Which of the following does not follow the octet rule ? .

Options

A. `CO_(2)`
B. `PCl_(3)`
C. `ICl`
D. `ClF_(3)`

Explanation

To determine which of the given compounds does not follow the octet rule, we will analyze each compound one by one. The octet rule states that atoms tend to form bonds in such a way that they have eight electrons in their valence shell, achieving a stable electronic configuration similar to that of noble gases.

### Step-by-Step Solution:

1. **Identify the Compounds**: The compounds we need to analyze are CO₂, PCl₃, ICl, and ClF₃.

2. **Analyze CO₂ (Carbon Dioxide)**:
- Carbon (C) has 4 valence electrons and needs 4 more to complete its octet.
- Each oxygen (O) has 6 valence electrons and needs 2 more to complete its octet.
- In CO₂, carbon forms double bonds with each oxygen atom, sharing a total of 4 electrons (2 from each O).
- Result: Both carbon and oxygen achieve an octet. **CO₂ follows the octet rule**.

3. **Analyze PCl₃ (Phosphorus Trichloride)**:
- Phosphorus (P) has 5 valence electrons and needs 3 more to complete its octet.
- Each chlorine (Cl) has 7 valence electrons and needs 1 more to complete its octet.
- In PCl₃, phosphorus forms single bonds with three chlorine atoms, sharing 3 electrons (1 from each Cl).
- Result: Both phosphorus and chlorine achieve their octets. **PCl₃ follows the octet rule**.

4. **Analyze ICl (Iodine Monochloride)**:
- Iodine (I) has 7 valence electrons and needs 1 more to complete its octet.
- Chlorine (Cl) also has 7 valence electrons and needs 1 more to complete its octet.
- In ICl, iodine forms a single bond with chlorine, sharing 1 electron.
- Result: Both iodine and chlorine achieve their octets. **ICl follows the octet rule**.

5. **Analyze ClF₃ (Chlorine Trifluoride)**:
- Chlorine (Cl) has 7 valence electrons and needs 1 more to complete its octet.
- Each fluorine (F) has 7 valence electrons and needs 1 more to complete its octet.
- In ClF₃, chlorine forms single bonds with three fluorine atoms, sharing 3 electrons (1 from each F).
- Result: Chlorine ends up with 10 electrons in its valence shell (7 from itself + 3 from fluorine), exceeding the octet rule. **ClF₃ does not follow the octet rule**.

### Conclusion:
The compound that does not follow the octet rule is **ClF₃**.

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