Sulfur Hexafluoride having its chemical formula SF6 is an inorganic compound that is colorless in appearance. It is an odorless, non-toxic, and non-flammable gas. It is considered to be an extreme greenhouse gas. Many students may have a query about whether SF6 is polar or not. In this article, I will answer this question and will cover the surrounding topics too.
So, Is SF6 Polar or Nonpolar? SF6 is a nonpolar compound in nature because as per VSEPR theory six fluorine atoms are arranged symmetrically with the sulfur atom such that dipole moment of S-F bond gets canceled out making the SF6 a nonpolar compound.
SF6 has its IUPAC name Sulfur hexafluoride and it is considered as an extreme gas responsible for the greenhouse effect.
It is a colorless gas with no toxicity. It is also not flammable in nature.
If we talk about the conductivity of SF6, it is an excellent insulator. It does not conduct electricity.
In a molecule of sulfur hexafluoride, it consists of one sulfur atom and six fluorine atoms. The sulfur atom is the central atom connected with the six fluorine atoms.
The four fluorine atoms are covalently bonded in one plane such that it forms a square and two fluorine atoms form covalent bonds axial to the molecule.
As a result, the shape of the SF6 molecule is formed as octahedral geometry. This geometrical structure is symmetrical in shape.
The sulfur atom has 6 valence electrons and fluorine has 7 valence electrons in its outermost shell.
The S-F covalent bond stabilizes each other forming a stable SF6 molecule that has a symmetrical geometrical shape.
The electronegativity of fluorine is 3.98 whereas the electronegativity of sulfur is 2.58. Therefore, there is a difference between the electronegativity of both atoms.
Due to this difference, the unequal sharing of bonded electrons by both atoms occur.
Electronegativity is the potential of an atom to attract the bonded pair of electrons towards it.
So, the more electronegative atom tends to attract the bonded electron pair more towards itself.
Similarly, the fluorine atom attracts the bonded pair of electrons slightly towards itself and gains a partial negative charge. And in return, the sulfur atom gains a partial positive charge.
Due to polarity in the S-F bond, the dipole moment in the bond is generated.
What are Polar and Nonpolar Molecules?
The molecules have atoms held by the types of different forces like ionic, covalent, metallic, and hydrogen bonds.
Ionic and covalent bonds are considered to be the strongest in all the bonds. These two bonds are commonly used in chemical compounds.
Ionic bonds are formed in the molecules in which the atoms are oppositely charged. The oppositely charged atoms get attracted to each other by the ionic forces. The electrolytic compounds like NaCl, KCl are the few examples of such compounds.
The covalent compounds are the compounds in which the atoms share electrons of each other to get stabilized.
The covalent bonds can be polar and nonpolar based upon the electronegativity of the atoms.
Nonpolar molecules: These are the molecules in which both atoms share an equal portion of the bonded electron pair. It means, both atoms covalently bonded have an equal distribution of charge on them.
These atoms do not have differences in their electronegativity and therefore share the larger proportion of bonded electron pair.
The geometrical shape of such atoms is also symmetric.
Polar Molecules: These molecules are those in which both atoms share an unequal proportion of bonded electron pairs. Both atoms have unequal charge distribution on them.
These atoms have differences in their electronegativity values. More electronegative gains partial negative charge because it attracts the bonded electrons more towards itself.
Why is SF6 a nonpolar compound?
Sulfur hexafluoride is made up of six fluorine atoms and a single sulfur atom. The electronegativity of fluorine is greater than sulfur due to which the S-F bond becomes polar.
Therefore, the S-F bond also gives a non zero dipole moment.
The dipole moment of a chemical compound is the measure of its polarity. Greater is the dipole moment, more is the polarity of that compound.
It should be important to note that if there are polar bonds within the molecule and the shape of the molecule is symmetrical then the dipoles get canceled out with each other due to symmetry of the molecule.
Similarly, the six dipoles of S-F bonds in SF6 molecule get canceled out with each other resulting in a nonpolar SF6 molecule.
Although the polar bonds exist within the SF6 molecule, the complete molecule is nonpolar in nature.
Factors affecting the polarity of the compound
Electronegativity: Greater the electronegativity of an atom, more is the strength of attracting the bonded electrons.
Therefore, the polarity of a molecule is directly proportional to the difference between the electronegativity of atoms.
Dipole moment: It is the measure of determining the level of the polarity of a chemical compound. More the dipole moment of a molecule, greater is its polarity.
The polarity of a molecule is directly proportional to its dipole moment.
The dipole moment is a vector quantity, it has magnitude as well as direction.
Geometrical shape: The geometrical shape of a molecule is an important factor in determining the polarity of a molecule. The molecules that are symmetrical in shape have their zero dipole moment.
In case, if molecules have a polar bond within it, their dipole moment gets canceled out with each other making the molecule a nonpolar.
The Geometrical Structure of SF6
If we talk about the geometrical shape of sulfur hexafluoride, there are six S-F covalent bonds. Four of them are in one plane making a square planar and two bonds are axial to the square plane.
As a result, the octahedral shape of the molecule is formed. All the F-S-F is perpendicular to each other.
All the six valence electrons participate in the six covalent bonds formed leaving behind no lone pair.
Below is the diagram of the geometrical structure of SF6
Properties of SF6
- The atomic number of sulfur hexafluoride is 16 and its electronic configuration is 2, 8, 6 i.e. 1S2 2S2 2P6 3S2 3P4
- This is colorless and highly non-flammable.
- The density of sulfur hexafluoride gas at a temperature of 20 degrees Celcius is 6.14 kg/m3.
- The thermal conductivity of this gas is 0.0136 w/mK.
- The molecular mass of the SF6 molecule is 146.06 units.
- The sound velocity in this gas is 136 m/s that is 3 times less than that in air.
- The refractive index of SF6 gas is 1.000783.
Uses of SF6
- Sulfur hexafluoride gas has its great use as an excellent dielectric gas for high voltage applications.
- The plasma of SF6 is used in the semiconductors industries as an etchant.
- The SF6 is an inert gas that is used widely in magnesium industries.
- This gas is also used for entertainment purposes, it causes the voice to become significantly deeper because of its higher density than air.
The molecule of SF6 is symmetrical in shape ie; orthogonal geometry. The fluorine atom is higher electronegative than sulfur atom due to which the fluorine atom attracts the bonded pair of electron slightly towards itself.
As a result, the S-F bond becomes polar and results in a dipole moment but due to symmetry, the dipoles get canceled out with each other making the SF6 a nonpolar molecule.
So guys, if you have any doubts regarding the polarity of SF6, you can ask them in the comment section. We will reach out to you as soon as possible.