidal.' This is because the lone pair repels the bonded atoms, creating a three-sided pyramid-like structure.
Step 5: Match the description to the provided options. The correct shape for a molecule with four electron groups, three bonded atoms, and one lone pair is 'trigonal pyramidal,' which corresponds to option 5.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Electron Groups
Electron groups refer to regions of electron density around a central atom in a molecule. These can include lone pairs, single bonds, double bonds, or triple bonds. The number of electron groups determines the molecular geometry, as they repel each other and arrange themselves to minimize repulsion.
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Molecular Geometry
Molecular geometry describes the three-dimensional arrangement of atoms in a molecule. It is influenced by the number of electron groups around the central atom and their spatial orientation. Understanding molecular geometry is crucial for predicting the shape and reactivity of molecules.
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Trigonal Pyramidal Shape
A trigonal pyramidal shape occurs when a central atom is bonded to three other atoms and has one lone pair of electrons. This arrangement results in a pyramid-like structure with the bonded atoms at the base and the lone pair at the apex, leading to bond angles that are typically less than 109.5°.
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Related Practice
Textbook Question
Complete each of the following statements for a molecule of H2S:
c. The number of atoms attached to the central S atom is _______.
Textbook Question
Compare the Lewis structures of CF4 and NF3 Why do these molecules have different shapes?
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Textbook Question
Which electronegativity difference (a, b, or c) would you expect for a nonpolar covalent bond?
a. from 0.0 to 0.4
b. from 0.5 to 1.8
c. from 1.9 to 3.3
Textbook Question
Draw the Lewis structure for each of the following molecules:
d. ClNO2 (N is the central atom)
Textbook Question
For each of the following bonds, indicate the positive end with 𝛿⁺ and the negative end with 𝛿⁻ . Draw an arrow to show the dipole for each.
a. N and F