Question

Which of the following is NOT one of the main tenets of VSEPR theory?

Options:
(A) Since electrons repel one another, electron pairs attempt to move as far apart as possible.
(B) Lone pairs will repel slightly more than bonding pairs, decreasing the bond angles by about 2.5 degrees per lone pair.
(C) The electron and molecular geometries will always be the same, since they are both predicted by electron placement.
(D) For any central atom with a given number of lone pairs plus bonding pairs, the electron geometry will be identical.

Answer 1

The statement that is NOT a tenet of VSEPR theory is that electron and molecular geometries will always be the same. VSEPR predictions sometimes differ for molecular geometry due to the presence of lone pairs.

Step-by-step explanation:

The question asks which option is NOT one of the main tenets of VSEPR theory. The correct answer is (C) The electron and molecular geometries will always be the same since they are both predicted by electron placement. This statement is incorrect because while the VSEPR model predicts the electron geometry surrounding the central atom based on minimizing repulsions, the molecular geometry also takes into account the actual positions of the atoms, which can be different when there are lone pairs present. Lone pairs take up more space and can affect the molecular geometry, making it differ from the electron geometry. Options (A), (B), and (D) are consistent with VSEPR principles. Electron pairs, both bonding pairs and lone pairs, repel one another. Lone pairs repel more strongly than bonding pairs, which can lead to adjusting bond angles and consequently the geometric shapes.