Is SF6 a polar or nonpolar substance?

Sulfur Hexafluoride is a chemical compound with the formula Sulfur Hexafluoride. The inorganic compound SF6 has a colourless appearance. It is a colourless, odourless, non-toxic, and flammable gas. It is classified as a highly potent greenhouse gas. Many pupils may be unsure whether or not SF6 is polar. In this post, I will respond to this question as well as discuss related themes.

Is SF6 Nonpolar or Polar? In nature, SF6 is a nonpolar compound because, according to VSEPR theory, six fluorine atoms are placed symmetrically with the sulphur atom, cancelling out the dipole moment of the S-F bond, making it a nonpolar combination.

Sulfur hexafluoride is the IUPAC name for SF6, and it is considered an extreme gas that contributes to the greenhouse effect.

It’s a colourless gas that’s non-toxic. In addition, it is not combustible in nature.

When it comes to conductivity, SF6 is a great insulator. It is not an electrical conductor.

One sulphur atom and six fluorine atoms make up a molecule of sulphur hexafluoride. The core element is sulphur, which is linked to the six fluorine atoms.

Two fluorine atoms create covalent bonds axial to the molecule, while four fluorine atoms are covalently bound in one plane to form a square.

As a result, the shape of the SF6 molecule is octahedral in shape. The shape of this geometrical building is symmetrical.

In its outermost shell, the sulphur atom possesses 6 valence electrons, while fluorine has 7.

The covalent bonds between the S and F atoms stabilise each other, resulting in a stable SF6 molecule with a symmetrical geometrical structure.

Fluorine has an electronegativity of 3.98, while sulphur has an electronegativity of 2.58. As a result, there is a difference in electronegativity between the two atoms.

Because of this disparity, both atoms share bound electrons unequally.

The ability of an atom to draw a bound pair of electrons towards it is known as electronegativity.

As a result, the more electronegative atom attracts the bound electron pair closer to itself.

Similarly, the fluorine atom draws the linked pair of electrons towards itself, gaining a partial negative charge in the process. The sulphur atom acquires a partial positive charge in exchange.

The dipole moment in the S-F bond is generated due to polarity in the bond.

What Is the Difference Between Polar and Nonpolar Molecules?

Atoms in molecules are held together by a variety of forces, including ionic, covalent, metallic, and hydrogen bonds.

Ionic and covalent bonds are regarded as the most powerful of all the bonds. Chemical compounds frequently use these two bonds.

Ionic bonds are created when the atoms in a molecule are charged in opposite directions. The ionic forces attract the oppositely charged atoms to each other. Electrolytic chemicals such as NaCl and KCl are only a couple of examples.

Covalent compounds are those in which the atoms share electrons in order to stabilise themselves.

The electronegativity of the atoms determines whether the covalent bonds are polar or nonpolar.

Nonpolar molecules are those in which the bound electron pair is shared equally between both atoms. It signifies that the charge distribution on both covalently bound atoms is equivalent.

Because these atoms have no variations in electronegativity, they share a bigger part of the bound electron pair.

Such atoms have a symmetrical geometrical shape.

Polar Molecules: These are molecules in which the fraction of bound electron pairs between the two atoms is uneven. The charge distribution on both atoms is uneven.

The electronegativity ratings of these atoms are different. Because it attracts the bound electrons farther towards itself, the more electronegative it is, the more partial negative charge it obtains.

What makes SF6 a nonpolar substance?

Six fluorine atoms and one sulphur atom make up sulphur hexafluoride. Because fluorine has a higher electronegativity than sulphur, the S-F bond becomes polar.

As a result, the S-F bond has a non-zero dipole moment.

A chemical compound’s polarity is measured by its dipole moment. The polarity of a compound is proportional to its dipole moment.

It is vital to note that if a molecule contains polar links and the shape of the molecule is symmetrical, the dipoles cancel each other out due to the symmetry of the molecule.

In the same way, the six dipoles of the S-F bonds in the SF6 molecule cancel each other out, resulting in a nonpolar SF6 molecule.

Despite the presence of polar connections inside the SF6 molecule, the entire molecule is nonpolar.

Factors that influence the polarity of a chemical

Electronegativity: The stronger an atom’s ability to attract bound electrons, the higher its electronegativity.

As a result, a molecule’s polarity is proportional to the difference in electronegativity between atoms.

The dipole moment is a metric for determining a chemical compound’s polarity level. A molecule’s polarity is proportional to its dipole moment.

The dipole moment is exactly proportional to a molecule’s polarity.

The magnitude and direction of the dipole moment are both vector quantities.

Geometrical shape: A molecule’s geometrical shape plays a significant role in defining its polarity. The molecules that have a symmetrical form have a dipole moment of zero.

If a molecule contains a polar bond, the dipole moment of the molecules cancels out, resulting in a nonpolar molecule.

The SF6 Geometrical Structure

There are six covalent bonds between S and F in the geometrical geometry of sulphur hexafluoride. Four of them are in the same plane, forming a square planar, and two of them are axial to it.

As a result, the molecule takes on an octahedral shape. The F-S-F are all perpendicular to one another.

The six covalent connections created involve all six valence electrons, leaving no lone pair behind.

The geometrical structure of SF6 is depicted in the diagram below.

Sulfur hexafluoride has an atomic number of 16 and an electronic configuration of 2, 8, 6, i.e. 1S2 2S2 2P6 3S2 3P4

This substance is colourless and extremely combustible.

At a temperature of 20 degrees Celsius, the density of sulphur hexafluoride gas is 6.14 kg/m3.

This gas has a thermal conductivity of 0.0136 w/mK.

The SF6 molecule has a molecular mass of 146.06 units.

This gas has a sound velocity of 136 m/s, which is three times slower than air.

SF6’s Applications

Sulfur hexafluoride gas offers a wide range of applications as a dielectric gas for high voltage applications.

In the semiconductor industry, SF6 plasma is utilised as an etchant.

The inert gas SF6 is commonly utilised in the magnesium industry.

Because of its higher density than air, this gas is also utilised for amusement. It allows the voice to become substantially deeper.

Conclusion

The form of the SF6 molecule is symmetrical, with orthogonal geometry. Because the fluorine atom has a stronger electronegative value than the sulphur atom, it attracts the bound pair of electrons slightly towards itself.

As a result, the S-F bond becomes polar, resulting in a dipole moment, but the dipoles cancel each other out due to symmetry, making SF6 a nonpolar molecule.

So, if you have any questions about the polarity of SF6, feel free to post them in the comments area. We’ll get back to you as soon as we can.

Read more: Is BeCl2 a polar or nonpolar substance?

Misha Khatri
Misha Khatri is an emeritus professor in the University of Notre Dame's Department of Chemistry and Biochemistry. He graduated from Northern Illinois University with a BSc in Chemistry and Mathematics and a PhD in Physical Analytical Chemistry from the University of Utah.

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