Is SiCl4 Polar or Nonpolar?

Answer: SiCl4 (Silicon Tetrachloride) is a nonpolar molecule because all of the four chlorine molecules are equally spaced around the central silicon atom in a tetrahedral structure. 

As the electronegativity difference between chlorine (3.16) and silicon (1.90) is quite high, the bonds within the molecule are polar covalent. However, since the molecules on the outside are all the same these charges eventually cancel out when considering the polarity of the entire molecule. 

However the nature of the polar covalent and the large number of halides on the molecule does create partial charges within the molecule. In this scenario the chlorine receives a partial negative charge and the silicon gets a partial positive charge. As a result SiCl4 is a liquid with a boiling point of approximately 60˚C (this video details how to create SiCl4 in a chemistry lab although this is NOT recommended as the substance is toxic). This effect is similar to that for SiF4 (learn more about this molecule in this article). 

SiCl4 Ball and Stick Model
SiCl4 Ball and Stick Model. Created with MolView.
How is SiCl4 utilized in the real world?

Oftentimes SiCl4 is utilized as an intermediate in order to extract the Silicon. Therefore, it is unsurprising that it finds many uses in advanced technological applications including fiber optic cables and solar cells for solar panels.

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