Silicon Tetrachloride (SiCl4) Lewis Structure and Steps of Drawing
Silicon tetrachloride (SiCl4) is an inorganic volatile compound at room temperature. There are four chlorine atoms and one silicon atom in SiCl4 molecule. Lewis structure of SiCl4 contains four Si-Cl bonds. Silicon atom is located as the center atom and each chlorine atom has 3 lone pairs in their valence shell. We will learn how to draw the lewis structure of SiCl4 step by step in this tutorial.
SiCl4 lewis structure
According to the lewis structure of SiCl4, you can see how chlorine atoms are connected with center atom, silicon. There are only single bonds between chlorine atoms and silicon atom. As well, there are no charges on atoms and SiCl4 does not have an overall charge. Each chlorine atom has three lone pairs in their valence shells and silicon atom does not have lone pairs in it's valence shell.
Silicon tetrachloride (CCl4)
Silicon tetrachloride is a volatile liquid inorganic compound. In the presence of water, it decomposes to hydrochloric acid.
Steps of drawing lewis structure of SiCl4
There are several steps to complete the lewis structure of SiCl4. Each step of drawing is explained in detail in this tutorial.
- Find total number of electrons of the valance shells of silicon atom and chlorine atoms
- Determine total electrons pairs as lone pairs and bonds
- Find center atom and draw basic skeletal structure
- Mark lone pairs on atoms
- Mark charges on atoms if there are charges.
- Check the stability and minimize charges on atoms by converting lone pairs to bonds to obtain best lewis structure.
Total number of electrons of the valance shells of SiCl4
There are only two elements in SiCl4 molecule; silicon and chlorine.
- Chlorine is a group VIIA element in the periodic table and contains 7 electrons in its last shell.
- Silicon atom has 4 electrons in its last shell because it is a IV group element. Now we know how many electrons are included in valence shells of each atom.
- valence electrons given by silicon atom = 4 * 1 = 4
- valence electrons given by chlorine atoms = 7 * 4 = 28
- Total valence electrons = 4 + 28 = 32
Total valence electrons pairs
Total valance electrons pairs = σ bonds + π bonds + lone pairs at valence shells
Total electron pairs are determined by dividing the number total valence electrons by two. For, SiCl4, total pairs of electrons are 16 (32/2) in their valence shells.
Center atom selection and draw basic skeletal of CCl4
To be the center atom, ability of having greater valance and being most electropositive element in the molecule are important facts.
Because, SiCl4 is a simple molecule, it is not very difficult to select the center atom.
- Considering greater valence - Chlorine's highest valence is 7 and silicon's highest valence is 4. From that case, we can suggest that chlorine has the potential to be the center atom.
- Most electropositive element - Silicon's electronegativity is 1.9 and chlorine's electronegativity is 3.16 according to the Pauling's electronegativity scale. Therefore, silicon is more electropositive than chlorine. In that case, we can suggest that carbon has the potential to be the center atom.
- Now, there is a confusion between how to select the center atom.
- Now, we are going to consider the minimum valence of chlorine and silicon atoms to form stable compounds.
- Chlorine's minimum valence is 1 and silicon's minimum (only) valence is 4. That means, there should be minimum number of four bonds around silicon atom, if silicon form a stable compound.
- From above finding, we understand that silicon atom should be the center atom and basic skeletal structure can be drawn as below.
Mark lone pairs on atoms
After deciding the center atom and drawing of skeletal structure of SiCl4 molecule, we can start to mark lone pairs on atoms. Remember that, there are total of 16 electron pairs to mark on atoms as bonds and lone pairs.
- There are already 4 single bonds in the above drawn skeletal structure. Now only 12 (16-4) electron pairs are remaining to mark on atoms.
- Usually, those remaining electron pairs should be started to mark on outside atoms.
- Therefore, mark those electrons pairs on each chlorine atom; One chlorine atom will 3 lone pairs. So all remaining 12 lone pairs are marked on all four chlorine atoms.
Mark charges on atoms if there are and check the stability and minimize charges on atoms by converting lone pairs to bonds
There are no charges on silicon and chlorine atoms and we do not need to the step of reducing charges of atoms. It means that, we have obtained the lewis structure of silicon tetrachloride.
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