Chem Explorers

Polar Nature and Stability of CHCl3: Understanding Molecular Properties

Polar Nature of CHCl3: Bond Type and Dipole Moment

When it comes to the polarity of molecules, the electronegativity difference between the atoms involved in the bond plays a crucial role. In the case of CHCl3, a covalent bond is formed between the carbon and hydrogen atoms, along with covalent bonds between the carbon and three chlorine atoms.

The electronegativity difference between the carbon and hydrogen atoms being 0.4, and between the carbon and chlorine atoms being 0.9 emphasizes that covalent bonds are formed in which atoms share electrons in a polar covalent bond. The polarity of CHCl3 is not only due to the bond polarity, but also the orientation of bonds relative to each other, in addition to the arrangement of the lone pair on the carbon atom.

The dipole moment is a measure of the strength of polarity of a molecule or bond. It is directly proportional to the magnitude of the product of the charges and the distance between them.

In the case of CHCl3, the electronegativity difference between the carbon and chlorine atoms causes the dipole moment vector of each C-Cl bond to point in the same direction, forming the direction of net dipole moment. The net dipole moment of CHCl3 has a value of 1.49D.

Geometrical or Molecular Shape of CHCl3

The molecular shape of a molecule is an important factor which determines its polarity. The molecular geometry of CHCl3 is tetrahedral, which means it has a central carbon atom surrounded by four atoms making it a symmetrical molecule.

Symmetrical molecules that have no lone pairs are non-polar meaning they have a net dipole of 0D. However, in the case of CHCl3, the geometry is asymmetrical due to the presence of a lone pair on the carbon atom.

As a result, the molecular shape is not purely tetrahedral and is distorted, causing the molecule to be polar.

Factors Influencing Polarity of CHCl3

Factors Influencing Polarity of CHCl3

  1. The first influential factor is the electronegativity of the atoms involved in the bond.

    The electronegativity difference between the carbon and chlorine atoms is greater than that between carbon and hydrogen atoms, resulting in greater polarity of C-Cl bond as compared to that of the C-H bond.

  2. The second factor is the dipole moment which is dependent on the difference in electron density between the atoms.

    The chlorine atom has higher electronegativity, resulting in the chlorine atom attracting the electrons in the bond towards itself. This causes an uneven distribution of electron density creating a polarity in the molecule with the chlorine atom having a slightly negative charge than the carbon atom.

  3. The molecular shape is a third factor that influences the polarity of CHCl3. The symmetrical shape of CHCl3 would have had a net dipole of 0D, but the asymmetrical shape due to the lone pair causes distortion, leading to a net dipole moment.


In conclusion, the polarity of CHCl3 is due to the differences in electronegativity between carbon and hydrogen, and between carbon and chlorine atoms creating polar covalent bonds. The molecular geometry being tetrahedral makes CHCl3 appear symmetrical, but its asymmetrical shape due to a lone pair on the carbon atom distorts the shape, making it polar.

Electronegativity, dipole moment and molecular shape all contribute to the polarity of CHCl3. Understanding the polarity of a molecule is important in understanding its chemical behavior and properties.

Formal Charge and Lewis Dot Structure of CHCl3

Formal charge is the charge that would exist on an atom of a molecule or polyatomic ion if all bonding electrons in the structure were shared equally between the bonded atoms. In the case of CHCl3, the calculation of formal charge on each atom helps to understand its electron distribution and molecular stability.

Calculation of Formal Charge

To calculate the formal charge, it is necessary to know the number of valence electrons in each atom in the molecule and then assign them according to their interactions. The formal charge for any individual atom in a molecule is calculated using the following equation:

Formal Charge = (Number of valence electrons in the free atom – Number of non-bonding electrons – 1/2 Number of bonding electrons)

Each atom in CHCl3 has 4 valence electrons (Carbon has 4, Hydrogen has 1, and Chlorine has 7).

Using the above equation, we can determine the formal charge on each atom in the molecule. Carbon: 4 – 0 – 8/2 = 0

Hydrogen: 1 – 0 – 0.5 = 0.5

Chlorine: 7 – 6 – 2/2 = 0

From the calculation, we can see that Carbon and Chlorine atoms in CHCl3 have zero formal charge, while Hydrogen atoms have a formal charge of 0.5, resulting from the asymmetric placement of the lone pair of electrons on the carbon atom.

The formal charge of CHCl3 is zero, indicating that it is a stable molecule.

Stability of Lewis Diagram

The Lewis diagram of CHCl3 shows the distribution of electrons between the atoms. To draw the Lewis diagram of CHCl3, we first count the total number of valence electrons of all the atoms.

In CHCl3, carbon contributes four valence electrons, while each chlorine atom contributes seven valence electrons while hydrogen contributes one valence electron. The total valence electron count for CHCl3 is therefore (4 + 3 7 + 1 ) = 26.

Using the valence electrons, we can start with a carbon atom as the central atom and drawing single bonds between carbon and chlorine, resulting in four single bonds. Electrons not used in forming bonds are placed on each of the atoms as lone pairs as shown:



H -C-Cl



Each chlorine atom receives 6 electrons as lone pairs while carbon shares electrons with each of the chlorine atoms. To check the stability of the Lewis diagram, we can calculate the formal charge for each atom as previously described.

In the above Lewis diagram of CHCl3, the Carbon atom has no formal charges as it has shared four electrons while having no lone pairs. Chlorine atoms also have no formal charges since they each have six valence electrons out of which four are shared by forming a bond and two are non-bonding electrons in the lone pair.

When calculating formal charge, it is desirable to have them as close as possible to zero. The closer the formal charge of an atom to zero, the more stable the electron distribution in the molecule.

In CHCl3, each atom has a formal charge of zero, confirming it as a stable molecule.


The formal charge and Lewis diagram are useful tools to understand the electron distribution in molecules, such as CHCl3. A molecule with zero formal charge possesses the most stability, which is essential for its chemical behavior.

These formulas help chemists understand the molecules better and predict their chemical reactions. In summary, the formal charge on each atom and the stability of the Lewis Diagram of CHCl3 help in understanding the distribution of electrons in the molecule, which is essential in understanding the polarity of the molecule and the chemical behavior of the molecule.

In conclusion, understanding the polar nature of molecules such as CHCl3 is essential in predicting their chemical behavior and properties. The electronegativity difference, dipole moment, and molecular geometry are significant factors that determine the polarity of a molecule.

The Formal Charge and Lewis Dot structures of CHCl3 further provide insight into its electron distribution and stability. The importance of these concepts in chemistry helps us in predicting the behavior of molecules and effective synthesis of various chemical structures.



  1. What factors determine the polarity of molecules?

    The electronegativity difference between atoms in the bond, dipole moment, and molecular geometry all play a role in determining the polarity of a molecule.

  2. How does a molecule’s formal charge relate to its stability? A molecule with a formal charge of zero typically has the most stable electron distribution, which is crucial in its chemical behavior.

  3. What is the significance of understanding the polar nature of molecules?

    Understanding a molecule’s polarity helps predict its chemical reactions and properties, making it easier to design effective chemical synthesis strategies.

  4. How can Lewis diagrams help chemists understand molecules? Lewis diagrams provide insight into the electron distribution of molecules and their stability, allowing chemists to predict their chemical behavior.

  5. Why is understanding the behavior of molecules essential in chemistry?

    Understanding the behavior of molecules allows chemists to make informed decisions about compounds’ synthesized nature and reactions, ultimately advancing the field of chemistry.

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