Final answer:
Statement 5, which states that lone pairs of electrons on the central atom have no effect on the molecular geometry of a molecule or polyatomic ion, is false. Lone pairs significantly influence molecular geometry by altering the angles between bonding pairs.
Step-by-step explanation:
In addressing the question about which statement is false regarding the behavior and impact of lone pairs of electrons on molecular geometry, we must consider a few key concepts. First, lone pairs of electrons are indeed considered in the description of the electronic geometry, which identifies the spatial arrangement of all electron pairs (bonding and nonbonding) around a central atom. However, when determining molecular geometry, which is the arrangement of only the atoms in a molecule, lone pairs are not directly considered.
Lone pairs of electrons influence the shape of a molecule by exerting repulsive forces on bonding pairs, leading to distortions in molecular geometry. These lone pairs repel each other more strongly than they repel bonding pairs due to their closer proximity to the nucleus and lack of sharing with another atom, which gives them more localized electron density. Therefore, option 2, which states that lone pairs repel each other more strongly than bonding pairs, is true.
Similarly, option 3, which states that lone pairs repel each other more strongly than they repel bonding pairs, is also true. Option 4 aligns with our understanding and is true, reinforcing that lone pairs are not directly considered in the description of molecular geometry.
However, option 5 is false. It incorrectly asserts that lone pairs of electrons on the central atom have no effect on the molecular geometry of a molecule or polyatomic ion, when in fact, they have a significant effect because they alter the angles between the bonding pairs and thus the overall shape of the molecule.