Draw the Lewis Structure then Answer the Four Questions to the Right.
Molecular Formula: GeF5
Hybridization of the central atom:
Electron geometry:
Molecular geometry:
Bond Angle(s) (list all if there are multiple):
The Correct Answer and Explanation is :
Lewis Structure of GeF5
To draw the Lewis structure for GeF5 (germanium pentafluoride), we follow these steps:
- Identify the central atom: The central atom is germanium (Ge), which is in Group 14, so it has 4 valence electrons.
- Determine the number of valence electrons: Each fluorine (F) atom belongs to Group 17, so each fluorine atom has 7 valence electrons. Since there are 5 fluorine atoms, the total number of valence electrons is ( 5 \times 7 = 35 ) electrons from fluorine atoms, plus 4 electrons from the germanium atom, for a total of 39 valence electrons.
- Distribute the electrons: Place germanium (Ge) in the center and arrange the five fluorine atoms around it. Each Ge-F bond requires two electrons, so we use 10 electrons for the 5 bonds. The remaining 29 electrons are distributed as lone pairs around the fluorine atoms.
- Check formal charges and bonding: Fluorine atoms, with 3 lone pairs and 1 bond to Ge, have 8 electrons around them, fulfilling the octet rule. Ge has 5 bonds and no lone pairs, which is an acceptable configuration.
The resulting Lewis structure places Ge in the center with five single bonds to fluorine atoms. There are no lone pairs on the germanium atom, and each fluorine atom has three lone pairs.
Answer to the Four Questions:
- Hybridization of the central atom:
- The central germanium atom has five bonding regions (one for each Ge-F bond). The hybridization is sp³d because there are five regions of electron density (one for each bond), and this corresponds to the sp³d hybridization.
- Electron geometry:
- With five bonding regions around the central atom, the electron geometry is trigonal bipyramidal. This geometry describes how the electron clouds are arranged around the central atom.
- Molecular geometry:
- The molecular geometry is also trigonal bipyramidal since there are no lone pairs on the central atom to alter the molecular shape.
- Bond Angle(s):
- In a trigonal bipyramidal arrangement, there are two distinct bond angles:
- The equatorial bond angles (the bonds in the plane around the central atom) are approximately 120°.
- The axial bond angles (the bonds above and below the plane) are approximately 90°.
Explanation:
- Hybridization: The germanium atom in GeF5 forms five sigma bonds with fluorine atoms. To accommodate these five bonds, the germanium atom undergoes sp³d hybridization, mixing one s orbital, three p orbitals, and one d orbital to form five equivalent hybrid orbitals.
- Electron Geometry: With five bonding regions and no lone pairs, the electron geometry is trigonal bipyramidal. This is because the electron pairs arrange themselves to minimize repulsion in a five-position arrangement.
- Molecular Geometry: Since there are no lone pairs on the central atom, the molecular geometry is the same as the electron geometry, trigonal bipyramidal.
- Bond Angles: In trigonal bipyramidal geometry, the axial positions (up and down) are at 90° from the equatorial positions (in the plane). The equatorial positions are 120° apart, ensuring minimal repulsion between electron pairs.