bond angle in NH3 and CH4

用戶119701

2008-10-28 9:21 pm

The bond angle in NH3 is (smaller, larger)
than the bond angle in CH4 because
1. larger; nitrogen is larger than carbon.
2. smaller; nitrogen is smaller than carbon.
3. larger; the hybridization of nitrogen re-
sults in larger bond angles than the hybridiza-
tion of carbon.
4. larger; the bond angles in trigonal planar
molecules are larger than those in tetrahedral
molecules.
5. smaller; the bond angles in trigonal planar
molecules are smaller than those in tetrahe-
dral molecules.
6. smaller; the unshared pair of electrons
on nitrogen is more repulsive to the bonded
electron pairs.
7. smaller; the hybridization of nitrogen
results in smaller bond angles than the hy-
bridization of carbon.

回答 (1)

Uncle Michael

2008-10-28 11:03 pm

✔ 最佳答案

The answer is 6.

The N atom in NH3 and the C atom in CH4 are both sp3 hybridized, and the four sp3 orbitals are arranged tetrahedrally.

In CH4, the four identical C-H bonds are regularly tetrahedral, and thus the bond angle is 109.5o.

In NH3, the lone pair electrons and the three N-H bonds are arranged tetrahedrally. The lone pair is more diffused and thus more repulsive than the bond pairs. Consequently, the bond pairs are compressed to a smaller bond angle (107o) by the lone pair.

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