SiS₂ (Silicon disulfide) exhibits a linear Lewis structure: a central silicon (Si) atom with 4 valence electrons forms double bonds with two sulfur (S) atoms, each with 6 valence electrons. Total of 16 valence electrons are utilized. No lone pairs on Si, resulting in a 180° bond angle. Electronegativity values: Si (1.90), S (2.58), suggesting polar bonds due to the difference. The molecule is nonpolar overall due to its linear, symmetrical structure, balancing the electron distribution.
Drawing of SIS2 Lewis structure
The step by step drawing process of Lewis structure of the compound Silicon disulphide would be relevant to describe the molecular formation of the compound. It follows the common steps of drawing a Lewis structure.
The total number of valance electrons that participate in the formation of SIS2 is needed to be calculated first. The number of valance electron in one Silicon atom is four and each of the two-sulphide atoms has 6 valance electrons. Therefore the total number of valance electrons in SIS2 is (4 + (2*6)) = 20.
Silicon shares two electrons to each of the Sulphur atoms. Two sulphur atoms share their one electrons from last electronic shell. This electron sharing process is considered as the next step of the drawings Lewis structure.
Silicon makes two double bonds with two sulphur atoms. The bonds are covalent as this are made by electron sharing. Though Silicon is less electronegative tan Sulphur atoms, only one Silicon participates in the formation of this compound.
Shape of SIS2 Lewis structure
The compound holds normal linear shape. It is important to notice the shape to identify the geometry of the compound.
The shape of SIS2 is triatomic linear as three atoms participate in the formation of their crystalline structure. The crystalline shape of design of the compound is Orthorhombic. Besides, the geometric structure is defined as tetrahedral.
Formal charges in SIS2 Lewis structure
In the case of finding the formal charges that’s are possessed by each of the atoms participated in the formation of a compound a formula must be followed to calculate the number correctly.
The formula of finding the formal charges of atoms is (valence electrons – nonbonding electrons – ½ bonding electrons).
Therefore, the formal charge of Silicon in SIS2 is (4-0-1/2*(4)) = +2, where the number of nonbonding electrons in Silicon is 0 and bonding electron is 4.
Formal charge of each of the Sulphur atom is (6-6-1/2*(2)) = -1, where each of the sulphur atom has 6 nonbonding elections and 2 bonding electrons.
Lone pairs in SIS2 Lewis structure
Lone pairs in this compound are found to be converted into bonds. All the six lone pairs of Silicon take place in electron sharing process. There are three lone pairs remain in each of the sulphur atom after participating in bonding with the central Silicon atom.
The one lone pair of sulphur converts into a bond that is Si-S. Again lone pair of other sulphur atom converts itself into a silicon-sulphur bond that is Si-S.
SIS2 Hybridization
The Lewis structure of the Silicon disulphide (SIS2) says that the compound holds sp hybridization. Hybridization refer to newly formed orbital structure which takes place after the formation of combination between two different orbitals of two different elements.
Sp hybridization takes place in the tetrahedral shape of Silicon disulphide. In linear triatomic compound the orbitals of the central atom that is silicon overlaps with the p orbital of the sulphur atom in presence of lone pairs.
Resonance in SIS2 Lewis structure
Resonance indicates the process of alternating the bond structure without differing the formula of the main compound. The structural change is influenced by the concept of resonance.
SIS2 holds two double binds where the total 8 electrons take part in formation of the bonding. Both the double bonds are similar and when they take place in resonating structure the bonds structure remains same and it make the compound neutral without exposing any different resonance structure.
The compound is purely inorganic and the electron sharing process takes place for both the sulphur atom with the centralised Silicon in a similar way. It makes the neutral structure, which does not need to show different resonating structure and it sustains similar formal charges.
Octet rule of SIS2 Lewis structure
Fulfilling the octet rule is the main motive for each of the atoms in Silicon disulphide. Not only this compound all the periodic elements undergo combination for the adoption of octet state and high stability as their nearest noble gas.
Silicon disulphide is made of Silicon and Sulphur atoms. Silicon needs four electrons in its last electronic shell to get filled orbital like its nearest noble gas, Neon. Sulphur atoms need two electrons to get electronic configuration like Argon.
After adopting four electrons through electron sharing processes with the sulphur atoms, Silicon got filled octet and adopting the two electrons from Silicon the each of the sulphur atoms filled their octet state. In this way the compound SIS2 got filled octet rule.
Finding if SIS2 polar or nonpolar
Polarity and non-polarity depend on the bonding and tension among the bonds. However, the presence of lone pairs also impacts on the polar or non-polar nature of a compound.
In SIS2, the bonds are polar but the equal intensity of the bonds cancels pout the polarity of the overall compound. The molecules show anomaly nature, which refers to the non-polar characteristic of the compound. Therefore, Silicon disulphide is basically non-polar compound in nature.
On the other hand, sulphur molecules have lone pairs that effect on the S-Si bonds. This makes the compound a bit polar by nature with a contradictory.
Frequently Asked Questions (FAQs)
Questions 1: Is SIS2 considered as a polymer?
Answer: The inorganic structure of SIS2 can be considered as a polymeric structure as well. From the Lewis structure of the of the compound many properties are found to be similar with polymeric characteristics in SIS2.
Questions 2: What is the bond angle in SIS2?
Answer: The bond angle in Silicon disulphide is 180°. It takes place due to the shift of the shape of SiS2 from bent shape to linear.
Questions 3: Which is responsible for promoting sp hybridization to Silicon disulphide?
Answer: The linear trigonal shape of tetrahedral geometry is the main reason, which promotes it sp hybridised structure.
Questions 4: How many lone pairs are present in SIS2? How do they affect the polarity of the compound?
Answer: The central atom that is Silicon does not hold any lone pairs after creating bonds with the sulphur atoms but each of the sulphur atoms have two lone pairs.
The presence of lone pairs influences the polarity of the compound by creating tension upon the S-Si bonds.
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Hi…..I am Sarnali Mukherjee, a graduate from the University of Calcutta. I love to teach and share knowledge on chemistry. I have gradually gained interest in article writing since one year ago. I would love to acquire more knowledge on my subject in the future.
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