Chloroform: Draw Accurate Lewis Structure

The chloroform molecule, also known as trichloromethane, has the chemical formula CHCl3. To draw the accurate Lewis structure for chloroform, we must first understand the basic rules of constructing Lewis structures. These rules include determining the total number of valence electrons in the molecule, drawing a skeleton structure that connects the atoms with single bonds, and then distributing the remaining electrons to satisfy the octet rule for each atom, except for hydrogen which needs only two electrons.

1. Determine the Total Number of Valence Electrons:

   • Carbon © has 4 valence electrons.
   • Hydrogen (H) has 1 valence electron.
   • Chlorine (Cl) has 7 valence electrons.
   • Since there are three chlorine atoms, we multiply the number of valence electrons in one chlorine atom by 3: 7 * 3 = 21.
   • Adding these together: 4 © + 1 (H) + 21 (3*Cl) = 26 valence electrons.

2. Draw the Skeleton Structure:

   • The carbon atom will be the central atom because it can form the most bonds.
   • The hydrogen atom will be attached to the carbon atom with a single bond.
   • The three chlorine atoms will also be attached to the carbon atom with single bonds.

3. Distribute the Remaining Electrons:

   • Each single bond represents 2 electrons, so the 4 single bonds (C-H and 3 C-Cl bonds) use 8 electrons.
   • Subtract these from the total: 26 - 8 = 18 electrons remaining.
   • Distribute these remaining electrons around the atoms to satisfy the octet rule:
     • The hydrogen atom already has 2 electrons (its full capacity), so it doesn’t need any more.
     • Each chlorine atom needs 8 electrons to satisfy the octet rule. Since each chlorine is already bonded to carbon with a single bond (2 electrons), they each need 6 more electrons. With 18 electrons remaining and 3 chlorine atoms, each chlorine can be given 6 electrons (3 * 6 = 18), which perfectly uses up all the remaining electrons.

4. Finalize the Lewis Structure:

   • Carbon © is bonded to one hydrogen (H) and three chlorines (Cl) with single bonds.
   • The hydrogen atom has two electrons (from the C-H bond).
   • Each chlorine atom has eight electrons: two from the bond with carbon and six as lone pairs.
   • The carbon atom has eight electrons as well: two from each of the four bonds (one to hydrogen and three to chlorine).

This description results in a Lewis structure where the carbon atom is central, bonded to one hydrogen atom and three chlorine atoms, with no lone pairs on the carbon but three lone pairs on each chlorine atom. This structure satisfies the octet rule for all atoms except for the carbon, which has four bonds but is in a stable configuration due to its ability to form these bonds. However, it’s worth noting that chloroform exhibits a slight positive charge on the carbon and a slight negative charge on each chlorine due to the electronegativity differences between carbon, hydrogen, and chlorine, but the Lewis structure provides a simplified view of the molecule’s electron configuration.