VSEPR Theory and Molecular Shapes

The video tutorial explains the VSEPR theory for molecules with six surrounding atoms, focusing on three main shapes: octahedral, square pyramidal, and square planar. It describes the arrangement of atoms and electron pairs, the symmetry of these shapes, and the bond angles involved. The octahedral shape features six atoms symmetrically arranged around a central atom, with 90-degree bond angles. The square pyramidal shape has one atom replaced by a lone electron pair, causing bond angles to be slightly less than 90 degrees. The square planar shape has two atoms replaced by lone electron pairs, resulting in a flat, square arrangement with 90-degree bond angles.

What is the maximum number of lone pairs typically observed in molecules with six surrounding elements?

• One

• Three

• Two

• Four

Which molecule is used as an example to explain the octahedral shape?

• XeF4

• SF6

• NH3

• IF5

In an octahedral molecule, what is the bond angle between any two bonds?

• 60°

• 180°

• 90°

• 120°

What is the main difference between the octahedral and square pyramidal shapes?

• Number of atoms

• Presence of a lone pair

• Number of bonds

• Type of central atom

How does the lone pair in a square pyramidal shape affect the bond angles?

• Decreases them

• Increases them

• Keeps them the same

• Makes them 180°

What is the shape of a molecule with four atoms and two lone pairs around the central atom?

• Linear

• Trigonal bipyramidal

• Square planar

• Tetrahedral

In a square planar molecule, what is the bond angle between adjacent bonds?

• 120°

• 90°

• 60°

• 45°

Which VSEPR shape is described as having a flat structure with atoms in a single plane?

• Trigonal planar

• Square planar

• Square pyramidal

• Octahedral

What happens to the top and bottom atoms in an octahedral shape to form a square planar shape?

• They are removed

• They are replaced by bonds

• They are replaced by lone pairs

• They are doubled

Which of the following is NOT a characteristic of the square pyramidal shape?

• Five surrounding atoms

• Similar to octahedral

• All bond angles are 90°

• Presence of a lone pair