To construct the Lewis structure for acetaldehyde (CH3CHO), we first need to determine the total number of valence electrons. Carbon (C) has 4 valence electrons, oxygen (O) has 6, and hydrogen (H) has 1. Acetaldehyde has two carbons, one oxygen, and four hydrogens, giving us:
- 2 (from C) + 1 (from O) + 4 (from H) = 2(4) + 6 + 4 = 18 valence electrons.
The skeletal structure is CH3-C(=O)-H, which connects the atoms based on their bonding preferences. The Lewis structure is drawn as follows:
H H | | H-C - C=O | | H H
In this structure, each carbon forms four bonds: the first carbon (CH3) is bonded to three hydrogen atoms and one carbon. The second carbon is double-bonded to oxygen and bonded to one hydrogen atom.
Next, considering the three-dimensional structure: the first carbon (C1) of the CH3 group is tetrahedral, leading to bond angles of approximately 109.5° due to sp3 hybridization. The second carbon (C2), which is involved in a double bond with oxygen, is trigonal planar, thus having bond angles of about 120° due to sp2 hybridization. The oxygen atom has a bent shape because of its two lone pairs of electrons, which affects how the surrounding bonds orient themselves.
In summary:
- C1 has sp3 hybridization with bond angles of approximately 109.5°.
- C2 has sp2 hybridization with bond angles of approximately 120°.
This comprehensive depiction of the Lewis structure and the three-dimensional arrangement of acetaldehyde illustrates the molecule’s bonding interactions and geometry in a clear manner.