Problem 119 - A Complete Resource Book in Chemistry for JEE Main

Question

Which type of bond is not present in HNO \(_{2}\) molecule? (a) covalent (b) coordinate (c) ionic (d) ionic as well as coordinate

Step-by-Step Solution

Answer

No ionic bond is present in HNO e; only covalent and possibly coordinate bonds are present.

Step 1: Understanding the Molecule Structure

First, understand the structure of the HNO e molecule. It consists of one hydrogen atom (H), one nitrogen atom (N), and two oxygen atoms (O). Typically, the bonding structure involves the nitrogen atom bonded to the hydrogen atom and the two oxygen atoms.

Step 2: Identifying Types of Bonds

Analyze the common bonds: covalent bonds occur when atoms share electron pairs, while coordinate bonds involve one atom providing a pair of electrons for a bond (often between nitrogen and an oxygen with an unshared electron pair). Ionic bonds, requiring electron transfer, are unlikely due to the absence of metals and nonmetals.

Step 3: Evaluate Ionic Bond Presence

In HNO e, electrons are shared between nonmetals. There is no transfer of electrons typical of ionic bonds, ruling out the presence of ionic bonds. Evaluate using the atomic constituents; the presence of only nonmetals suggests ionic bonds are absent.

Step 4: Consider Coordinate Bond Possibility

Identify coordinate bonds by examining if there is a bond formed with a shared pair of electrons provided by one atom. This is common in polyatomic ions involving nitrogen and oxygen, where a coordinate bond is likely present.

Step 5: Conclusion on Bond Types

Since HNO e contains covalent bonds between hydrogen, nitrogen, and oxygen atoms, and the possibility of a coordinate bond, but no elements typical for ionic bonding, the molecule lacks ionic bond presence.

Key Concepts

Covalent Bonds

Covalent bonds form when two atoms share one or more pairs of electrons. This bond typically occurs between nonmetal atoms. In a molecule like HNO two, we see covalent bonds holding the structure together. For example:

• A nitrogen atom shares electrons with oxygen atoms.
• The hydrogen atom forms a covalent bond with the nitrogen atom.

This sharing allows each atom to attain a stable electronic configuration, similar to noble gases.
Covalent bonds can vary in strength and length but generally provide the stability necessary for molecule formation.
Since HNO two is composed solely of nonmetals, covalent bonding is a significant contributor to its molecular structure.

Coordinate Bonds

Coordinate bonds are a special type of covalent bond. Here, both the shared electrons come from the same atom. This is often seen in complex molecules or ions.

• In compounds like HNO two, the nitrogen atom can form a coordinate bond with an oxygen atom.
• This happens typically when one atom like nitrogen has a lone pair.

This lone pair is donated to bind with another atom that requires electrons to achieve stability.
Coordinate bonds introduce unique properties to molecules, such as forming polyatomic ions, which are essential in chemistry for compound reactivity and interaction.
Recognizing coordinate bonds requires looking for lone pairs and potential electron acceptors within the molecule.

Ionic Bonds

Unlike covalent and coordinate bonds, ionic bonds occur when electrons are completely transferred from one atom to another. This transfer typically happens between metals and nonmetals.

• Metals often lose electrons to become positive ions.
• Nonmetals gain these electrons to become negative ions.

The resulting attraction between the oppositely charged ions forms a strong bond.
However, in the molecule like HNO two, all participating atoms are nonmetals.
Therefore, ionic bonds do not form as there is no transfer of electrons, only sharing, in this structure. Understanding the absence of ionic bonds in nonmetal-only compounds highlights the importance of electronegativity in bond formation.