Explain why bond angle of `NH_(3)` is greater than `NF_(3)` while bond angle of `PH _(3)` is less than that of `PF _(3),`

Explanation

To explain why the bond angle of NH₃ is greater than that of NF₃, while the bond angle of PH₃ is less than that of PF₃, we can break down the reasoning into the following steps:

### Step 1: Understanding the Structure of NH₃ and NF₃
- **NH₃ (Ammonia)** has a trigonal pyramidal shape due to one lone pair of electrons on nitrogen and three hydrogen atoms bonded to it.
- **NF₃ (Nitrogen Trifluoride)** also has a trigonal pyramidal shape, with one lone pair on nitrogen and three fluorine atoms bonded to it.

### Step 2: Analyzing the Lone Pair Effect
- In NH₃, the lone pair on nitrogen has a higher percentage of s-character compared to the p-character due to the presence of hydrogen, which is less electronegative. This higher s-character leads to stronger lone pair-bond pair repulsions, which pushes the hydrogen atoms further apart, resulting in a larger bond angle.
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