Draw the Lewis structure for XeF4 in the window below and then answer the questions that follow. Do not include overall ion charges or formal charges in your drawing
D What is the electron-pair geometry for Xe in XeF4?
What is the the shape (molecular geometry) of XeF42
The Correct Answer and Explanation is :
Xenon tetrafluoride (XeF₄) is a chemical compound where a xenon (Xe) atom is centrally bonded to four fluorine (F) atoms. To determine its electron-pair geometry and molecular geometry, we can apply Valence Shell Electron Pair Repulsion (VSEPR) theory.
Electron-Pair Geometry:
- Determine the Total Number of Valence Electrons:
- Xenon (Xe) is a noble gas in Group 18, contributing 8 valence electrons.
- Each fluorine (F) atom, a halogen in Group 17, contributes 7 valence electrons.
- Total valence electrons = 8 (from Xe) + 4 × 7 (from F) = 36 electrons.
- Construct the Lewis Structure:
- Place the xenon atom at the center.
- Form single bonds between xenon and each fluorine atom, utilizing 8 electrons (4 bonds × 2 electrons per bond).
- Distribute the remaining 28 electrons as lone pairs:
- Each fluorine atom receives three lone pairs, accounting for 24 electrons (4 × 6 electrons per F).
- The xenon atom retains two lone pairs, utilizing the remaining 4 electrons.
- Apply VSEPR Theory:
- The xenon atom has six regions of electron density: four bonding pairs (from the F atoms) and two lone pairs.
- According to VSEPR theory, six regions of electron density arrange themselves in an octahedral geometry to minimize electron pair repulsion.
Molecular Geometry:
- Electron-Pair Geometry: Octahedral
- Molecular Geometry: Square Planar
In the octahedral arrangement, the lone pairs occupy two of the six positions, typically placed opposite each other to minimize repulsion. The four fluorine atoms occupy the remaining four positions, forming a square planar shape.
Explanation:
The square planar geometry arises because the lone pairs, while occupying positions in the octahedral arrangement, do not contribute to the molecular shape. The fluorine atoms are positioned at the four corners of a square, with 90° bond angles between them. This arrangement minimizes electron pair repulsion, adhering to the principles of VSEPR theory.
For a visual representation and a more detailed explanation, you might find the following video helpful:
videoXeF4 Molecular Geometry, Bond Angles & Electron Geometryturn0search0