At normal temperature, sulphur dichloride is a red viscous liquid. It has a strong chlorine odour to it. It forms chlorine-containing acids when it combines with water.
SCl2 is a very corrosive and poisonous chemical. Because the electronegativity difference between S and Cl is not large, it is a covalent molecule. They are both non-metals. The oxidation states of S and Cl are +2 and -1, respectively.
Hexane, benzene, carbon tetrachloride, and other solvents are all soluble in it.
SCl2 is unstable and, as demonstrated, is in equilibrium with S2Cl2.
SCl2 is used to make SOCl2, S4N4, S3H2, and other sulphur compounds.
The ideas of Lewis dot structure, hybridization, and polarity will be discussed in this article.
We’ll also learn how to use VSEPR theory to determine the geometry and form of a covalent compound.
Lewis Structure SCl2
One of the most fundamental methods for determining the type of link between atoms is the Lewis structure, often known as the Lewis dot structure.
The valence shell electrons are represented by dots in this manner, and two dots on distinct elements can be connected to form a single bond.
It’s a two-dimensional illustration of bonding. It does not explain all of the features, but it does provide some important information on the molecule in question.
The method of drawing the Lewis structure is a hit-or-miss approach.
The octet rule and formal charges should be satisfied in the final Lewis structure. If neither of them are satisfied, another Lewis structure is drawn and examined for both.
The Rule of the Octet
S and p block elements, collectively referred to as main group elements, follow the octet rule.
All of the elements want to be stable. Because of their fully-filled structure, noble gases are considered inert and stable.
To achieve a noble gas-like configuration, all other elements seek to fill their valence shell completely with electrons.
There are 8 electrons in a fully filled valence shell arrangement (like that of noble gas).
It has 8 electrons since the ns and np subshells are totally occupied. (6 from np, 2 from ns). The octet rule is satisfied when there are 8 electrons in the outermost shell.
Charge Formal
When a compound’s net charge is zero, it does not imply that the charge in all of the compound’s constituents is also zero.
When the charge of the molecule is dispersed among the atoms, a formal charge develops on a specific atom.
It’s a purely theoretical idea.
This is useful for determining the proper and lowest-energy Lewis Structure. It’s calculated with the following formula:
How to Draw the Lewis Structure of SCl2 in Steps
Step 1: Count the total number of electrons in the valence shell of the chemical.
This is accomplished by adding all of the constituent atoms’ valence shell electrons.
We deduct the charge from the sum of valence shell electrons if the compound is positively charged, and we add the charge to the sum of valence shell electrons if the compound is negatively charged.
Atomic Number Atomic Number Atomic Number Atomic Number Atomic Number Atomic Number Atom
According to group number, valence electrons
Configuration of electronic devices (E.C.)
E.C.’s Valence Shell
E.C.’s valence electrons
One
S
6 16 16 6
3s2 3p4 n=3 6 1s2 2s2 2p6
Two
Cl
17 17 (7)
3s2 3p5 n=3 7 1s2 2s2 2p6
The total number of electrons in the valence shell is 6 + (7*2) =20.
For S and Cl, the Lewis dot structure is as follows:
Step 2: Pick a good core atom for your chemical.
Out of the constituent atoms, the central atom is the least electronegative.
The electron density of the core atom is meant to be shared by all other atoms.
The central atom will not share the electron density with the side atom if the central atom is more electronegative.
As a result, the core atom in this molecule is S.
Step 3: Sketch down a skeleton diagram.
In this phase, we must properly organise the side and central atoms.
Step 4: Arrange the valence electrons around the symbol of the element.
Bond formation is used to put the entire valence shell electrons (calculated in step 1).
Step 5: Form bonds to complete the octet of atoms.
In its isolated state, each Cl atom contains seven valence electrons. To complete the octet, it shares one electron with S.
In its isolated state, S possesses six valence electrons.
To complete the octet, it borrows one electron from both Cl atoms.
Step 6: Determine all atoms’ formal charges.
This chemical has a net charge of zero. As a result, the total formal charge on three atoms should equal zero.
Atom
In a free atom, the total number of valence electrons is
Formal Charge*0.5 Total amount of lone pairs (Total number of bonding electrons)
6 2 80.5=4 S 6 2 80.5=4 S 6 2 8*0.5=4
6-2-4=0
Cl1 7 3 80.5=4 Cl1 7 3 80.5=4 Cl1 7 3 8*0.5
7-3-4=0
Cl2 7 3 80.5=4 Cl2 7 3 80.5=4 Cl2 7 3 8*0.5
7-3-4=0
As a result, the Lewis structure drawn in step 5 is the best for SCl2. You can watch this video for a better understanding.
