Question

What is the number of N atoms present in EDTA?

• A. 2
• B. 3
• C. 4
• D. 1

Hint:

The chemical name contains your answer! The fragment "diamine" literally translates to two amine groups, meaning there are exactly 2 nitrogen atoms forming the foundational core of the EDTA molecule.

Answer 1

The Correct Option is A

Step 1: Understanding the Question:
The problem requires determining the exact number of nitrogen ($\mathrm{N}$) atoms contained within a single molecule of the classical chelating ligand EDTA.

Step 2: Key Formula or Approach:
Recall the full systematic IUPAC name and structure of EDTA to map out its constituent elements: EDTA stands for Ethylenediaminetetraacetic acid.

Step 3: Detailed Explanation:
Let's break down the molecule's structure from its name:
1. The central structural backbone is "ethylenediamine", which is a two-carbon chain bonded to two amine groups: $\mathrm{-CH_2-CH_2-}$ linked to two $\mathrm{N}$ atoms.
2. The term "tetraacetic acid" indicates that four acetic acid groups ($-\mathrm{CH_2COOH}$) are substituted onto those nitrogen atoms, replacing their original hydrogen atoms.
The complete chemical structure of EDTA is:
$$\mathrm{(HOOC-CH_2)_2N-CH_2-CH_2-N(CH_2-COOH)_2}$$ Counting the nitrogen atoms explicitly, there are exactly 2 amine-derived nitrogen atoms present in the bridge. These two nitrogens work along with the four carboxyl oxygen atoms to make EDTA a hexadentate ligand.

Step 4: Final Answer:
The number of nitrogen ($\mathrm{N}$) atoms present in EDTA is 2, which corresponds to option (A).