AXN Notation and Molecular Geometry

The video tutorial explores the molecular geometry of PBr3, starting with its Lewis structure and moving to a 3D perspective using valence shell electron pair repulsion theory. The AXN notation is introduced to predict the shape and bond angles of PBr3, identifying it as trigonal pyramidal with bond angles around 101 degrees. The tutorial concludes with a visualization of the 3D structure and a discussion on the experimental bond angles.

What is the main limitation of the Lewis structure when representing molecules like PBr3?

• It does not indicate the number of valence electrons.

• It does not show the types of atoms involved.

• It only provides a 2D representation, not the 3D shape.

• It cannot represent ionic bonds.

According to the valence shell electron pair repulsion theory, how do electron pairs arrange themselves?

• They cluster together as closely as possible.

• They align in a straight line.

• They spread out as far apart as possible.

• They form a circular pattern around the nucleus.

What does the 'A' represent in AXN notation?

• The type of bonds present.

• The number of atoms bonded to the central atom.

• The central atom.

• The number of lone pairs.

In AXN notation, what does the 'X' stand for?

• The number of lone pairs.

• The number of atoms bonded to the central atom.

• The type of bonds present.

• The central atom.

How many lone pairs are present on the phosphorus atom in PBr3?

• None

• One

• Two

• Three

What is the molecular geometry of PBr3 according to AXN notation?

• Tetrahedral

• Trigonal pyramidal

• Trigonal planar

• Linear

What is the expected bond angle for a trigonal pyramidal molecule like PBr3?

• 180 degrees

• 109.5 degrees

• 120 degrees

• 90 degrees

What is the experimentally determined bond angle for PBr3?

• 90 degrees

• 101 degrees

• 120 degrees

• 109.5 degrees

Which color is used to represent phosphorus in the 3D molecular model of PBr3?

• Blue

• Red

• Green

• Orange

What is the significance of the lone pair in determining the shape of PBr3?

• It makes the molecule planar.

• It contributes to the trigonal pyramidal shape.

• It causes the molecule to be linear.

• It has no effect on the shape.