Final answer:
VSEPR theory explains how valence-electron pairs arrange themselves to minimize repulsion and predict molecular structures and bond angles.
Step-by-step explanation:
When considering how valence-electron (bonding and nonbonding) pairs arrange themselves to achieve areas of least repulsion, the concept in question is the VSEPR theory.
The Valence Shell Electron Pair Repulsion (VSEPR) theory posits that electron pairs within the valence shell of a central atom will arrange in a way that minimizes repulsion, thus maximizing the distance between them. This includes both bonding pairs of electrons, which form part of the chemical bonds between atoms, and lone pairs, which are not involved in bonding but still contribute to the electron density around an atom. According to VSEPR theory, these arrangements lead to predictable molecular structures and bond angles.