What is the Lewis structure of CH2O and what intermolecular forces are present?
The correct answer and explanation is:
The Lewis structure of CH₂O (formaldehyde) is as follows:
- Carbon (C) is the central atom since it is the least electronegative element.
- Two hydrogen (H) atoms are bonded to carbon. Each hydrogen forms a single bond with carbon.
- The carbon atom forms a double bond with the oxygen (O) atom. Oxygen has two lone pairs of electrons, which are not involved in bonding.
The structure can be represented as:
H - C = O
|
H
Explanation:
- Valence Electrons: Carbon has 4 valence electrons, hydrogen has 1 each, and oxygen has 6 valence electrons.
- Carbon forms 2 bonds with hydrogen and a double bond with oxygen, using up all 4 of its valence electrons.
- Oxygen has 2 bonds with carbon, leaving 2 lone pairs of electrons on the oxygen atom.
- Hydrogen atoms each contribute 1 electron, forming 2 single bonds with carbon.
- Bond Angles: In the Lewis structure of CH₂O, the bond angles around carbon are approximately 120°, as it is a trigonal planar molecule with sp² hybridization.
- Intermolecular Forces:
- Dipole-Dipole Interactions: CH₂O is a polar molecule because of the difference in electronegativity between carbon, hydrogen, and oxygen. The oxygen atom is more electronegative, creating a partial negative charge (δ-) on oxygen and a partial positive charge (δ+) on carbon.
- London Dispersion Forces: These are weak forces that occur due to temporary dipoles in all molecules, including CH₂O. They are especially noticeable in larger molecules, but they still exist in formaldehyde.
Overall, the intermolecular forces present in CH₂O are dipole-dipole interactions due to its polarity and London dispersion forces, which are always present in all molecular compounds.