In this article we are going to discuss about socl2 lewis structure including its drawing, hybridization, shape, formal charges, electron pairs and some important facts regarding socl2.
SOCl2 is commonly known as thionyl chloride. It is toxic in nature. Socl2 has no color which is volatile as well pungent in nature. It is generally used as a chlorinating agent which converts alcohols into chlorides. SOCl2 reacts with water to produce sulphur dioxide and hcl. It has the molecular weight of 118.94 gm/mol.
SOCl2 Lewis Structure Drawing
In socl2 lewis structure we see that as S has larger size and also less electronegative than other atoms it works as central atom in socl2.
Sulphur has 6 electrons in the outermost shell out of which 4 electrons participate in sigma bonding with 2 cl atoms and 1 O atom. With O atom S forms 1 sigma and 1 Pi bond. There is 1 electron pair that still present on central S atom which present as a electron pair on sulphur atom.
O has 6 electrons in the valance shell out of those only 2 are used for the formation of sigma and pi bonding and that 4 existing electrons present as lone pair of electrons on O. In cl 7 valance electron present out of which only 1 electron is take part in sigma bonding formation and those existing 6 electrons present as 3 nonbonding electron pairs.
SOCl2 Lewis Structure Shape
From VSEPR theory we see that the geometry of socl2 is trigonal pyramidal. In this structure central sulphur atom is surround by 2 cl atoms and 1 lone pair in tetrahedral manner. As one lone pair present in the central S atom the true tetrahedral shape becomes distorted.
If we consider, the lone pair of electron is absent in socl2 the geometry is actual tetrahedral but as we seen 1 lone pair of electron is present on central sulphur atom, the real td structure does not occur and the actual shape becomes pyramidal.
SOCl2 Lewis Structure Formal Charges
The formal charge on particular atoms in socl2 compound can be estimated by using the formula given below:
Formal Charge (f) =NV.E-NB.E/2-NN.E
Where,
NV.E =Total No of valance electrons, NB.E = Total No of bonding electrons,
NN.E= Total No of nonbonding electrons.
Hence formal charge on central S atom in socl2=6-8/2-2=0.
Formal charge on double bonded O atom in socl2=6-4/2-4=0.
Formal charge on cl atoms in socl2=7-2/2-6=0.
Hence formal charge on central S atom is 0 and each cl atom and also O atom has 0 formal charges, making the whole compound is electrically neutral.
SOCl2 lewis Structure Lone Pairs
The electrons that present in the valance shell of an atom that don’t participate in bonding with similar or another atom is called as lone pair of electron or nonbonding electrons.
The lone pairs on particular atoms in socl2 compound can be estimated by using the formula given below:
No of lone pair of electron on any atom= maximum no of valance electron of the atom-no of bonds that formed by that particular atom.
In socl2 lone pair present on central S atom= 6-4=2 i.e. 1 lone pair of electron.
Lone pair present on double bonded O atom in socl2=6-2=4 i.e. 2 lone pairs.
Lone pair present on Cl atoms in socl2= 7-1=6 i.e.3 lone pair of electron.
These lone pairs on s,cl,o atoms are given in the socl2 lewis structure as electron dots.
SOCl2 Hybridization
Hybridization is a method in which different energy atomic orbitals are mixed to produce an equal number of hybrid orbitals having same energy.
The electronic configuration of S atom in the valance shell is 3s2 3p4. In the ground state of S atom we see that there are only 2 unpaired electrons and to form socl2, 3 unpaired electrons are needed. In the excited state S send its 1 3p electron into 3d orbital making a total of 4 unpaired electrons.
2 Cl give 1 unpaired electron to form 2 S-Cl bonds and 1 O give 1 unpaired electron to form S-O sigma bond and remaining unpaired electron of O form S=O (pi) bond. In socl2, S uses sp3 hybrid orbital to make S-Cl and S=O bonds. According to sp3 hybridization the geometry should be Tetrahedral but the actual shape is pyramidal.
SOCl2 lewis Structure Resonance
Resonance is an empirical method in which electron pair shifting occurs from one atom to another atom by delocalization of electron and the structure we get by this process is defined as resonating or canonical structure.
Socl2 have 3 resonating structure in which each s-cl bond gets partial double bond character by the process in which nonbonding electrons on Cl atom is in conjugation with the vacant ∏* antibonding orbital of S=O bond.
SOCl2 lewis structure Octet Rule
When we see the lewis structure of socl2 we find that each chlorine atom has 8 electrons in the valance shell and satisfy their octet. In socl2 compound S forms 2 S-Cl bonds and 1 S=O bond, also there is 1 lone pair of electron that present on central S atom making a total of 10 electrons around central S atom.
As S is a part of 3rd period in the periodic table, sulphur atom can expand their octet which contains more than 8 electrons. Hence socl2 is a stable compound in terms of octet rule.
SOCl2 Polar Or Nonpolar?
SOCl2 is a polar compound. In SOCl2 S=O bond moment lies towards O atom, because O is more electronegative than S atom. 2 S-Cl bond moments lies towards more electronegative Cl atom.
All these bond moments lies in the same direction which makes the compound polar. The overall dipole moment od of socl2 is 1.44 Debye.
SOCl2 Uses
- It is an important reagent for converting alkyl alcohols to alkyl halide through SN1 mechanism.
- It is used for the preparation of acyl chloride from carboxylic acid.
- As socl2 is a polar aprotic solvent which stabilises cations only. It is used as a solvent in SN2 reaction.
- SOCl2 is used in lithium-thionyl chloride batteries. In these batteries it is used as positive electrodes.
- SOCl2 is used as a reducing agent for the EPR detection of Tc(6) compounds.
By considering the above facts we see that socl2 is a polar covalent compound which has pyramidal shape in which central S uses sp3 hybrid orbital.
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Hi….I am Susanta Maity. I have completed my Masters from Vidyasagar university with a specialization in organic chemistry.
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