Problem 55 - A Complete Resource Book in Chemistry for JEE Main

Question

Number of electrons shared in the formation of nitrogen molecule is (a) 10 (b) 8 (c) 6 (d) 2

Step-by-Step Solution

Answer

6 electrons are shared in a nitrogen molecule.

Step 1: Understanding Nitrogen Molecule Formation

Nitrogen molecules are formed by two nitrogen atoms. Each nitrogen atom has 5 electrons in its outer shell and needs 3 more electrons to complete its octet.

Step 2: Lewis Structure of Nitrogen

To complete their octets, each nitrogen atom shares three of its electrons with the other nitrogen atom. This results in a triple bond between the nitrogen atoms.

Step 3: Calculating Shared Electrons

In a triple bond, a total of 6 electrons are shared between the two nitrogen atoms. Each bond consists of 2 electrons, hence for a triple bond: 3 bonds  2 electrons per bond = 6 electrons.

Key Concepts

Lewis Structure

The Lewis Structure is a simple diagram that represents the valence electrons of atoms within a molecule. It is a helpful tool for visualizing how atoms share electrons to form bonds and fulfill the octet rule. In the case of the nitrogen molecule (\(N_2\)), we begin by considering the valence electrons, which are the electrons found in the outer shell of an atom. Each nitrogen atom has 5 valence electrons. To easily grasp this concept, imagine electrons as dots placed around the chemical symbol of an element.

• These dots represent each valence electron available for bonding.
• In the nitrogen molecule, both N atoms hope to achieve a stable electronic arrangement by having 8 electrons in their valence shell.

Through the Lewis Structure, we visually observe how nitrogen achieves stability. Nitrogen atoms each share three electrons to satisfy the octet rule, forming a robust triple bond depicted as three parallel lines between the N symbols.

Triple Bond

A triple bond, found in molecules like nitrogen (\(N_2\)), is one of the strongest types of chemical bonds. It forms when two atoms share three pairs of electrons, meaning 6 electrons in total are involved in this connection. The nature of the triple bond endows it with distinct properties.

• The triple bond is represented by three lines between the bonded atoms in a Lewis Structure.
• Each line corresponds to a pair of shared electrons.
• A triple bond is very strong and requires significant energy to break.

In molecules like nitrogen, the presence of a triple bond is crucial for achieving stability and low energy state, which makes the molecule less reactive. Known for its strength and rigidity, the triple bond is pivotal in defining the physical and chemical characteristics of nitrogen gas, which is plentiful in Earth's atmosphere.

Octet Rule

The octet rule is a chemical rule that describes how atoms tend to bond in ways that allow them to have eight electrons in their valence shell. This rule is based on the principle that, in chemistry, atoms are more stable when they possess a full outer shell similar to the configuration of noble gases. Let's delve into how the octet rule applies to nitrogen (\(N_2\)).

• For nitrogen atoms, which have 5 valence electrons, achieving 8 requires sharing electrons.
• This is accomplished by each nitrogen atom forming three bonds with another nitrogen atom.
• The sharing of 3 pairs of electrons allows each atom to "pretend" they have 8 electrons.

The octet rule underscores the stability found in molecular structures like \(N_2\), where both atoms attain a stable electronic configuration. Understanding this rule helps explain why certain molecules form and behave the way they do, especially in the realm of covalent bonding.