The compound that is not a Lewis acids is

Options

A. `BF_(3)`
B. `AICI_(3)`
C. `BeCI_(2)`
D. `SnCI_(4)`

Explanation

To determine which compound is not a Lewis acid among the given options, we need to understand the definition of a Lewis acid. A Lewis acid is defined as a substance that can accept an electron pair, which typically means it has an empty orbital or a vacant octet.

Let's analyze the compounds given in the question step-by-step:

### Step 1: Identify the Compounds
We have four compounds to consider:
1. BF3
2. AlCl3
3. BaCl2
4. SnCl4

### Step 2: Analyze Each Compound
1. **BF3 (Boron Trifluoride)**:
- Boron has only six electrons in its valence shell and can accept a pair of electrons to complete its octet.
- **Conclusion**: BF3 is a Lewis acid.

2. **AlCl3 (Aluminum Chloride)**:
- Aluminum has three valence electrons and can accept an electron pair to achieve a stable configuration.
- **Conclusion**: AlCl3 is a Lewis acid.

3. **BaCl2 (Barium Chloride)**:
- Barium is an alkaline earth metal and forms Ba²⁺ ions, while Cl⁻ ions have a complete octet.
- Since both ions have complete octets, BaCl2 does not have the ability to accept an electron pair.
- **Conclusion**: BaCl2 is NOT a Lewis acid.

4. **SnCl4 (Tin(IV) Chloride)**:
- Tin has four valence electrons and can accept an electron pair to complete its octet.
- **Conclusion**: SnCl4 is a Lewis acid.

### Step 3: Final Conclusion
Among the compounds analyzed, **BaCl2** is the compound that is not a Lewis acid because it does not have the ability to accept an electron pair due to the complete octets of its constituent ions.

### Answer:
The compound that is not a Lewis acid is **BaCl2**.

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