Use VSEPR theory to predict the electron-pair geometry and the molecular geometry of XeF5+.
Electron-pair geometry = square pyramidal; molecular geometry = trigonal bipyramidal
Electron-pair geometry = trigonal bipyramidal; molecular geometry = see-saw
Electron-pair geometry = trigonal bipyramidal; molecular geometry = trigonal bipyramidal
Electron-pair geometry = octahedral; molecular geometry = trigonal bipyramidal
Electron-pair geometry = octahedral; molecular geometry = square pyramidal
The Correct Answer and Explanation is :
The correct answer is:
Electron-pair geometry = octahedral; molecular geometry = square pyramidal.
Explanation:
The VSEPR (Valence Shell Electron Pair Repulsion) theory helps predict the shapes of molecules by considering electron pairs around a central atom. In this case, the molecule is XeF₅⁺, which is a xenon pentafluoride cation.
- Determine the electron pairs around the central atom:
- Xenon (Xe) is in Group 18 and thus has 8 valence electrons.
- Each fluorine atom contributes 1 electron, and since there are 5 fluorine atoms, this adds 5 electrons to the valence shell of xenon.
- The cation (XeF₅⁺) means it has lost one electron, so the total electron count around xenon is:
- 8 (from Xe) + 5 (from F atoms) – 1 (due to the +1 charge) = 12 electrons.
- These 12 electrons will be arranged into pairs, and the xenon will have 6 electron pairs (since 12 ÷ 2 = 6).
- Electron-pair geometry:
- With 6 electron pairs, the ideal arrangement is octahedral, as this minimizes the repulsion between electron pairs.
- Molecular geometry:
- In the case of the molecular geometry, we focus on the positions of the atoms, not the electron pairs.
- Since there are 5 fluorine atoms and 1 lone pair (from the remaining electron), the molecular geometry will be square pyramidal. The 5 fluorine atoms occupy the corners of the square base, and the lone pair occupies the apical position, distorting the geometry from a perfect octahedron to a square pyramid.
The electron-pair geometry is octahedral, and the molecular geometry, due to the lone pair, is square pyramidal.
I will now generate an image illustrating this structure.
Here is an image representing the octahedral structure of XeF₅⁺, showing the square pyramidal molecular geometry. You can see how the 5 fluorine atoms are arranged in a square base, with one lone pair occupying the apical position, resulting in this particular molecular geometry.
