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LESSON-4.3_VSEPR-Model (1).pptx
- 1. Valence Shell ElectronPair Repulsion through Theory JOVELYN B. DAHANG Pre-Service Teacher
- 3. LEARNING OBJECTIVES At theend of the lesson, you will be able to 1. identify the different geometric shapes of molecules using diagrams ; and 2. Predict the structures and shapes of molecules using the VSEPR model.
- 4. REVIEW: Which isthe correct Lewis dot structure of the following atoms/molecules?
- 5. REVIEW: Which isthe correct Lewis dot structure of the following atoms/molecules?
- 6. REVIEW: Which isthe correct Lewis dot structure of the following atoms/molecules? H2O A
- 7. Valence-Shell Electron PairRepulsion (VSEPR) model • Used to predict the three-dimensional shape of the molecules from the electron pairs that surround the central atoms of the molecule. • Also referred to as electron domain model. • Two primary founders of this model are Ronald Nyholm and Ronald Gillespie.
- 8. The electron pairsin the valence shell of a central atom repel each other. Valence-Shell Electron Pair Repulsion (VSEPR) model BASIC ASSUMPTIONS
- 9. Three main typesof bond repulsion Lone pair – lone pair repulsion Lone pair – bonded pair repulsion Bonded pair – bonded pair repulsion Valence-Shell Electron Pair Repulsion (VSEPR) model BASIC ASSUMPTIONS
- 10. Lone pairs ornon- bonding pairs exerts greater repulsion than bonded pairs. Lone pair – lone pair repulsion > Lone pair – bonded pair repulsion > Bonded pair – bonded pair repulsion Valence-Shell Electron Pair Repulsion (VSEPR) model BASIC ASSUMPTIONS
- 11. 3 A multiple bondis treated as if it is a single electron pair and the two or three electron pairs of a multiple bond are treated as a single super pair. Valence-Shell Electron Pair Repulsion (VSEPR) model BASIC ASSUMPTIONS
- 12. The ED modelassumes that the shape of a molecule can be predicted by arranging the electrons in a geometry that keeps them separated as far as possible.
- 13. How to determinethe actual geometry of a molecule? STEP 1. Draw the Lewis Structure. C O O C STEP 2. Count the total number of electron domains of the central atom 2
- 14. How to determinethe actual geometry of a molecule? STEP 3. Identify the electron domain geometry of the molecule. STEP 4. Identify the molecular group geometry and the bond angles between atoms in the molecule. Linear Linear
- 15. How to determinethe actual geometry of a molecule? STEP 1. Draw the Lewis Structure. STEP 2. Count the total number of electron domains of the central atom 3 B F F F
- 16. How to determinethe actual geometry of a molecule? STEP 3. Identify the electron domain geometry of the molecule. STEP 4. Identify the molecular group geometry and the bond angles between atoms in the molecule. Trigonal Planar Trigonal Planar
- 17. How to determinethe actual geometry of a molecule? STEP 1. Draw the Lewis Structure. STEP 2. Count the total number of electron domains of the central atom 3 N O O NOTE: Nonbonding electrons are classified as electron domains
- 18. How to determinethe actual geometry of a molecule? STEP 3. Identify the electron domain geometry of the molecule. STEP 4. Identify the molecular group geometry and the bond angles between atoms in the molecule. Bent N O O
- 19. How to determinethe actual geometry of a molecule? STEP 1. Draw the Lewis Structure. STEP 2. Count the total number of electron domains of the central atom 4 C H H H H
- 20. How to determinethe actual geometry of a molecule? STEP 3. Identify the electron domain geometry of the molecule. STEP 4. Identify the molecular group geometry and the bond angles between atoms in the molecule. Tetrahedral Tetrahedral
- 21. How to determinethe actual geometry of a molecule? STEP 1. Draw the Lewis Structure. STEP 2. Count the total number of electron domains of the central atom 4 N H H H
- 22. How to determinethe actual geometry of a molecule? STEP 3. Identify the electron domain geometry of the molecule. STEP 4. Identify the molecular group geometry and the bond angles between atoms in the molecule. Trigonal Pyramidal
- 23. How to determinethe actual geometry of a molecule? STEP 1. Draw the Lewis Structure. STEP 2. Count the total number of electron domains of the central atom 4 O H H
- 24. How to determinethe actual geometry of a molecule? STEP 3. Identify the electron domain geometry of the molecule. STEP 4. Identify the molecular group geometry and the bond angles between atoms in the molecule. Bent
- 25. How to determinethe actual geometry of a molecule? STEP 1. Draw the Lewis Structure. STEP 2. Count the total number of electron domains of the central atom 5
- 26. How to determinethe actual geometry of a molecule? STEP 3. Identify the electron domain geometry of the molecule. STEP 4. Identify the molecular group geometry and the bond angles between atoms in the molecule. Trigonal bipyramidal
- 27. How to determinethe actual geometry of a molecule? STEP 1. Draw the Lewis Structure. STEP 2. Count the total number of electron domains of the central atom 6
- 28. How to determinethe actual geometry of a molecule? STEP 3. Identify the electron domain geometry of the molecule. STEP 4. Identify the molecular group geometry and the bond angles between atoms in the molecule. Octahedral