The chemical formula CHCl3 represents Chloroform. It is also known as Trichloromethane. Chloroform is a clear, colorless liquid that possesses a pleasant odor. It is nonflammable and is denser than water. It is generally prepared by the chlorination of methane. Chloroform first found use as an inhalation anesthetic in the 19th century. These days, it is produced industrially as a precursor to making Teflon. Chloroform also finds use as a refrigerant in many parts of the world. This refrigerant- HCFC22, contributes to the depletion of the ozone layer. Chloroform also occurs naturally, with about 660,000 tons released per year from biotic and abiotic sources. It may also be released into the air due to Chlorination due to Chlorine’s presence in swimming pools and other water sources. It has the following properties:
| Name of the molecule | Trichloromethane (CHCl3) |
| No. of valence electrons | 4 + 1 + (3 x 7) = 26 valence electrons |
| Hybridization of the central atom | sp3 |
| Bond Angles | 109.5° |
| Molecular Geometry of CHCl3 | Tetrahedral Molecular Geometry |
Contents
CHCl3 Valence Electrons
Chloroform or Trichloromethane comprises three Chlorine atoms, a Carbon atom and a hydrogen atom. Carbon is in group 4 of the periodic table with the electronic configuration [He] 2s22p2. Therefore, the Carbon atom contributes 4 x 1 = 4 valence electrons Hydrogen has an electronic configuration of 1s1 and therefore contributes 1 valence electron. Being in group 7 of the periodic table, Chlorine has seven valence electrons with a valency of -1. Chlorine’s electronic configuration is given by [Ne]3s23p5. Therefore, the three Chlorine atoms contribute 7 x 3 = 21 valence electrons. Now, the total number of valence electrons available in CHCl3 is given by: 4[C] + 1[H] + 21[Cl] = 26 valence electrons.
CHCl3 Lewis Structure
Although Hydrogen is the least electronegative, it remains on the outside. Therefore, Carbon acts as the central atom because it is less electronegative than Chlorine. The atoms are arranged as shown in the figure, with the valence electrons placed in between to form covalent bonds. We then proceed to fulfill octets for the outermost atoms, i.e., Chlorine and Hydrogen. As shown in the figure, the remaining 18 valence electrons go to each of the Chlorine atoms to fulfill the octet rule. The Lewis Structure and dot structure is given below: The Lewis Structure is stable due to all of the outermost shells being filled for each element. Hydrogen needs only two electrons to fill its outermost shell.
CHCl3 Hybridization
Well, this one’s pretty simple. The CHCl3 molecule comprises three chlorine atoms and a Hydrogen atom; all pulled together by the central carbon atom. There are four covalent bonds present- 3 C-Cl bonds and 1 C-H bond. This structure gives rise to four electron domains. As such, the hybridization of the central Carbon atom is sp3.
CHCl3 Bond Angles
According to the VSEPR theory, the Chlorine atoms all repel each other forming a tetrahedral shape. As such, the bond angle of CHCl3 is 109.5°.
CHCl3 Molecular Geometry and Shape
From the stable Lewis structure above, there are no lone pairs. According to the VSEPR theory, the Chlorine atoms repel each other as much as they can. With Hydrogen on the top and Chlorine atoms below, the molecular shape is shown in the figure. Therefore, CHCl3 has a Tetrahedral molecular geometry. Concluding Remarks Let’s quickly summarize the salient features of CHCl3
- CHCl3 consists of a single Carbon atom, a single Hydrogen atom, and three Chlorine atoms.
- Carbon acts as the central atom in its most stable state and forms four covalent bonds with the Hydrogen atom and the three Chlorine atoms.
- Due to the presence of 4 electron domains and its steric number being 4, the hybridization of CHCl3 is given by sp3.
- CHCl3 has a Tetrahedral molecular structure and has bond angles of 109.5°.
