SnO2 Lewis structure: Drawings, Hybridization, Shape, Charges, Pair And Detailed Facts

In this article named “sno2 lewis structure” lewis structure, formal charge calculation, shapes, hybridization with some relevant topics on Tin dioxide (SnO₂) are explained thoroughly.

Stannic dioxide or SnO₂ is a very important material in chemistry having molecular weight 150.71 g/mol. It is yellowish or light green crystalline compound with a linear structure. The hybridization of Sn is sp with two double bonds with the two oxygen atoms.

Let’s have a look on the following discussions on Tin dioxide.

How to draw lewis structure for SnO₂?

Lewis structure is none other than a structural representation of any molecule introduced by Gilbert. N. Lewis in 1916 in which nonbonding electrons are shown as the electron dots around the respective atoms.

The steps of drawing a lewis structure of SnO2 are-

1. Finding out the valance electron: In this structural representation valance electrons have a significant role. So, to draw the lewis structure of SnO2, it is important to determine the valance electron of each of the atoms. Tin (Sn) has four and oxygen has six electrons in their respective outer most shell.
2. Determination of bonds and bonding electrons: Total four covalent bonds (two double bonds) are present in tin dioxide (SnO₂) molecule between Sn and two oxygen atoms. Due to having four bonds, total 4×2 =8 electrons are involved to form the four bonds.
3. Finding out the nonbonding electrons: The electrons do not participate in bonding are called nonbonding electrons. Though Sn has no electrons are left as nonbonding but each of the oxygen atom has four nonbonding electrons.

SnO₂ Lewis Structure Shape

Molecular shape is determined by the hybridization of its central atom. If the hybridization changes, molecular shape will also be changed. The changes of structure with the changes of hybridization are shown in the following chart.

Hybridization of central atom	Structure
sp	Linear
sp2	Trigonal planar
sp3	Tetrahedral
sp3d	Trigonal bipyramidal
sp3d2	Octahedral

But if central atom has lone pair (s) then the actual geometrical structure (predicted from hybridization) is violated due to some repulsion. These repulsions are-

• Lone pair- lone pair repulsion
• Lone pair-bond pair repulsion
• Bond pair-bond pair repulsion

The increasing order of the above repulsion is-

Lone pair -lone pair repulsion > Lone pair – bond pair repulsion > Bond pair- bond pair repulsion.

In SnO₂, Sn is sp hybridized. So, according to the above chart the geometrical structure of SnO₂ should be linear. The actual shape of SnO₂ is also linear because central atom Sn has no nonbonding electrons or lone pair. Thus, no bond pair lone pair or lone pair lone pair repulsion is present to deviate the actual shape from its geometrical structure.

SnO₂ Lewis Structure Formal Charges

Formal charge calculation is nothing but the way out to determine the most stable lewis structure. There is a formula in inorganic chemistry to calculate the formal charge of each of the atom present in the molecule.

• Formal charge = Total number of valance electrons – number of electrons remain as nonbonded – (number of electrons involved in bond formation/2)
• Formal charge of the Tin (Sn) = 4 – 0 – (8/2) = 0
• Formal charge of each of the oxygen atom = 6 – 4 – (4/2) = 0

From the calculation of formal charge we can easily say that every atom of this molecule is neutral and as well as the whole molecule is also neutral in nature.

SnO₂ Lewis Structure Lone Pairs

Lone pairs or nonbonding electrons are basically one type of valance electrons who do not participate in bonding and shown as electron dot in the lewis structure around the respective atoms.

• Nonbonded electron = Total number of valance electron – number of bonded electrons.
• Nonbonding electrons on Sn = 4 – 4 = 0
• Nonbonding electrons on each of the oxygen atom = 6 – 2 = 4 or 2 lone pairs.

All the four valance electrons of Sn are involved in bonding. Thus, it has no electrons left as nonbonding. But only two electrons of oxygen participate in two covalent bond formation. So, (6-2 = 4) electrons remain as nonbonding.

Thus, total nonbonding electrons in SnO₂ = [0 + (4×2)] = 8 or 4 lone pairs.

SnO₂ Hybridization

The word “hybridization” is introduced in chemistry to say about the mixing of atomic orbitals. As a result of mixing the two orbitals having similar energies, shapes and symmetry, a new hybrid orbital is generated. This process is called hybridization. Total five basic types of hybridization are observed in most of the molecule.

The hybridization and the corresponding shapes are described below-

1. Planar (sp)
2. Trigonal Planar (sp²)
3. Tetrahedral (sp³)
4. Trigonal bipyramidal (sp³d²)
5. Octahedral (sp³d²)

In SnO₂, the central atom Sn is sp hybridized. But in this hybridization one s and three p orbitals are participating to form the four covalent bonds (two sigma and two pi bonds). As hybridization depends only on the sigma bonds, so Sn shows sp hybridization in SnO₂.

This sp hybridization directs the molecule to be linear shaped (shown in above chart).

SnO₂ Lewis Structure Octet Rule

Octet rule is one of the significant rule in chemistry which states that any atom should achieve the electron configuration in their respective valance shell like its nearest noble gas.

In this molecule SnO₂, all the participating atoms obey octet rule. Sn has already four valance electrons (5s² 5p²). These four electrons are involved in the four covalent bonding with the two oxygen atoms. So, Sn achieves eight electrons in its valance shell and matches with the valance shell electron configuration Xenon or Xe (5s² 5p⁶).

Octet rule is also satisfied for each of the two oxygen atoms. It has six electrons in its outer most shell and it forms two bonds with the Sn. Thus, total number of electrons in its valance shell is eight which resembles with its nearest noble gas in periodic table Neon or Ne (2s² 2p⁶).

SnO₂ Polar or Nonpolar

Polarity of any molecule depends upon these two following factors-

1.  Polarity of the bonds present in the molecule
2. Orientation of the substituent groups or atoms with respect to each other.

Sn-O bonds are polar because of the electronegativity difference between S and and Oxygen (the electronegativity of tin and oxygen is 1.96 and 3.44 in Pauling scale respectively). But due to linear shape, SnO₂ is non polar because both the Sn-O bonds are aligned with each other in the angle 180⁰. Thus, one bond moment is cancelled by the another bond moment. For this alignment of these two bonds SnO₂ shows zero dipole moment.

Uses of SnO₂

Tin dioxide has different uses in industry like-

• It is a very good semiconductor and SnO₂ nanoparticle are widely used as photocatalyst in dye degradation of organic compounds.
• It is also used to detect of different gases as it is a very good gas sensing element.

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