Which of the following molecules acts as a Lewis acid?

Options

A. (a) `(CH_(3))_(3)B`
B. (b) `(CH_(3))_(2)O`
C. (c) `(CH_(3))_(3)P`
D. (d) `(CH_(3))_(3)N`

Explanation

To determine which of the given molecules acts as a Lewis acid, we need to identify which molecule is electron deficient and can accept a pair of electrons. Here’s the step-by-step solution:

### Step 1: Understand the Definition of Lewis Acid
A Lewis acid is defined as a species that can accept a pair of electrons from a donor atom. This means that Lewis acids are typically electron deficient.

### Step 2: Analyze Each Option
We have four options to analyze:
1. **Option A: CH3 thrice B (Boron)**
2. **Option B: CH3 twice O (Oxygen)**
3. **Option C: CH3 thrice P (Phosphorus)**
4. **Option D: CH3 thrice N (Nitrogen)**

### Step 3: Evaluate Option A (CH3 thrice B)
- **Central Atom**: Boron (B)
- **Atomic Number**: 5
- **Electron Configuration**: 1s² 2s² 2p¹
- **Bonding**: Boron forms three covalent bonds with three CH3 groups.
- **Electron Count**: After bonding, Boron has 6 electrons in its valence shell but has one vacant 2p orbital.
- **Conclusion**: Boron is electron deficient and can accept a pair of electrons, making it a Lewis acid.

### Step 4: Evaluate Option B (CH3 twice O)
- **Central Atom**: Oxygen (O)
- **Atomic Number**: 8
- **Electron Configuration**: 1s² 2s² 2p⁴
- **Bonding**: Oxygen forms two bonds with two CH3 groups and has two lone pairs.
- **Electron Count**: The octet of oxygen is complete (8 electrons).
- **Conclusion**: Oxygen is not electron deficient and does not act as a Lewis acid.

### Step 5: Evaluate Option C (CH3 thrice P)
- **Central Atom**: Phosphorus (P)
- **Atomic Number**: 15
- **Electron Configuration**: 1s² 2s² 2p⁶ 3s² 3p³
- **Bonding**: Phosphorus forms three bonds with three CH3 groups and has one lone pair.
- **Electron Count**: The octet of phosphorus is complete.
- **Conclusion**: Phosphorus is not electron deficient and does not act as a Lewis acid.

### Step 6: Evaluate Option D (CH3 thrice N)
- **Central Atom**: Nitrogen (N)
- **Atomic Number**: 7
- **Electron Configuration**: 1s² 2s² 2p³
- **Bonding**: Nitrogen forms three bonds with three CH3 groups and has one lone pair.
- **Electron Count**: The octet of nitrogen is complete.
- **Conclusion**: Nitrogen is not electron deficient and does not act as a Lewis acid.

### Final Conclusion
After analyzing all options, the only molecule that acts as a Lewis acid is **Option A: CH3 thrice B**.

### Summary of the Answer
**The molecule that acts as a Lewis acid is CH3 thrice B (Boron).**

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