So, is SF4 Polar or Nonpolar? SF4 (Sulfur tetrafluoride) is polar in nature as sulfur atom consists of a lone pair on it due to which the shape of the molecule becomes asymmetric ie; seesaw. Moreover, Fluorine is more electronegative than Sulfur due to which the overall charge distribution of a molecule is uneven resulting in a polar molecule and give 0.632 D dipole moment. Sulfur tetrafluoride is a chemical compound known by its systematic IUPAC name as Sulfur(IV) fluoride. This compound is rich in fluorine therefore considered as one of the best fluorinating agents. The molecular mass of SF4 is 108.07 g/mol. It is considered as below Mol mass of SF4 = 1 * (32) Mol mass of S + 4 * (18.9) Mol mass of F = 108.07 g/mol. If we talk about the chemical composition of sulfur tetrafluoride, it consists of 1 sulfur atom and 4 fluorine atoms. The sulfur atom has 6 valence electrons and out of which 4 electrons participate in the sigma bonds formed with 4 fluorine atoms and 2 electrons form a lone pair. Fluorine has 7 valence electrons and needs 1 more electron to complete its octet and it shares 1 electron from sulfur leaving behind 1 lone pair on sulfur atom. As a result, there occurs electronic repulsion between the lone pair and bond pairs, and the geometry of the molecule formed is seesaw. Due to asymmetric molecular shape, the distribution of charges across the molecules of SF4 is uneven. In addition to this, the electronegativity of fluorine and sulfur differs, The electronegativity of sulfur is 2.58 and that of fluorine is 3.98. Being more electronegative, fluorine attracts the bonded electron pair with more influence and gains a partial negative charge and other atom gains partial positive charge.
Polar and Nonpolar Molecules
There are different forms of forces that bind the molecules. These forces include ionic bond, covalent bond, metallic bond, and hydrogen bonding. The molecules that are covalently bonded can be polar and nonpolar. Let us discuss what differences occur among polar and nonpolar molecules. Polar Molecules: These molecules do not have a uniform distribution of charge across its atoms. The dipole moment of these molecules is always equaled to non zero. The electronegativity of atoms in these molecules is unequal due to which atoms have an unequal influence on the bonded electron pair. The covalent bond formed by two atoms tends to be polar if they have a different value of their electronegativity. It is usually seen that the geometry of polar molecules is asymmetrical. Some of the examples of these molecules are H2O, SO2. You can check out the reason for the polarity of SO2. Nonpolar Molecules: The molecules in which there exists a uniform charge distribution over its atoms are known as nonpolar molecules. The value of electronegativity of two atoms that form a nonpolar covalent bond is equal because both atoms will have an equal share of a bonded electron pair. It is generally observed that the geometry of nonpolar molecules is symmetrical. Few examples of such molecules are XeF2, O2, etc. You can check out the reason for the non-polarity of XeF2.
Why is SF4 Polar?
As discussed above, the geometry of a molecule is an important factor in indicating its polarity. And if we check the VSEPR diagram, the sulfur atom consists of 1 lone pair on it due to which the shape of SF4 becomes asymmetric ie; seesaw. The fluorine is more electronegative than sulfur ie; fluorine attracts the bonded electron pair slightly more towards itself and gains partial negative charge and sulfur atom gains partial positive charge. In this way, the charge distribution becomes irregular on the atoms of the SF4 molecule. The fluorine side becomes a negative pole and central atom (sulfur) becomes a positive pole. The value of the dipole moment of SF4 is 0.632 D.
Points to check Polarity of a compound
Electronegativity: the term electronegativity of an atom is its strength to attract the bonded pair of electron. Greater the electronegativity of an atom, the more it attracts the electrons to its side. If there is a difference between the electronegativity of two atoms that form a molecule, the molecule will result in a polar molecule because its atoms will have an unequal share of the charge. Therefore, the polarity of a molecule is directly proportional to the difference between their electronegativity and vice versa. But in the case of symmetric geometry, the molecules having unequal electronegativity can also be nonpolar because in such cases, the dipoles are canceled by each other due to symmetric shape. Geometrical shape: The geometrical shape of a molecule is also an important parameter to check if a compound is polar or not. The polar molecules are generally seen with asymmetric geometry because they have unequal charge distribution. Whereas the nonpolar molecules have symmetric geometry. There is a possibility of a molecule to be nonpolar even if it consists of atoms with different electronegativity because in such cases the dipoles of such bonds get canceled by each other due to symmetric shape. Below is the shape of the geometrical structure of the SF4 molecule.
Dipole Moment: The dipole moment of a molecule is a measure of its polarity. The polarity of a molecule is directly proportional to its dipole moment. It is calculated as the product of charge on atoms and the distance between the centers of positive and negative charges. D = Q * R
Properties of SF4
Sulfur tetrafluoride exists in the gaseous state at room temperature. It is colorless in appearance and considered highly toxic. At a temperature of −78 °C, its density is 1.95 g/cm3. The melting point of this substance is −121.0 °C and its boiling point is −38 °C. The atmospheric pressure of this substance is 10.5 atm at a temperature of 22°C. The molecular shape of SF4 is Seesaw. The dipole moment of SF4 is around 0.632 D.
Uses of SF4
In organic synthesis, sulfur tetrafluoride is considered as a reagent for preparing organofluorine compounds. It is widely used to fluorinate carbonyl and hydroxyl groups. It is also used in the biological field in the manufacturing of high-end liquid crystal material medicine. It is also used for the manufacturing of pesticides.
Conclusion
Sulfur tetrafluoride consists of 1 sulfur and 4 fluorine atom connected via sigma bonds. The sulfur atom consists of 1 lone pair. As a result, due to lone pair and bond pair electronic repulsion, the shape of molecules becomes asymmetric ie; Seesaw. Secondly, there is enough difference between the electronegativity of fluorine and sulfur atoms due to which fluorine gains partial negative charge and the sulfur atom gains partial positive charge. Due to these factors, sulfur tetrafluoride is a polar molecule. So guys, if you feel any query, feel free to ask your queries through comments. I will reach out to you quickly.
