At room temperature and atmospheric pressure, difluoromethane (CH2F2) is a colourless gas. It has applications in endothermic processes such as air conditioners, refrigerators, and fire extinguishers since it is thermally stable. Due to its low boiling point (-52 °C) and melting point (-136 °C), difluoromethane can cause skin harm (Frostbite) when it comes into contact with the skin.
Is CH2F2 polar or nonpolar, then? Despite its symmetrical structure (tetrahedral geometry), difluoromethane (CH2F2) is polar. The substantial difference in electronegativity of the C-F bond causes polarity. Because the C-F bond is polar, it results in the development of a strong dipole. As a result, the molecule will have a net dipole moment with the fluorine atom having a negative pole. The polar character of the CH2F2 molecule is the result of this.
Let’s take a closer look at the polar properties of the CH2F2 molecule.
First and foremost, we must comprehend the distinction between polar and nonpolar molecules. Then we’ll look at the components that influence the polarity of the molecule. Following that, we’ll look at how CH2F2 is a polar molecule.
Let’s begin with the fundamentals of chemical bonding, namely, ionic and covalent bonds.
Covalent Bond vs. Ionic Bond
Except for noble gases, elements do not exist in their atomic form. As a result of the attraction between two similar or dissimilar atoms, a chemical bond is formed.
Between two atoms, a chemical bond is created by sharing electron pair(s) or transferring electron(s) from one atom to another. Valence electrons are the electrons that are involved in the creation of chemical bonds.
The valence electrons are found in an atom’s outermost shell, or valence shell. Ionic and covalent bonds are two types of chemical bonds found in molecules.
Ionic Bond: An ionic bond is created when one atom donates its electron to another, resulting in the formation of cation and anion, respectively. When two atoms have a big difference in electronegativity and so cannot share an electron pair, an electron transfer takes place.
The electrostatic force of attraction holds two atoms together in an ionic connection.
When two atoms share the same electron pair, they form a covalent connection (s). Single, double, and triple bonds are formed by the sharing of one, two, or three electron pairs between two atoms, respectively.
The difference in electronegativity of two atoms determines whether the covalent bond is polar or nonpolar.
Polar Covalent Bond: A polar covalent bond is created when two atoms share electron pairs unequally due to their electronegativity values being different. According to the Pauling scale, the electronegativity difference should be more than 0.4.
Nonpolar Covalent Bond: A nonpolar covalent bond is created when two atoms with the same electronegativity or a very minor variation in electronegativity, which are involved in the formation of the chemical bond, share the same electron pair.
Depending on additional conditions, such as those discussed later in this article, polar covalent bonds can lead to the development of a polar or nonpolar molecule.
What are polar and nonpolar molecules, exactly?
Molecules, Polar and Nonpolar
There is a significant discrepancy in the electronegativity values of atoms in Polar Molecules. A net dipole moment exists in a polar molecule.
There may or may not be a significant variation in the electronegativity values of atoms in nonpolar compounds. However, the nonpolar molecule’s net dipole moment will be zero.
In a polar solvent, polar molecules dissolve, while nonpolar molecules dissolve in a nonpolar solvent.
As previously stated, the polar covalent bond can produce both polar and nonpolar molecules. How will we know if the molecule is polar or nonpolar then?
Other factors that create polarity in the molecule must be discussed first.
Polarity in Molecules: Factors Affecting It
Three factors influence the polarity of molecules.
The molecule’s structure
The molecule’s net dipole moment
The charge distribution around the centre atom
These aspects of the difluoromethane (CH2F2) molecule will be discussed.
The carbon atom is the centre atom in the CH2F2 molecule, which is surrounded by hydrogen and fluorine atoms.
You must consult the article on the CH2F2 Lewis structure for this.
The first step is to determine whether or not the C-H and C-F bonds are polar or nonpolar covalent bonds.
As a result, we must examine the difference in electronegativity between these bonds.
The Pauling Scale says that
The carbon atom’s electronegativity is 2.55.
The hydrogen atom’s electronegativity is 2.20.
The fluorine atom has an electronegativity of 3.98.
The difference in electronegativity of the C-H bond in the CH2F2 molecule is 2.55 – 2.20 = 0.35.
The difference in electronegativity of the C-F bond in the CH2F2 molecule is 3.98 – 2.55 = 1.40.
An electronegativity difference of at least 0.4 is required for a covalent bond to be a polar covalent bond. As a result, the CH2F2 molecule’s C-H and C-F bonds are nonpolar (or mildly polar) and polar covalent bonds, respectively.
The polar C-F bond in the CH2F2 molecule functions as a dipole, with partial positive and partial negative charges on the carbon and fluorine atoms, respectively. As a result, the dipole moment of the C-F bond will exist.
The dipole moment is calculated as follows:
The dipole moment is equal to the charge on the atoms multiplied by the distance between the atoms.
It’s a vector quantity, which means the dipole’s direction will go from positive to negative. The C-F bond has a dipole moment of 1.51 Debye (D) oriented towards the fluorine atom.
The polarity of a covalent bond is measured by the dipole moment. The polarity of a covalent bond is proportional to its dipole moment.
The CH2F2 molecule matches the AX4 geometry well, according to the Valence shell electron pair repulsion theory (VSEPR) and Valence bond theory (VBT), and hence the geometry of CH2F2 is tetrahedral, which is a symmetrical shape.
The symmetrical form indicates that if a molecule has all C-H or C-F bonds, the net dipole moment will be zero since the dipoles cancel each other out.
The C-H bond’s weak dipole cannot counteract the effect of the C-F bond’s strong dipole. As a result, despite its symmetrical tetrahedral shape, the difluoromethane molecule will have a net dipole moment.
The vector addition of the dipole moments of two polar covalent bonds, namely the C-F bonds, can be used to compute the net dipole moment of the difluoromethane molecule.
The difluoromethane molecule’s net dipole moment is 1.97 D, indicating the polar nature of the difluoromethane molecule. According to the vector addition of two C-F bonds, the net dipole moment in the difluoromethane molecule will be directed from the carbon atom to the space between two C-F bonds.
All of the above considerations point to difluoromethane being a polar molecule. As a result, intermolecular forces between difluoromethane molecules will be dipole-dipole.
The colourless gas difluoromethane is an essential haloalkane used in refrigerators, air conditioners, and fire extinguishers.
The polar nature of the difluoromethane molecule has been investigated here.
In a nutshell, the difluoromethane molecule possesses symmetrical geometry, or tetrahedral geometry, indicating a symmetric charge distribution around the centre element, carbon. The electronegativity difference between the C-F bond and the electronegativity difference between the C-F bond and the electronegativity difference between the C-F bond and the electronegativity difference between the C-F bond and the electronegativity difference between the C-F As a result, the C-F bond will be a dipole, with the carbon atom’s positive pole and the fluorine atom’s negative pole.
Because there are two C-F bonds, the net dipole moment can be calculated by multiplying the vector sum of the two C-F bonds by 1.97 D.
The polar character of the difluoromethane molecule is suggested by the net dipole moment and the substantial electronegativity difference of the C-F bond in the molecule.
I hope you grasped the polarity notion in the difluoromethane molecule. If you have any further questions, please do not hesitate to inquire.
Thank you so much for taking the time to read this.