Nitromethane, with the molecular formula CH3NO2, is an interesting organic compound. To draw the Lewis structure for nitromethane, we need to consider its atoms and how they bond.
First, we begin by counting the total number of valence electrons available. Carbon (C) has 4 valence electrons, hydrogen (H) has 1 valence electron, nitrogen (N) has 5 valence electrons, and each oxygen (O) has 6 valence electrons. With the molecular formula CH3NO2, the total is:
- C: 4
- H: 3 x 1 = 3
- N: 5
- O: 2 x 6 = 12
Adding these up, we get: 4 + 3 + 5 + 12 = 24 valence electrons.
Next, we begin arranging the atoms. The carbon atom is the central atom because it can form four bonds. Thus, we place the nitrogen atom attached to carbon because it forms a bond with carbon and has further bonds with oxygen:
O
||
H - C - N
|\n H
|
H
Now we need to create bonds to the nitrogen atom. The nitrogen atom will form a double bond with one oxygen atom (to satisfy nitrogen’s valence requirement), while it will have a single bond with another oxygen atom. This oxygen will have a full octet and will carry a formal negative charge:
O-
||
H - C - N
|
O
Now let’s account for the formal charges. For the carbon atom, it has four bonds (4 electrons) and no lone pairs, giving it a formal charge of 0. For the nitrogen, it has three bonds (6 electrons) and 0 lone pairs, also giving it a formal charge of 0. The negatively charged oxygen has one bond (2 electrons) and 3 lone pairs (6 electrons), making its formal charge -1. The positively charged nitrogen and negatively charged oxygen means the overall charge of the molecule is neutral.
Finally, placing all this together, we get the complete Lewis structure for nitromethane:
O-
||
H - C - N+
|
H
|
H
This structure accurately reflects the bonding in nitromethane, with bonds and lone pairs clearly shown, along with minimized formal charges on all atoms involved.