VSEPR Theory Part 2: Trigonal Bipyramidal Family

TL;DR

This video explains the three-dimensional shapes of molecules with five things around the central atom, including examples and bond angles.

Transcript

in this video we're going to look at the three-dimensional Vesper shape for molecules with five things around the central atom examples of some of these molecules are right here so what do I mean when I'm talking about five things around the central atom well here is the central atom in these guys okay and these five things can either be five bonds... Read More

Key Insights

• 🫀 Molecules with five things around the central atom can have various combinations of bonds and lone electron pairs.
• 😃 The trigonal bi-pyramidal shape is a common structure for these molecules.
• 💠 The seesaw, T-shaped, and linear shapes are variations of the trigonal bi-pyramidal shape.
• 🔺 Bond angles vary depending on the presence of lone electron pairs, with smaller angles observed when repulsion occurs.

Questions & Answers

Q: What are the different possibilities for the number of bonds and lone electron pairs around a central atom in these molecules?

The central atom can have five bonds, four bonds and one lone electron pair, three bonds and two lone electron pairs, or two bonds and three lone electron pairs.

Q: How does the trigonal bi-pyramidal shape differ from the other shapes?

The trigonal bi-pyramidal shape consists of a central atom surrounded by three axial atoms in a straight line and two equatorial atoms in a triangle shape. The other shapes are variations of this structure.

Q: How do the bond angles differ in these shapes?

In the trigonal bi-pyramidal shape, the axial and equatorial bond angles are 90 degrees, and the angle between axial bonds is 180 degrees. In the seesaw shape, these angles are slightly smaller due to repulsion from lone electron pairs. The T-shaped shape also has smaller angles, and the linear shape has an angle of 180 degrees.

Q: How can the three-dimensional shape of a molecule be determined from its Lewis structure?

By identifying the number of bonds and lone electron pairs in the Lewis structure, one can determine the shape of the molecule by considering which atoms are absent based on the desired structure.

Summary & Key Takeaways

• Molecules with five things around the central atom can consist of five bonds, four bonds and one lone electron pair, three bonds and two lone electron pairs, or two bonds and three lone electron pairs.

• The shapes of these molecules include trigonal bi-pyramidal, seesaw, T-shaped, and linear.

• The bond angles in these shapes vary, with 90 degrees, 180 degrees, and 120 degrees being important angles to keep in mind.