Question

32
the best lewis structure for ethyne (c2h2; commonly called \acetylene\) has * (0.5 points)
2 single bonds, 1 triple bond, and 1 lone pair.
2 double bonds and 2 lone pairs.
2 single bonds, 1 triple bond, and no lone pairs.
2 single bonds, 1 double bond, and 2 lone pairs.

Explanation:

• Valence electrons: Carbon has 4 valence electrons and hydrogen has 1. For \(C_2H_2\), total valence electrons \(= 2\times4 + 2\times1=10\).
• Bonding: Each hydrogen forms a single bond with carbon (\(C - H\)). The two carbon atoms form a triple bond (\(C\equiv C\)).
• Lone pairs: In \(H - C\equiv C - H\), all valence electrons are used in bonding. There are no lone pairs as each carbon has 4 bonds (satisfying the octet rule) and each hydrogen has 1 bond (satisfying the duet rule).

Answer:

2 single bonds, 1 triple bond, and no lone pairs.