Table of contents

1. Matter and Measurements4h 31m
2. Atoms and the Periodic Table5h 23m
3. Ionic Compounds2h 18m
4. Molecular Compounds2h 18m
5. Classification & Balancing of Chemical Reactions3h 17m
6. Chemical Reactions & Quantities2h 27m
7. Energy, Rate and Equilibrium3h 46m
8. Gases, Liquids and Solids3h 25m
9. Solutions4h 10m
10. Acids and Bases3h 29m
11. Nuclear Chemistry56m
BONUS: Lab Techniques and Procedures1h 38m
BONUS: Mathematical Operations and Functions47m
12. Introduction to Organic Chemistry1h 34m
13. Alkenes, Alkynes, and Aromatic Compounds2h 12m
14. Compounds with Oxygen or Sulfur1h 6m
15. Aldehydes and Ketones1h 1m
16. Carboxylic Acids and Their Derivatives1h 11m
17. Amines39m
18. Amino Acids and Proteins1h 51m
19. Enzymes1h 37m
20. Carbohydrates1h 41m
21. The Generation of Biochemical Energy2h 8m
22. Carbohydrate Metabolism2h 22m
23. Lipids2h 26m
24. Lipid Metabolism1h 45m
25. Protein and Amino Acid Metabolism1h 37m
26. Nucleic Acids and Protein Synthesis2h 54m

4. Molecular Compounds

Molecular Geometry (Simplified)

GOB Chemistry

4. Molecular Compounds

Molecular Geometry (Simplified)

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4:14 minutes

Problem 71b

Textbook Question

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 guidance

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.

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.

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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