Which one is the wrong statement ?

Options

A. Anhydrous `AlCl_3` exists as `Al_2Cl_6` (dimer)
B. `Al_2Cl_6` contains `3c-4e^(-)` bonds
C. Anhydrous `AlCl_3` fumes in moist air
D. Anhydrous `AlCl_3` is ionic

Answer

To determine which statement is wrong regarding Aluminium Chloride (AlCl3), we will analyze each option based on the properties and bonding of AlCl3.

### Step-by-Step Solution:

1. **Understanding Aluminium and Chlorine:**
- Aluminium (Al) has an atomic number of 13, which means it has 3 valence electrons.
- Chlorine (Cl) has an atomic number of 17, which means it has 7 valence electrons.

2. **Octet Rule:**
- According to the octet rule, atoms tend to gain, lose, or share electrons to achieve a stable configuration of 8 valence electrons.
- Aluminium needs 5 more electrons to complete its octet, while each chlorine atom needs 1 electron.

3. **Formation of AlCl3:**
- Aluminium shares one electron with each of the three chlorine atoms, forming three covalent bonds.
- This sharing allows each chlorine atom to complete its octet, but Aluminium still has only 6 electrons around it, making it electron deficient.

4. **Dimerization of AlCl3:**
- To stabilize itself, AlCl3 can form a dimer, Al2Cl6, where two AlCl3 units bond together.
- In this dimer, Aluminium can achieve a stable configuration by forming additional bonds.

5. **Analyzing the Options:**
- **Option A:** "Anhydrous AlCl3 exists as Al2Cl6 dimer."
- This statement is correct.
- **Option B:** "Al2Cl6 contains 3-center 4-electron bond."
- This statement is also correct.
- **Option C:** "Anhydrous AlCl3 fumes in moist air."
- This statement is correct as AlCl3 hydrolyzes in moist air.
- **Option D:** "Anhydrous AlCl3 is ionic."
- This statement is incorrect. AlCl3 is covalent, not ionic, as it involves sharing of electrons rather than complete transfer.

### Conclusion:
The wrong statement is **Option D**: "Anhydrous AlCl3 is ionic."