What is the electron-pair geometry for P in PF2Cl3? There are lone pair(s) around the central atom, so the molecular geometry (shape) of PF2Cl3 is
The Correct Answer and Explanation is:
For the molecule PF2Cl3, we need to analyze its electron-pair geometry and molecular geometry based on the arrangement of bonding pairs and lone pairs around the central phosphorus atom (P).
- Electron-pair geometry:
- Phosphorus (P) is the central atom, and it is surrounded by 5 regions of electron density—3 bonds with chlorine atoms (Cl), 2 bonds with fluorine atoms (F), and potentially one or more lone pairs of electrons.
- According to the valence shell electron pair repulsion (VSEPR) theory, when there are five regions of electron density, the electron-pair geometry is trigonal bipyramidal.
- Molecular geometry (shape):
- In PF2Cl3, phosphorus forms 5 bonds (3 Cl atoms and 2 F atoms) and has no lone pairs (since phosphorus has a valence of 5, and all are used in bonding).
- The molecular geometry, or shape, depends on how the atoms are arranged in the trigonal bipyramidal geometry. Because there are no lone pairs, the shape will be trigonal bipyramidal as well.
- The 3 Cl atoms and 2 F atoms will occupy the positions around the phosphorus atom in this trigonal bipyramidal geometry. The chlorine atoms will likely occupy the equatorial positions (as they are larger and more electronegative), while the fluorine atoms will occupy the axial positions.
Explanation:
The VSEPR theory predicts that the electron pairs around the central phosphorus atom in PF2Cl3 will arrange themselves to minimize electron-electron repulsion, which results in a trigonal bipyramidal electron-pair geometry. Since there are no lone pairs on phosphorus in this case, the molecular geometry remains the same as the electron-pair geometry, which is trigonal bipyramidal. The specific arrangement of atoms in this geometry helps explain the molecule’s shape and the spatial orientation of the substituents.
