2015 AP Chemistry free response 2 d e | Summary and Q&A

TL;DR

This video explains how to draw the Lewis electron-dot diagram for ethanol and estimates the approximate bond angle in the ethanol molecule.

Key Insights

• 🫥 The Lewis electron-dot diagram can be used to represent the arrangement of valence electrons in a molecule.
• 🫀 In ethanol, hydrogen atoms contribute one electron each to each electron pair, carbon atoms contribute four valence electrons, and oxygen atoms have lone pairs.
• 🌀 The bond angle in ethanol is approximately between 104 and 110 degrees due to the repulsion between lone pairs of electrons.
• 🌀 The tetrahedral shape of the molecule and the presence of lone pairs influence the bond angle in ethanol.

Transcript

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Questions & Answers

Q: How do you complete the Lewis electron-dot diagram for ethanol?

To complete the Lewis electron-dot diagram for ethanol, you need to draw in all the electron pairs. Hydrogen atoms contribute one electron to each pair, while carbon atoms contribute four valence electrons. Oxygen atoms have lone pairs and contribute electrons to bonding pairs.

Q: What is the approximate bond angle in an ethanol molecule?

The bond angle in an ethanol molecule is approximately between 104 and 110 degrees. It is estimated based on the tetrahedral shape of the molecule, influenced by the repulsion between lone pairs of electrons.

Q: How many valence electrons does carbon have in ethanol?

Carbon in ethanol has four valence electrons. These four electrons are available for covalent bonding with other atoms present in the molecule.

Q: Why do lone pairs in oxygen affect the bond angle in ethanol?

Lone pairs in oxygen create a repulsion force that affects the bond angle in the ethanol molecule. The repulsion between lone pairs pushes the other atoms closer together, resulting in a smaller bond angle compared to a perfect tetrahedral shape.

Summary & Key Takeaways

• The video demonstrates how to complete the Lewis electron-dot diagram for ethanol by drawing in electron pairs from hydrogen, carbon, and oxygen atoms.

• It explains that each hydrogen contributes one electron to each pair, and each carbon contributes four valence electrons.

• The video also discusses the approximate bond angle in the ethanol molecule, which is estimated to be between 104 and 110 degrees.