Sulphur dichloride reacts with hydrogen dibromide to form sulphur dibromide. Sulphur dibromide (SBr2) is a toxic gas and not a general chemical compound to use in the field of chemistry.
In this article we are discussing about the SBr2 lewis structure. SBr2 mainly consists of only two elements i.e. sulphur and bromine so it has named as sulphur dibromide. Its diagram, shape, hybridization, Charges on SBr2, its pairing and octet of its elements. The lewis structure of SCl2 and SBr2 is very similar to each other.
How to draw lewis structure for SBr2?
There are two main rules for drawing lewis structure of any molecule or chemical compound.
- First is to count or note the number of valence electrons of each element or atom present in the molecule or chemical compounds or ions. If the ions are there then count the charges on it.
- Complete the octet of every element or atom by putting electron pair after bonding of atoms to each other i.e. every element have eight electrons in its outer orbit, except hydrogen which has only two electrons in its outer shell. Sometimes the molecule forms double or triple bonds. Multiple bonds only form with some elements like oxygen (O), carbon (C), nitrogen (N), phosphorus (P) and sulphur (S) and rarely with Cl.
Chemical formula for sulphur dibromide is SBr2.
Molecular weight of SBr2 is 191.873 g mol-1.
Molecular geometry of SBr2 is Bent shape.
SBr2 has Sp3 hybridization.
SBr2 is slightly polar in nature.
Sulphur dibromide i.e. SBr2 lewis structure consists of mainly two elements sulphur and bromine. There is one sulphur atom and two bromine atoms are present the SBr2 lewis structure. SBr2 lewis structure has four bonding electrons and sixteen non-bonding electrons. It is quite easy to draw the SBr2 lewis structure.
For drawing the SBr2 lewis structure first most is to count the number of valence electrons present in the structure, i.e. count the valence electrons of each element present in the structure. So, count the valence electrons present on sulphur atom and bromine atoms.
For counting the valence electrons of any atom or element check its position in the groups of periodic table. As the element sulphur present on sixteenth group (16th group) of the periodic table and the bromine element present on seventeenth group (17th group) of the periodic table. So sulphur has six and the bromine has seven valence electrons present on it.
Therefore, Total valence electrons for sulphur = 6
Total valence electrons for bromine = 7
So, total valence electrons for SBr2 lewis structure = 6 (S) + 7×2 (Br2) = 20
Secondly choose the least electronegative element of the SBr2 molecule to put in the central position during drawing the lewis structure, as they are more ready to share electrons with the neighbouring surrounding elements or atoms. In this molecule sulphur has 2.58 electronegativity and bromine has 2.96 electronegativity. So the sulphur is less electronegative in nature than bromine. So, sulphur should be in the central position of the structure surrounded by two bromine atoms.
Third point is to connect all the atoms with each other by bonding. So draw single S-Br, S-Br bonds between one sulphur and two bromine atoms to connect them with each other. Means draw two single bonds between right side bromine with central sulphur atom and left side bromine with central atom.
Now count the below SBr2 lewis structure valence, one single bond has two electrons. In SBr2 lewis structure there is the formation of two single bonds. So, from the total twenty valence electrons, four valence electrons get used to draw the SBr2 lewis structure.
Therefore, 20 – 4 = 16 valence electrons
So, there are more sixteen valence electrons have remaining for bonding.
SBr2 lewis structure octet rule
SBr2 lewis structure octet rule tell us about the completion of octet of outer atoms. Valence shell of any atom containing eight electrons is known as octet. SBr2 lewis structure having two bromine element as a outermost atoms and there is a need of eight electrons to complete the octet of bromine atoms in its valence shell. So, all the remaining valence electrons should put on the bromine atom till they have eight electrons to complete the octet.
Now the two bromine atoms in the SBr2 lewis structure completed its octet as they both have eight electrons in its valence shell. [Dots represented six electrons on bromine atoms and two electrons as a single bond with sulphur]
Then count the total valence electrons in the SBr2 lewis structure used till now. In SBr2 lewis structure twelve electrons represented as dots on two bromine atoms and two single bonds S-Br with sulphur i.e. four electrons used.
Therefore, 12 + 4 = 16 total valence electrons used in SBr2 lewis structure from total twenty valence electrons. Now, 20 – 16 = 04 so, four more valence electrons gets remain.
Now, octet of both outer bromine atoms gets completed, then complete the octet of sulphur atom situated centrally in the SBr2 lewis structure. The central sulphur atom has two single bonds i.e. sulphur atom has already four electrons in its valence shell, so only four extra electrons needed by sulphur to complete its octet.
Also already there are four valence electrons are remaining from total twenty electrons, so place all the four remaining valence electrons around central sulphur atom to complete its octet.
So, this way all the remaining available valence electrons were used to draw the SBr2 lewis structure and all SBr2 elements i.e. sulphur and bromine have eight electrons in its valence shell means having complete octet.
