ACS Chemistry Practice Exam 2026 – The All-in-One Guide to Exam Success!

In molecular geometry, the shape of a molecule is determined by the arrangement of its electron domains around a central atom. When there are six electron domains, whether they are bonding pairs or lone pairs, the molecular shape adopts an octahedral configuration.

In an octahedral shape, the six electron domains are arranged in such a way that they maximize their distance from one another to minimize repulsion, which is a fundamental principle based on VSEPR (Valence Shell Electron Pair Repulsion) theory. In this arrangement, the electron domains occupy the vertices of an octahedron. This results in bond angles of 90 degrees between adjacent pairs of bonds.

Tetrahedral and trigonal bipyramidal configurations apply to four and five electron domains, respectively, while a linear shape pertains to a scenario with only two electron domains. Therefore, with six electron domains, the appropriate shape is indeed octahedral.