Is SiCl₄ polar or nonpolar?

The SiCl₄ is a non-polar molecule.

Polarity in molecules arises from the separation of partial charges due to the electronegativity difference of two atoms in a molecule. Atoms such as N, O, and F are more electronegative relative to other atoms in the periodic table. These atoms tend to have a partial negative charge when bonded to less electronegative atoms. Some atoms on the left of the periodic table are considered to have low electronegativity values that, if covalently bonded to electronegative atoms, produce a partial positive charge. The separation of partial charges produces a dipole moment in the molecule. A molecule is considered a polar molecule if the polar bonds results in a net dipole moment while a molecule is considered non-polar molecule if the atoms have equal to small electronegativity difference or if the dipole moments in the polar bonds cancel out (no net dipole moment).

The SiCl₄ molecule contains 4 polar bonds wherein the Si atom has the partial positive charge while the Cl atoms have the partial negative charges. Cl atom is more electronegative than Si, thus Cl atoms have partial negative charges and Si has a partial negative charge. Considering that the molecule has a tetrahedral structure, all the dipole moments from the Si-Cl polar bonds will cancel thus the molecule has no net dipole moment. A dipole moment is denoted by ? where the tail of the arrow is the partial positive pointing to partial negative atom.

For the SiCl₄ molecule,

The net dipole moment of the three dipole moments pointing down and the dipole moment pointing up cancel thus giving zero net dipole moment. Molecules with zero net dipole moment are non-polar molecules.

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