SBr2 lewis structure formal charges
The stability on any lewis diagram is more when atoms have less formal charges. There is a formula to calculate formal charge on any atom in lewis diagram.
Formal charge = (valence electrons – lone pair of electrons – ½ bonding electrons)
First we should count the formal charge on both bromine atoms of SBr2 lewis structure. There are equal lone pair electrons and bonded pair electrons on two bromine atoms of the structure so let us just we can count the formal charge of only one bromine atom.
Bromine atom: Valence electrons for Br = 07
Lone pair electrons for Br = 06
Bonding electrons with Br = 2 (one single bond)
Formal charge of Br = (7 – 6 – 2/2) = 0
So, both bromine atoms have zero formal charges.
Sulphur atom: Valence electron for central S atom = 6
Lone pair electrons on central S atom = 4
Bonding electrons around central S atom = 4 (two single bonds)
Formal charge of S = (6 – 4 – 4/2) = 0
So, the central sulphur atom in SBr2 lewis structure has zero formal charge.
SBr2 lewis structure lone pairs
As shown in the following SBr2 lewis structure, we can see there are six lone pair of electrons on each of the outer bromine atoms of SBr2 lewis structure, so there are total twelve lone pair of electrons on both the outer bromine atoms.
Similarly the central sulphur atom of SBr2 lewis structure has four lone pair of electrons in its valence shell. So, SBr2 lewis structure has 6 + 4 + 6 = 16 lone pair of electrons. Therefore, the total number of lone pair of electrons in SBr2 lewis structure is sixteen.
SBr2 lewis structure shape
The SBr2 lewis structure has bent shape as per its molecular geometry. The bent shape is due to the central sulphur atom gets attached with two bond pairs and also has two lone pair of electrons on sulphur atom. So, VSEPR theory says there is repulsion between the bond pair electrons and lone pair of electrons surrounded by sulphur atom, due to which they get pushed away from each other and pushes down the bonded atoms giving SBr2 lewis structure a bent shape. VSEPR theory gives AX2N2 generic formula for SBr2.
As the central sulphur atom of SBr2 lewis structure has two bond pairs of electron and two lone pair of electrons means having four sections of density of electrons, so it has bent molecular geometry and tetrahedral electron geometry.
SBr2 lewis structures hybridization is found by its central atoms steric number.
Sum of total number of bonded atoms attached with central atom and lone pair of electrons present on it is known as steric number.
Steric number of SBr2 = (no. of bonded elements or atoms attached with sulphur + lone pair of electrons on sulphur)
According to the SBr2 lewis structure, Sulphur has two lone electron pairs and it is attached with two bromine atoms.
So, SBr2 steric number = 2 + 2 = 4
As the calculated steric number of SBr2 lewis structure is four, so it has Sp3 hybridization of sulphur in SBr2 structure.
SBr2 lewis structure has less than 109.5 degree angle. The central sulphur atom has two lone pair of electrons due to which the two bromine atoms slightly comes close with each other, which makes the bond angle less than 109.5 degree.
SBr2 lewis structure resonance
In resonance structure electrons distribution vary from one structure to another structure. As we see the rules to draw the resonance structure of any lewis structure, there is a need of multiple bonds in the structure and the neighbouring atom has at least one lone pair of electron. If these conditions get fulfil in any structure we can draw its resonance structure by distributing the electrons and charges of atoms in that structure.
If we talk about the SBr2 molecule resonance structure, the resonance structure of SBr2 molecule is not possible because it does not have any formal charge on it and also it does not have any multiple bonds (double or triple bonds) in the SBr2 lewis structure.
SBr2 molecule has zero formal charge and the central sulphur atom attached with two bromine atoms with single covalent bond and even the octet of two outer bromine atoms and central sulphur atoms are completed. So SBr2 molecule can consider a stable molecule which does not form any resonance hybrid structure of it.
Polarity of SBr2 lewis structure
SBr2 lewis structure has bent geometrical shape due to which it is non-polar or very slightly polar in nature. Due to the bent shape of SBr2 molecule it has some net dipole moment; even the S-Br bond is non-polar because it has very less electronegativity difference between sulphur and bromine atoms. So, SBr2 is non-polar or very slightly polar we can say.
Bromine has electronegativity 2.96 and sulphur has electronegativity 2.58. So sulphur and bromine has the electronegativity difference of 0.38. As per the Pauling’s scale, S-Br bond has very less electronegativity difference which is less than 0.5, so it is non-polar in nature.
As the bromine atom is quite more electronegative in nature than sulphur atom, can cause quite a small negative charge on bromine atom and small positive charge on sulphur atom. Due to this charge separation, the dipole arises within the bond and it is not able to cancel out because of the SBr2 V-shaped structure. But this dipole moment is so small due to very less electronegative difference of Br and S. As a result of this SBr2 molecule is non-polar or slightly polar in nature.