JEE Advanced · 2013 · 02 Jun 2013 · Paper 1 · Chemical Bonding and Molecular Structure

The total number of lone-pairs of electrons in melamine is

Answer: 6

Solution

Melamine has the structure:

It is a triazine ring (3 N in the ring) with three

- N H_{2}

groups attached.

Each of the 3 ring nitrogen atoms has 1 lone pair
Each of the 3 $- N H_{2}$ groups has 2 nitrogen atoms, but these are bonded and don't have lone pairs in the typical sense; however, each $- N H_{2}$ nitrogen has 1 lone pair

Total: 3 (ring N) + 3 (

- N H_{2}

N) = 6 lone pairs.

JEE Advanced · 2013 · 02 Jun 2013 · Paper 1 · Integer answer