Draw the Lewis Structure for H2CO: How Many Bonds and Non-Bonding Pairs Are Around the Central Atom? What Is the Shape of This Molecule?

To draw the Lewis structure for H₂CO (formaldehyde), follow these steps:

1. Count the total number of valence electrons: Carbon (C) has 4, each Hydrogen (H) has 1, and Oxygen (O) has 6. So, 4 + (2 × 1) + 6 = 12 valence electrons.
2. Place the least electronegative atom in the center, which is Carbon (C).
3. Connect the Carbon atom to the two Hydrogen atoms and the Oxygen atom using single bonds. This uses 6 electrons (2 for each bond).
4. Place the remaining 6 electrons around the Oxygen atom to complete its octet. This forms two lone pairs on the Oxygen atom.

The Lewis structure of H₂CO shows that the central Carbon atom is bonded to two Hydrogen atoms and one Oxygen atom. The Oxygen atom has two lone pairs of electrons.

Number of Bonds and Non-Bonding Pairs:

• The central Carbon atom forms 3 bonds (two with Hydrogen and one with Oxygen).
• There are no non-bonding pairs around the central Carbon atom.
• The Oxygen atom has 2 non-bonding pairs (lone pairs).

Shape of the Molecule:

The shape of H₂CO is trigonal planar. This is because the central Carbon atom has three regions of electron density (two single bonds with Hydrogen and one double bond with Oxygen), and no lone pairs. The molecule is flat, with bond angles of approximately 120°.