`PCl_3` has the shape of a trigonal pyramid, whereas `IF_5` has the shape of a suquare pyramid. Account for this difference.

Explanation

To account for the difference in shapes between PCl₃ (trigonal pyramidal) and IF₅ (square pyramidal), we can analyze their molecular structures through the concepts of hybridization and the presence of lone pairs.

### Step 1: Determine the Hybridization of PCl₃
1. **Identify the central atom**: In PCl₃, phosphorus (P) is the central atom.
2. **Count the valence electrons**: Phosphorus is in Group 15 and has 5 valence electrons.
3. **Count the number of bonded atoms**: There are 3 chlorine (Cl) atoms bonded to phosphorus.
4. **Apply the hybridization formula**:
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