The molecules
have the same molecular formula (C3H8O) but different chemical structures. (b) Which molecule do you expect to have a larger dipole moment? [Sections 11.2 and 11.5]

Key Concepts

Molecular Formula vs. Structural Isomers

Molecular formulas represent the types and numbers of atoms in a molecule, but they do not convey how those atoms are arranged. Structural isomers are compounds that share the same molecular formula but differ in the connectivity of their atoms, leading to different chemical and physical properties. Understanding this distinction is crucial for analyzing how structural differences can affect molecular behavior.

Dipole Moment

The dipole moment is a measure of the separation of positive and negative charges in a molecule, indicating its polarity. It is influenced by the molecular geometry and the electronegativity of the atoms involved. Molecules with significant differences in electronegativity between bonded atoms and asymmetrical shapes typically exhibit larger dipole moments, making this concept essential for predicting molecular interactions.

Electronegativity and Molecular Geometry

Electronegativity refers to the ability of an atom to attract electrons in a bond, which affects the distribution of electron density in a molecule. The geometry of a molecule, determined by the arrangement of its atoms, influences how these charges are distributed. Together, electronegativity and geometry help predict the overall dipole moment, as asymmetrical arrangements of polar bonds can lead to a net dipole.