Final answer:
PH3 has a trigonal pyramidal structure, PH4+ is tetrahedral, and XeF2 is linear. These structures are explained by the VSEPR theory, considering the arrangement of bonding pairs and lone pairs of electrons to understand the geometry and chemical bonding in molecules.
Step-by-step explanation:
When discussing the molecular structure of compounds, it is important to consider the chemical bonding and molecular geometry that dictate the shape and polarity of the molecule. Here, I will describe the molecular structures for PH3, PH4+, and XeF2 as examples.
- PH3: PH3, or phosphine, has a trigonal pyramidal molecular structure with phosphorus as the central atom surrounded by three hydrogen atoms. It has one lone pair of electrons on the phosphorus, which affects the molecular geometry making the bond angles slightly less than the ideal 109.5° found in a perfect tetrahedron.
- PH4+: The PH4+ ion, or phosphonium ion, has a tetrahedral molecular structure. All four positions around the central phosphorus atom are occupied by hydrogen atoms, and there are no lone pairs on the central atom.
- XeF2: Xenon difluoride (XeF2) features a linear molecular structure. It has three lone pairs and two bonding pairs of electrons, which arrange themselves in a way that XeF2 takes on a linear shape to minimize repulsions.
To understand these structures in detail, one analyzes the bonding and electron pair repulsions according to VSEPR (Valence Shell Electron Pair Repulsion) theory. By examining Lewis structures and electron pair geometry, we can predict the three-dimensional layout of the molecules.