Final answer:
The molecular geometry for an atom with octahedral electron-pair geometry can be square pyramidal if it has four single bonds, a double bond, and a lone pair, as with XeOF4.
Step-by-step explanation:
When determining the correct molecular geometry for atoms in a molecule, we need to consider the electron-pair geometry. The electron-pair geometry is based on the number of regions of electron density around the central atom. Octahedral geometry occurs when there are six regions of electron density. An example is a molecule with four single bonds, a double bond, and a lone pair, leading to an octahedral electron-group geometry and a square pyramidal molecular structure. The molecule XeOF4 adopts this structure. The valence shell electron pair repulsion (VSEPR) theory is employed to minimize repulsions between these electron pairs to determine the shape.
In an environment with octahedral electron-pair geometry, when lone pairs are present, the molecular structure can change to accommodate these pairs in the most favorable position, sometimes leading to structures like square pyramidal or square planar forms depending on the number of lone pairs.