write the lewis structure for each molecule : a.CH2O b. C2Cl4
The correct Answer and Explanation is:
a. CH₂O (Formaldehyde)
Lewis Structure:
H
|
H – C = O
||
O
Explanation:
Formaldehyde (CH₂O) consists of one carbon (C), two hydrogen (H), and one oxygen (O) atom. To draw the Lewis structure, start by calculating the total number of valence electrons:
- Carbon (C) = 4 valence electrons
- Hydrogen (H) = 1 each × 2 = 2
- Oxygen (O) = 6
Total = 4 + 2 + 6 = 12 electrons
Carbon is the central atom because it can form the most bonds. The two hydrogens attach to carbon with single bonds (2 electrons each), using 4 electrons. Oxygen bonds to carbon, and to fulfill the octet rule, carbon and oxygen form a double bond. That uses 4 more electrons (a total of 8 now used).
Oxygen still needs to complete its octet, so we place two lone pairs (4 electrons) on oxygen. Carbon now has 4 bonds (8 electrons), and oxygen has 2 bonds and 2 lone pairs (also 8 electrons). The hydrogens have 2 electrons each, completing their duet. All atoms satisfy the octet or duet rule.
b. C₂Cl₄ (Tetrachloroethene)
Lewis Structure:
Cl Cl
\ /
C = C
/ \
Cl Cl
Explanation:
Tetrachloroethene (C₂Cl₄) has 2 carbon atoms and 4 chlorine atoms.
Valence electrons:
- Carbon = 4 × 2 = 8
- Chlorine = 7 × 4 = 28
Total = 8 + 28 = 36 electrons
Start by connecting the two carbon atoms with a double bond. Each carbon is then bonded to two chlorine atoms. This makes 4 bonds per carbon (satisfying the octet rule). Each Cl atom forms one single bond and needs 3 lone pairs (6 electrons) to complete its octet.
- 4 Cl atoms × 6 electrons = 24
- 2 C–C bonds = 4
- 4 C–Cl bonds = 8
Total used = 24 + 4 + 8 = 36 electrons
All atoms obey the octet rule. The Lewis structure is correct and shows that the carbon atoms are double-bonded and each bonded to two chlorine atoms.
