To draw the Lewis structure for H2CO, we start by identifying the total number of valence electrons available in the molecule. Hydrogen (H) has 1 valence electron each, carbon (C) has 4, and oxygen (O) has 6. Therefore, the total number of valence electrons is:
- 2 H atoms × 1 = 2
- 1 C atom × 4 = 4
- 1 O atom × 6 = 6
- Total = 2 + 4 + 6 = 12 valence electrons
The structure can be outlined as follows:
H
|
H--C==O
In this structure, the carbon atom (C) is the central atom, bonded to two hydrogen atoms (H) and one oxygen atom (O). Carbon forms single bonds with each of the hydrogen atoms, while it forms a double bond with the oxygen atom.
This arrangement ensures that all atoms achieve a stable electronic configuration:
- Hydrogen atoms each have 2 electrons (a full outer shell for H).
- The carbon atom has 4 electrons from the two single bonds with H and 2 from the double bond with O, totaling 6 electrons.
- The oxygen atom has 4 electrons (from the double bond with C) plus 2 lone pairs, giving it a total of 8 electrons.
Thus, the Lewis structure is satisfactory as all atoms satisfy their bonding requirements and the total number of valence electrons is 12. This structure visually represents the connectivity and electron distribution within the formaldehyde molecule (H2CO).