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SF6 Lewis Structure, Molecular Geometry, Shapes and Polarity

This article is about the SF6 Lewis Structure, the Molecular geometry, and the formal charge present in the molecule.


What is Lewis’s structure and why it is important to study Lewis’s structure?

A Lewis Structure is a graphical representation of the valence shell electrons of a molecule. It’s used to illustrate how electrons in a molecule are distributed around specific atoms.

Electrons are depicted as “dots” or as a line between two atoms when they are bonded. The main goal of the Lewis Structure is to find the “optimal” electron configuration, which requires that the octet rule and formal charges be maintained.

The Lewis structure was initially proposed by famous scientist Gilbert N. Lewis in his journal “The Atom and the Molecule” in 1916. The Lewis structure is important in chemistry because it can predict the number of bonds, nonbonding electrons, and bonding electron structure.

Lewis structure does not try to explain the molecular shape, bond formation, or electron sharing between atoms. It is the most basic and limiting explanation of the electrical structure.


What is Sulfur Hexafluoride (SF6)?


what-is-sulfur-hexaflouride

One Sulphur atom and six fluorine atoms make up the chemical Sulfur Hexafluoride (SF6). It’s a colorless, non-flammable inorganic greenhouse gas with an octahedral shape containing one Sulphur atom and six fluorine atoms.

It is hypervalent and has an orthorhombic crystalline structure.

The length of the S-F single bond.156.4 pm is

Valence Electrons

Valence electrons are the electrons that make up an atom’s outermost shell or top energy level. To study the Lewis Structure of any molecule, it is very important to understand the electrons present in the valence shell.

SF6 Lewis Structure

In the SF6 Lewis Structure, six single bonds surround the Sulphur atom, which has six fluorine atoms linked to it and three lone pairs on each fluorine atom while there is no lone pair on the Sulphur atom.

Any molecule’s Lewis Dot structure is a graphical representation of the atoms that make up the structure and their respective valence electrons. This structure enables us to understand the molecule’s bond forms and electron arrangement.

Because Sulphur is less electronegative than Fluorine, it will assume the middle position. As a result, arrange it in the middle and all Fluorine atoms around it.

In the SF6 Lewis Structure, there are six sigma bonds present between Sulphur and six fluorine atoms. Each fluorine atom has three lone pairs. Because there are 6 sigma bonds surrounding the Sulphur atom, the valence shell of Sulphur has 12 electrons. Sulfur can retain more than 8 electrons in its final shell. There are no charges on the atoms in the SF6 Lewis structure, and the molecule has no overall charge.

Steps to Remember While Drawing SF6 Lewis Structure

To draw a Lewis structure of a molecule, there are a few general steps to follow. The number of steps can be adjusted depending on the molecule or ion’s complexity. We’ll look at each stage of drawing the Lewis structure of Sulfur Hexafluoride (SF6).

· Calculate the total number of electrons in the valence shells of the Sulphur and fluorine atoms.

· Total electron pairs exist as lone pairs and bonds.

· Choosing the center atom

· Draw lone pairs.

· Mark charges on atoms

· To acquire the optimum Lewis structure, check the stability and decrease charges on atoms by converting lone pairs to bonds.


1. Calculate the total number of electrons in the valence shells of the Sulphur and fluorine atoms


To draw the SF6 Lewis Structure, first, we have to Calculate the valence electrons present in the Sulfur Hexafluoride (SF6) molecule. Sulfur hexafluoride is made up of only two elements:


Sulphur and fluorine


Sulfur is a VIA element in the periodic table group with six electrons in its final shell (valence shell). With seven electrons in its outermost shell, fluorine is an element in group VIIA of the periodic table.

