Determine the electron geometry (eg) and molecular geometry (mg) of XeF
The correct answer and explanation is :
The molecule XeF₄ (xenon tetrafluoride) has the following electron geometry (eg) and molecular geometry (mg):
- Electron Geometry (eg): Octahedral
- Molecular Geometry (mg): Square planar
Explanation:
- Determine the Central Atom and Bonding: Xenon (Xe) is the central atom in XeF₄, and it forms bonds with four fluorine (F) atoms. Since fluorine is highly electronegative, each fluorine atom forms a single bond with the xenon atom. Therefore, XeF₄ has 4 bonding pairs around the central xenon atom.
- Determine Electron Pairs Around the Central Atom: Xenon belongs to Group 18 of the periodic table, so its electron configuration is [Kr] 4d¹⁰ 5s² 5p⁶. When it bonds with four fluorine atoms, it utilizes its 4 valence electrons to form bonding pairs. However, xenon has a full valence shell and can expand its octet, meaning it can hold more than eight electrons in its valence shell. In XeF₄, xenon has 4 bonding pairs and 2 lone pairs of electrons. This gives a total of 6 electron pairs around the central atom.
- Electron Geometry (eg): Since there are 6 electron pairs (4 bonding pairs and 2 lone pairs) around the central atom, the electron geometry of XeF₄ is octahedral. This geometry involves six regions of electron density arranged symmetrically around the central atom.
- Molecular Geometry (mg): To determine the molecular geometry, we need to consider only the positions of the atoms, not the lone pairs. The lone pairs of electrons are positioned to minimize repulsion, which causes them to occupy opposite positions in the octahedral arrangement. The four fluorine atoms are positioned in a square planar arrangement, with 90° bond angles between them. Thus, the molecular geometry of XeF₄ is square planar.
Conclusion:
- Electron Geometry (eg): Octahedral (6 electron pairs)
- Molecular Geometry (mg): Square planar (4 bonding pairs and 2 lone pairs)