Final answer:
The molecule 3-chloro-3-methylpentane is not chiral because the third carbon atom in the pentane chain is attached to two identical substituents (methyl groups), which introduces symmetry and eliminates the potential for chirality.
Step-by-step explanation:
The molecule 3-chloro-3-methylpentane is not chiral because it contains a carbon atom that is bound to two identical groups. For a molecule to be chiral, it must have a carbon with four different substituents, leading to non-superimposable mirror images, or enantiomers. In 3-chloro-3-methylpentane, the carbon in question, which is the third carbon in the chain, is attached to two hydrogen atoms, a methyl group, and a chloro group. However, the presence of a second methyl group on this same carbon makes it symmetrical. Thus, this molecule has a plane of symmetry and cannot be chiral.
The structure of 3-chloro-3-methylpentane can be represented without the hydrogen atoms for clarity. This molecule would have a pentane backbone, with a chlorine atom and a methyl group both attached to the central (third) carbon. The doubling of the methyl group at this location prevents chirality as it introduces symmetry.
It is important to remember, based on VSEPR theory, that the geometry for a tetrahedral CH4 molecule has bond angles of 109.5°, which allows for the possibility of chirality if all four substituents are different. However, in the case of 3-chloro-3-methylpentane, this condition is not met due to the presence of two methyl groups attached to the third carbon.