Valence electrons of sulfur = 6 * 1 = 6

Valence electrons of Fluorine atoms = 7 * 6 = 42

Total valence electrons in SF6= 6 + 42 = 48


2. Total Electron Pairs Exist as Lone Pairs and Bonds


in the second step of drawing the SF6 Lewis Structure calculate the total valence electron pairs. Total valence pairs of electrons mean the total number of a sigma bond and the pi bond present in a molecule. To get the total number of electron pairs, divide the total number of valence electrons by two. In the valence shells of Sulfur Hexafluoride (SF6), the total pairs of electrons in SF6 are 24.

Hence, 48/2= 24

3. Choosing the Center Atom

Being the core atom of a molecule has its own set of criteria. The most significant aspects of being the center atom are having a high valence and being the most electropositive atom. In SF6, there are only two conditions for selecting the center atom, and we’ll go through those requirements as well as the molecule’s basic drawing.

Maximum valence: The maximum valence of Sulphur is 6. The highest valence of fluorine is 1. As a result, Sulfur has a high priority for being the central atom.

It is clear from the above fact that Sulfur should be the central atom for the Lewis structure of Sulfur Hexafluoride (SF6).

4. Draw Lone Pairs on Atoms

The next step in SF6 Lewis Structure, after choosing the central atom is to draw lone pairs on the atoms of a molecule. To draw lone pairs, it is important to remember how many total numbers of electron pairs are present. so, in the case of Sulfur Hexafluoride (SF6), there are 24 electron pairs present to make bonds and lone pairs on SF6.

From the figure above it can be seen that there are six sigma bonds present while 18 lone pairs can be marked on Sulphur and fluorine atoms.

Usually, the remaining electron pairs should be used to make marks on external atoms (in this case on fluorine atoms). Then, on fluorine atoms, draw lone pairs. As three lone pairs will be required for each fluorine atom. Therefore, a total of 18 electron pairs are now present as lone pairs around the fluorine atom. While there is no lone pair on Sulphur as all electrons are shared with fluorine.

5. Mark and Stabilize Charges on Atoms

Because there is no charge on atoms in Sulfur Hexafluoride (SF6), therefore there is no need to reduce or stabilize the charges. That means we can say that the Lewis structure of SF6 is already done.

Importance of Lewis Structure

Lewis structure of any molecule is important because

· It allows us to predict how many bonds it will form. This understanding will eventually allow us to identify molecule forms and chemical characteristics.

Importance of SF6 Lewis structure

· The SF6 Lewis structure of helps us understand the molecule’s shape, bonding, and properties.

· SF6 Lewis Structure shows how atoms are bonded to each other and represent the arrangement of electrons in a molecule.

· SF6 Lewis Structure has six fluorine atoms bonded to a central sulfur atom, as shown by its Lewis structure.

· The sulfur atom in SF6 Lewis Structure has six valence electrons, while each fluorine atom has seven valence electrons.

· The SF6 Lewis Structure can be used to predict its reactivity, polarity, and other properties.

Molecular Geometry of Sulfur Hexafluoride (SF6)



Molecular Geometry of Sulfur Hexafluoride (SF6)



Because the structure of Sulphur hexafluoride comprises a central Sulphur atom around which 12 electrons or 6 electron pairs are present and no lone pairs, therefore molecular geometry of SF6 will be octahedral. There will be a 90-degree angle between the F-S-F bonds.

The Geometry of SF6 Molecule by AXN notion

The basic geometry of the molecule or ion will be described using the AXN notation, where A represents the core atom which is Sulphur in this case and X represents the terminal atoms that are singly bound to the central atom which is fluorine. The letter “n” denotes the number of lone pairs, which in the case of SF6 is zero.

The Shape of Sulfur Hexafluoride (SF6)

We can say that the SF6 molecule has an octahedral form because it has eight sides when looking at its chemical geometry. The center atom, on the other hand, binds with six Fluorine atoms, giving SF6 its octahedral structure.


Sulfur Hexafluoride (SF6) Bond Angle

We can see that all six electrons of the Sulphur atom are shared to form bonds because it shares its valence electrons with 6 Fluorine atoms. F-S-F has a 90-degree bond angle.



