📚 Topic Summary
London Dispersion Forces (LDF), also known as Van der Waals forces, are the weakest type of intermolecular force. They arise from temporary fluctuations in electron distribution within molecules. Even nonpolar molecules experience these forces because, at any given moment, electrons can be unevenly distributed, creating a temporary dipole. The larger the molecule and the more electrons it has, the stronger the LDFs become because there's a greater chance of these temporary dipoles forming. These forces are crucial for understanding the physical properties of many substances, especially those made of nonpolar molecules.
These temporary dipoles induce dipoles in neighboring molecules, leading to an attraction. Imagine it like this: one molecule gets a little lopsided with its electrons, and that makes its neighbor get a little lopsided too, and they stick together! The strength of LDFs increases with molecular size and the number of electrons.
🧪 Part A: Vocabulary
Match each term with its correct definition:
| Term |
Definition |
| 1. London Dispersion Forces |
A. A temporary uneven distribution of electrons in a molecule. |
| 2. Intermolecular Forces |
B. The forces of attraction between molecules. |
| 3. Temporary Dipole |
C. The weakest intermolecular force, resulting from temporary fluctuations in electron distribution. |
| 4. Polarizability |
D. The ease with which the electron cloud of an atom or molecule can be distorted. |
| 5. Nonpolar molecule |
E. A molecule with an equal distribution of electrons. |
Match the terms with the correct definition. (Answers: 1-C, 2-B, 3-A, 4-D, 5-E)
🔬 Part B: Fill in the Blanks
Fill in the missing words in the paragraph below:
London Dispersion Forces are a type of __________ force that occurs between all molecules, including __________ molecules. These forces arise from temporary __________ in electron distribution, creating temporary __________. The strength of LDFs increases with __________ size and the number of __________.
(Answers: intermolecular, nonpolar, fluctuations, dipoles, molecular, electrons)
🤔 Part C: Critical Thinking
Explain why larger molecules tend to have stronger London Dispersion Forces compared to smaller molecules.
(Answer: Larger molecules have more electrons and a larger surface area. This means there's a greater chance of temporary dipoles forming and a larger area for interaction with neighboring molecules, resulting in stronger London Dispersion Forces.)