Geometry of SCl2
The 3D arrangement of atoms and bonds in a compound is referred to as geometry. The geometry can be modified by some lone pairs, and the distorted arrangement is known as shape.
The Lewis Structure can tell us about the types of bonds, but it can’t tell us about their geometry or shape.
For covalent molecules, the VSEPR theory has overcome this issue. The valence shell electron pair repulsion theory is referred to as VSEPR theory.
• Because the valence electron pairs resist each other, the system becomes unstable.
• To make the electron configuration stable, the repulsions between them must be reduced.
• As a result, electrons align themselves with the least amount of repulsion and the greatest distance between them.
• The molecule geometry is determined by the stable arrangement of atoms’ valence electron pairs.
Bonding pairs of electrons (bp) are valence shell electrons that are involved in bonding, while lone pairs of electrons are valence shell electrons that are not involved in bonding (lp).
How to Use VSEPR to Predict Geometry
Step 1: Calculate M by counting the number of valence shell electrons on the centre atom (arbitrary variable)
The core atom in SCl2 is S, which possesses 6 valence electrons. (Shown in step 1 of the Lewis structure drawing)
M=6
Step 2: Determine the number of side atoms and set it to N. (arbitrary variable). There are two side atoms in SCl2 and N=2.
Step 3: Subtract the charge from N for positively charged compounds and add the charge to N for negatively charged compounds if the compound is charged. There is no charge contribution in SCl2, and N=6 is the only value.
Step 4: Add the contributions of the side atoms and charge to the core atom’s contribution, i.e. M+N.
M+N=8 for SCl2.
Step 5: Multiply M+N by 2 to get the total number of electron pairs that affect the form.
There are four electron pairs in SCl2.
Step 6: Separate the total electron pairs into bonding and non-bonding electron pairs. The number of side atoms equals the number of bonding electron pairs.
There are two side atoms in SCl2. As a result, there are two pairs of bonding electrons and two pairs of non-bonding electrons.
The following table can be used to forecast geometry and shape based on this information.
The form of an electron is bent and its geometry is tetrahedral.
Hybridization with SCl2
Many polyatomic compounds have bonding that cannot be explained using atomic orbitals. For instance, ammonia, water, and so forth.
Hybridization is a notion that can be used to describe such substances.
Pure atomic orbitals are mixed to generate equivalent hybrid atomic orbitals. If the pure atomic orbitals have similar forms and energies, mixing is possible.
For example, one 3s and two 3p atomic orbitals can combine to generate three sp2 hybrid orbitals, while 3s and 7d cannot.
This compound’s core atom is S.
S’s electrical ground state configuration is 1s2 2s2 2p6 3s2 3p4. In hybridization, only valence orbitals are utilised.
The promotion of electrons is unnecessary.
These four orbitals (one 3s and three 3p) hybridise to generate four sp3 orbitals, which establish bonds with the atoms around them.
There are two surrounding atoms in SCl2. With one sp3 hybrid orbital, each atom creates a bond.
The lone pair of electrons in the two sp3 hybrid orbitals do not participate in bonding.
With sp3 hybrid orbitals, two Cl atoms create a sigma bond. SCl2 possesses sp3 hybridization as a result.
Another way to figure out what type of hybridization you have is to use a calculator.
In the last step of VSEPR theory, we estimated the total electron pairs. In the case of SCl2, the answer was 4.
We can anticipate hybridization using total electron pairs or steric numbers from the table below.
For the SCl2 compound, the hybridization is sp3.
Polarity of SCl2
The net dipole moment determines a compound’s polarity. The net dipole moment, in turn, is mostly determined by-
• the electronegativities of atoms forming bonds differ.
• the compound’s geometry
Only S-Cl bonds are present in SCl2. S and Cl have electronegativity of 2.58 and 3.16, respectively.
S-Cl bonds are polar because of this difference in electronegativity. From S to Cl, the dipole moment vectors are directed.
Is there a dipole moment in SCl2?
The form of the compound is now the deciding element.
The dipole moment vectors would have balanced each other out if the geometry had been symmetrical, and the compound would have been non-polar.
However, due to the presence of two lone pairs on S, the compound is twisted and asymmetrical.
As a result, the dipole moment vectors do not cancel out, indicating that the combination is polar.
BTW, I’ve written a complete paper about SCl2’s polarity. You must read it out loud at least once. Take a look at SCl2’s polarity.
Conclusion
A covalent molecule is SCl2. At room temperature, it is liquid.
The octet rule and formal charge are satisfied by the Lewis structure in this form. Tetrahedral and bent electron geometry and form, respectively. sp3 is the hybridization.
It’s a polar substance.
Good luck with your studies!
Read more: Molecular Geometry, Polarity, and Hybridization of PBr3 Lewis Structure