SF6-Lewis-Structure
SF6 Lewis Structure



Molecular Orbital Theory

This theory is concerned with electron repulsion and the need for compounds to take on a form to achieve stability. There are six sigma bonds between Sulfur and Fluorine in SF6, as well as three lone pairs on each Fluorine atom. These single electrons compete with one another to maintain the symmetry of the central atom.

Even though sulfur only has four valence orbitals, the Lewis structure of sulfur hexafluoride specifies six pairs of electrons as bond pairs. As a result, d-orbitals must be used to describe the valence bond of this hypervalent complex. However, high-level theoretical calculations indicate that the electronic structure consists of only four bonds, each delocalized over all seven atoms, rather than d-orbitals and six bonds.


SF6-Lewis -Structure
SF6 Lewis Structure

Hybridization of SF6

The orbitals involved and the bonds produced during the interaction of Sulfur and fluorine molecules will be examined to determine the hybridization of Sulfur hexafluoride. 3s, 3py, 3py, 3pz, 3dx2–y2, and 3dz2 are the orbitals involved. The Sulfur atom, which is the central atom in its ground state, will have the 3s23p4 configuration in its formation.

The electron pairs in the 3s and 3px orbitals become unpaired in the excited state, and one of each pair is promoted to the unoccupied 3dz2 and 3dx2-y2 orbitals. All six half-filled orbitals (one 3s, three 3p, and two 3d) hybridize now, resulting in the production of six sp3d2 hybrid orbitals.



SF6-Lewis-Structure
SF6 Lewis Structure


The Polarity of Compounds

SF6-Lewis-Structure
SF6 Lewis Structure

Polarity of SF6

When we examine a compound’s structure and properties in-depth, the polarity of the compound is a significant topic of discussion.

The charge distribution is uniform across the SF6 molecule, resulting in a dipole moment of 0. The dipole moment is canceled due to the symmetric configuration. As a result, sulfur hexafluoride is non-polar.

Factors affecting polarity

· Electronegativity

The stronger the atom’s ability to attract bound electrons, the higher its electronegativity. As a result, the difference between the electronegativity of atoms is precisely proportional to the polarity of a molecule.

· Dipole Moment


SF6 Lewis Structure


The dipole moment is a measurement used to find out the level of polarity. A molecule’s polarity increases as its dipole moment increases.

A molecule’s polarity and dipole moment are proportional

· Geometrical Shape

A molecule’s geometrical shape has a significant role in defining its polarity. A molecule’s dipole moment is 0 for symmetrical molecules. A nonpolar molecule is formed when a molecule has a polar bond because the dipole moments of the molecules cancel each other out.

Characteristics of SF6

​The chemical formula of sulfur hexafluoride

SF6

Boiling point

-63.9°C (1atm, sublimation)

Melting point

-50.8°C (224kPa)

Sublimation

-63.9°C (1atm)

Density (gas)

6.04kg/m3 (25°C, 1atm)

Density (liquid)

1,339kg/m3 (25°C)

Molecular mass water solubility in SF6

0.01%

Solubility in Water

0.0063mLSF6/mL water



Chemical Characteristics of SF6

· SF6 is colorless and odorless and extremely combustible.

· It weighs five times more than air.

· Sulfur hexafluoride is chemically inert

· It has excellent Dielectric characteristics.

Applications of SF6

About 80% of the Sulphur hexafluoride is used in the electrical power industry, largely as a gaseous dielectric medium. It is also used as a silicon etchant in semiconductor fabrication and as an inert gas in magnesium casting.

Dielectric Medium

· SF6 is a gaseous dielectric medium used in the electrical industry to replace oil-filled circuit breakers (OCBs) that can contain dangerous polychlorinated biphenyls in high-voltage Sulphur hexafluoride circuit breakers, switchgear, and other electrical equipment (PCBs).

