Molecular Geometry and Bonding Concepts

The video tutorial explains the molecular geometry of phosphorus trihydride (PH3). It begins with the Lewis structure, showing three hydrogen atoms and a lone pair attached to phosphorus. The steric number is calculated as four, leading to a trigonal pyramidal geometry. The video demonstrates how the lone pair affects the bond angles, making them slightly less than 109.5 degrees. The tutorial concludes with a visual representation of the PH3 molecule and its geometry.

What is the steric number of PH3 based on its Lewis structure?

• 3

• 2

• 4

• 5

Which molecular geometry is associated with a steric number of 4 and one lone pair?

• Linear

• Trigonal pyramidal

• Tetrahedral

• Trigonal planar

How many hydrogen atoms are attached to the phosphorus atom in PH3?

• 2

• 4

• 1

• 3

What happens to the hydrogen atoms when the lone pair is added to the PH3 molecule?

• They form a linear arrangement

• They are pushed down

• They move closer together

• They spread out in a plane

What is the general bond angle in a trigonal pyramidal molecular geometry?

• 180 degrees

• 120 degrees

• 109.5 degrees

• 90 degrees

How does the lone pair affect the bond angle in PH3?

• It decreases the bond angle

• It increases the bond angle

• It makes the bond angle exactly 109.5 degrees

• It has no effect

What is the molecular geometry of PH3?

• Tetrahedral

• Trigonal planar

• Linear

• Trigonal pyramidal

Who is the narrator of the video?

• Dr. A

• Dr. B

• Dr. D

• Dr. C