Select ALL of the following statements that are true about the molecule SiCl4 (silicon tetrachloride): This molecule has NO net dipole. This molecule is nonpolar. This molecule contains polar bonds. This molecule has a molecular geometry of tetrahedral. This molecule has an electron geometry of octahedral. This molecule has an electron geometry of tetrahedral. This molecule is polar. This molecule has a molecular geometry of square planar. This molecule has a net dipole.
The Correct Answer and Explanation is:
✅ Correct Statements about SiCl₄ (Silicon Tetrachloride):
- ✅ This molecule has NO net dipole.
- ✅ This molecule is nonpolar.
- ✅ This molecule contains polar bonds.
- ✅ This molecule has a molecular geometry of tetrahedral.
- ✅ This molecule has an electron geometry of tetrahedral.
❌ Incorrect Statements:
- ❌ This molecule has an electron geometry of octahedral.
- ❌ This molecule is polar.
- ❌ This molecule has a molecular geometry of square planar.
- ❌ This molecule has a net dipole.
💡 Explanation
Silicon tetrachloride, SiCl₄, is a covalent molecule consisting of a central silicon atom bonded to four chlorine atoms. Each Si—Cl bond is polar because chlorine is more electronegative than silicon, creating a dipole in each bond.
However, the molecular geometry of SiCl₄ is tetrahedral, as determined by the VSEPR (Valence Shell Electron Pair Repulsion) theory. In this geometry, the four chlorine atoms are symmetrically arranged around the silicon atom with bond angles of approximately 109.5 degrees. Because of this perfect symmetry, the individual bond dipoles cancel each other out, resulting in no net dipole moment. That makes the entire molecule nonpolar, despite having polar bonds.
The electron geometry is also tetrahedral because silicon has four bonding pairs and no lone pairs. Electron geometry considers all electron domains (bonding and nonbonding), and in this case, all four domains are bonding pairs.
The option stating octahedral electron geometry is incorrect because that geometry is associated with six electron domains, which is not the case for SiCl₄. Similarly, square planar geometry applies to molecules with four bonding pairs and two lone pairs on the central atom, such as XeF₄. This is not applicable to SiCl₄.
In summary, SiCl₄ is a nonpolar molecule with polar bonds, a tetrahedral molecular and electron geometry, and no net dipole moment, which is typical for symmetric tetrahedral molecules.
