📚 Topic Summary
Valence Shell Electron Pair Repulsion (VSEPR) theory is used to predict the shapes of molecules based on the idea that electron pairs, whether bonding or non-bonding (lone pairs), repel each other and arrange themselves to maximize the distance between them. This arrangement minimizes repulsion and determines the molecule's geometry. The number of bonding pairs and lone pairs around the central atom dictates the electron-pair geometry, which then influences the molecular geometry. Remember that lone pairs exert a slightly greater repulsive force than bonding pairs, affecting bond angles.
🧪 Part A: Vocabulary
Match the following terms with their definitions:
| Term |
Definition |
| 1. Electron-Pair Geometry |
a. The shape of a molecule considering only the positions of the atoms. |
| 2. Molecular Geometry |
b. An atom or group of atoms attached to a central atom. |
| 3. Ligand |
c. The arrangement of electron pairs (bonding and non-bonding) around the central atom. |
| 4. Lone Pair |
d. A pair of electrons that is not involved in bonding. |
| 5. Bond Angle |
e. The angle formed between two bonds originating from the same central atom. |
(Answers: 1-c, 2-a, 3-b, 4-d, 5-e)
🧩 Part B: Fill in the Blanks
Complete the following paragraph using the words provided (words may be used more than once or not at all): repulsion, VSEPR, bonding, lone pairs, geometry, electron pairs, central atom, molecular.
The _______ theory helps predict the _______ of molecules. It is based on the principle that _______ around the _______ repel each other. Both _______ pairs and _______ contribute to this _______, and the molecule adopts a shape that minimizes this. The arrangement of atoms gives rise to _______ geometry.
(Answers: VSEPR, geometry, electron pairs, central atom, bonding, lone pairs, repulsion, molecular)
🤔 Part C: Critical Thinking
Explain how the presence of lone pairs on the central atom affects the bond angles in a molecule, and provide an example to illustrate your explanation.