Humber Admissions Practice Test

What does VSPER theory predict about molecular structures?

1. Pairs of valence electrons attract each other

2. Pairs of valence electrons repel each other

3. All molecular shapes are symmetrical

4. Molecules have fixed shapes regardless of conditions

The correct answer is: Pairs of valence electrons repel each other

VSEPR (Valence Shell Electron Pair Repulsion) theory posits that pairs of valence electrons surrounding an atom will arrange themselves as far apart as possible to minimize the repulsive forces between them. This is fundamental in determining the geometry of molecules. According to VSEPR theory, the repulsion between these electron pairs will dictate how atoms are arranged in three-dimensional space, leading to specific molecular shapes. This repulsion affects both bonding pairs (which form bonds between atoms) and lone pairs (which do not participate in bonding but still exert repulsive forces). As a result, VSEPR theory helps predict the molecular structure, which is crucial for understanding the behavior, reactivity, and properties of different substances. While the other options touch on aspects of molecular structure, they don't capture the essential principle emphasized by VSEPR theory regarding the electronic interactions and corresponding molecular geometries.