Question

What is the geometric structure of the \(\mathrm{SiF}_{4}\) molecule? How many pairs of valence electrons are present on the silicon atom of \(\mathrm{SiF}_{4} ?\) What are the approximate \(\mathrm{F}-\mathrm{Si}-\mathrm{F}\) bond angles in \(\mathrm{SiF}_{4} ?\)

Short answer

The $\mathrm{SiF}_{4}$ molecule has a tetrahedral molecular geometry. The silicon atom has 4 pairs of valence electrons, and the approximate $\mathrm{F}-\mathrm{Si}-\mathrm{F}$ bond angles are 109.5°.

Step-by-step solution

Determine the Lewis structure of SiF_4

To find the Lewis structure of the SiF_4 molecule, follow these steps: 1. Count the total number of valence electrons: Silicon (Si) has 4 valence electrons, and each fluorine (F) atom has 7 valence electrons, making a total of 4 + 4(7) = 32 valence electrons. 2. Place the central atom (Si) in the center and arrange the F atoms around it, forming single bonds: Si - F - F | | F - Si - F 3. Distribute the remaining valence electrons to complete the octet rule: Each fluorine atom needs 6 more electrons (three lone pairs) to complete its octet. There are no remaining electrons for the silicon atom, but since it is bonded to 4 fluorine atoms, its octet is also complete.

Determine the molecular geometry

Using the VSEPR theory, we can determine the molecular geometry of SiF_4: 1. Identify the central atom's electron pair geometry: The silicon atom is surrounded by 4 bonding electron pairs (each F-Si single bond), which results in a tetrahedral electron pair geometry. 2. Identify the molecular geometry: Since there are no lone pairs of electrons on the silicon atom, the molecular geometry is also tetrahedral.

Find the number of valence electron pairs on the silicon atom

The silicon atom has 4 pairs of valence electrons, corresponding to its 4 single bonds with the fluorine atoms.

Calculate the F-Si-F bond angles

In a tetrahedral molecular geometry, the bond angles are approximately 109.5°. So, the F-Si-F bond angles in SiF_4 are about 109.5°. To sum up, SiF_4 has a tetrahedral molecular geometry, the silicon atom has 4 pairs of valence electrons, and the F-Si-F bond angles are approximately 109.5°.