Total Valence Electrons: 34 Rough Lewis Structure: TeF4 Molecular Geometry / Electron-Group Geometry: See-saw/trigonal bipyramidal Formula: #-Te_E Solubility: More soluble in hexane or water? Bond Polarity (AEN): Te – F = 2.1 4.0 = 1.9 Molecule Polarity: water
The Correct Answer and Explanation is:
Correct Answers:
- Total Valence Electrons: 34
- Rough Lewis Structure:
Central atom: Te (Tellurium)
Four single bonds to F atoms and one lone pair on Te - Molecular Geometry / Electron-Group Geometry:
- Molecular Geometry: See-saw
- Electron-Group Geometry: Trigonal bipyramidal
- Formula: TeF₄
- Solubility: More soluble in water
- Bond Polarity (ΔEN):
ΔEN = |4.0 (F) – 2.1 (Te)| = 1.9 - Molecule Polarity: Polar
Explanation
Tellurium tetrafluoride (TeF₄) is a molecule consisting of a central tellurium atom bonded to four fluorine atoms. To determine the number of valence electrons, we sum the valence electrons of tellurium (6 valence electrons from Group 16) and fluorine (7 valence electrons from Group 17):
- Te: 6 electrons
- F: 4 × 7 = 28 electrons
- Total = 6 + 28 = 34 valence electrons
In the Lewis structure, tellurium is the central atom with four single bonds to fluorine atoms and one lone pair. This results in five electron regions (4 bonding pairs + 1 lone pair), giving it a trigonal bipyramidal electron-group geometry. However, because one of those regions is a lone pair, the molecular geometry is see-saw.
Fluorine is much more electronegative (4.0) than tellurium (2.1), making each Te–F bond polar, with a significant electronegativity difference of 1.9. Since the molecular shape is asymmetrical due to the lone pair, the individual bond dipoles do not cancel out. Therefore, TeF₄ is a polar molecule.
In terms of solubility, polar molecules tend to dissolve better in polar solvents, following the principle “like dissolves like.” Water, being highly polar, is a better solvent for TeF₄ than hexane, a nonpolar solvent. Thus, TeF₄ is more soluble in water than in hexane.
In summary, TeF₄ has 34 valence electrons, a see-saw molecular geometry, polar bonds, and an overall polar structure, making it more soluble in polar solvents like water.