· SF6 is also used as a high voltage dielectric in particle accelerators having high voltage supplies, such as Van de Graaff generators and Pelletrons, as well as high voltage transmission electron microscopes.

Medical Use

· In retinal detachment repair surgeries, SF6 is utilized to produce a tamponade or plug of a retinal hole in the form of a gas bubble.

· In retinal detachment repair surgeries, SF6 is used to produce a tamponade or plug of a retinal hole in the form of a gas bubble.

· For ultrasound imaging, SF6 is used as a contrast agent.

· A peripheral vein receives an injection of Sulphur hexafluoride microbubbles in solution form. For ultrasonography, these microbubbles increase the visibility of blood vessels.

SF6 as a Tracer Compound

Gaseous SF6 is used for Short-term trials of ventilation efficiency in buildings and indoor enclosures, as well as in assessing infiltration rates.

Two primary factors recommend its usage:

· its concentration can be detected with reasonable accuracy at extremely low quantities.

· the concentration of SF6 in the Earth’s atmosphere is insignificant.

In an experiment at London’s St John’s Wood tube station, Sulphur hexafluoride was employed as a non-toxic test gas.

Some Other Uses of SF6

· To prevent oxidation during casting, the magnesium industry uses SF6 as an inert “cover gas.”

· It has been utilized as a filler in insulated glazing windows to improve their thermal and acoustic insulation properties.

· In the semiconductor sector, SF6 plasma is applied as an etchant in techniques like deep reactive-ion etching.

· In the plasma, a little amount of SF6 is broken down into Sulphur and fluorine, with the fluorine ions reacting chemically with silicon.

· Due to the greater molecular size, it takes longer for tires loaded with it to deflate due to diffusion through the rubber.


Conclusion

Now that we’ve reached the end of this lesson, let’s review what we’ve learned so far about the SF6 chemical in this article. In this article, we have discussed the Lewis structure of SF6 which is a colorless, odorless gas that is non-flammable and non-combustible. For the Lewis structure, Sulfur is the core element, which is connected to six fluorine atoms.

On fluorine, the Lewis dot structure has 6 sigma bonds and rests in lone pairs. Then we discussed the points to remember while drawing Lewis’s structure and why it is important to study the Lewis structure. The molecular geometry of SF6 and shape is octahedral and the bond angle is 90 degrees.

Hybridization of the molecule has been discussed which is sp3d2 type. Sulfur Hexafluoride is a nonpolar molecule and different factors can affect the polarity of the molecule which include electronegativity, dipole moment, and the molecular geometry of the molecule.

SF6 has different physical and chemical characteristics which have been discussed in that article. Uses of sulfur hexafluoride include as a dielectric medium, for medical purposes.


FAQs

What is Lewis’s structure?

A Lewis Structure is a simplified representation of a molecule’s valence shell electrons. It’s used to illustrate how electrons in a molecule are distributed around specific atoms. When two atoms are bound together, electrons are shown as “dots” or as a line. The main goal of Lewis Structure is to find the “optimal” electron configuration, which requires that the octet rule and formal charges be maintained

Why it is important to study Lewis’s structure?

Ans: The Lewis structure is important in chemistry because it can predict the number of bonds, nonbonding electrons, and bonding electron structure. Lewis structure does not try to explain the molecular shape, bond formation, or electron sharing between atoms. It is the most basic and limiting explanation of the electrical structure.

SF6 is polar or non-polar?

The charge distribution is uniform across the Sulfur Hexafluoride(SF6) molecule, resulting in a dipole moment of 0. The dipole moment is cancelled due to the symmetric configuration. As a result, SF6 is non-polar.

What is the molecular geometry of SF6?

Because the structure of Sulfur hexafluoride comprises a central Sulfur atom around which 12 electrons or 6 electron pairs are present and no lone pairs, therefore molecular geometry of SF6 will be octahedral. There will be a 90-degree angle between the F-S-F bonds.





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