Which of the following statements is not correct for a nucleophile ?

Options

A. Nucleophilies attack low e- density sites
B. Nucleophiles are electron donating
C. Nucleophiles is a Lewis acid
D. Ammonia is a nucleophile

Explanation

To determine which statement is not correct for a nucleophile, we can analyze the properties and definitions associated with nucleophiles. Here’s a step-by-step solution:

### Step 1: Understand the Definition of Nucleophiles
A nucleophile is defined as an electron-rich species that has a tendency to donate an electron pair to an electron-deficient site (often a positively charged atom). Nucleophiles can be negatively charged ions or neutral molecules with lone pairs of electrons.

**Hint:** Remember that nucleophiles are characterized by their electron-rich nature.

### Step 2: Analyze the Statements
We need to evaluate each statement provided in the options to identify which one is incorrect.

1. **Statement 1:** Nucleophiles attack low electron density sites.
- This statement is correct because nucleophiles are attracted to areas of low electron density where they can donate their electrons.

2. **Statement 2:** Nucleophiles are electron donating.
- This statement is also correct. Nucleophiles donate electrons to electron-deficient sites during chemical reactions.

3. **Statement 3:** Nucleophile is a Lewis acid.
- This statement is incorrect. A Lewis acid is defined as an electron pair acceptor, which is the opposite of a nucleophile. Nucleophiles are electron pair donors, not acceptors.

4. **Statement 4:** Ammonia is a nucleophile.
- This statement is correct. Ammonia (NH₃) has a lone pair of electrons on the nitrogen atom, making it a nucleophile.

### Step 3: Identify the Incorrect Statement
From the analysis, we can conclude that the incorrect statement is:
- **Statement 3:** Nucleophile is a Lewis acid.

### Final Answer
The statement that is not correct for a nucleophile is: **Nucleophile is a Lewis acid.**