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

For a molecule with 4 electron domains and 3 bonding pairs, the electron domain geometry is indeed tetrahedral. This classification arises from the presence of four regions of electron density around the central atom, which can be created from single bonds, double bonds, triple bonds, or lone pairs.

In this scenario, the presence of 3 bonding pairs suggests that three of these electron domains are involved in bonding with other atoms, while the fourth domain likely accommodates a lone pair of electrons. According to VSEPR (Valence Shell Electron Pair Repulsion) theory, the arrangement of the four electron domains will adopt a geometry that minimizes the repulsion between them. The ideal shape for four electron domains is a tetrahedron, where the bond angles are approximately 109.5 degrees.

The distinction lies in the resultant molecular geometry, which, in this case, would be trigonal pyramidal due to the presence of the lone pair that affects the spatial positioning of the bonded atoms. However, when asked about electron domain geometry specifically, the answer maintains tetrahedral as the correct classification, as it applies to the arrangement of all electron regions around the central atom.