Question

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

Short answer

There are no ionic or coordinate bonds in HNO2.

Step-by-step solution

Analyze the Structure of HNO2

The chemical formula \( \mathrm{HNO}_2 \) represents nitrous acid. Let's start by examining its structure: \( \mathrm{HNO}_2 \) can be drawn as H-O-N=O, with two resonance structures. There is an O-H bond, an N=O double bond, and an N-O single bond.

Identify the Types of Bonds

In \( \mathrm{HNO}_2 \), we find different types of bonds. An O-H bond (covalent), an N-O single bond (covalent), and an N=O double bond (covalent). There are no metal or non-metal ions to form ionic bonds, nor are there any coordinate bonds since each atom uses its own electrons to form bonds.

Determine the Bond Types Not Present

Based on our identification, \( \mathrm{HNO}_2 \) only contains covalent bonds (standard and double) but no coordinate covalent bonds (where one atom donates both electrons for bonding) and no ionic bonds (transfer of electrons).

Key concepts

Covalent Bonds

Covalent bonds are a fundamental type of chemical bond where atoms share pairs of electrons. This sharing allows each atom to attain a stable electron configuration, resembling that of noble gases. In the nitrous acid molecule, \( \mathrm{HNO}_2 \), covalent bonds are prevalent.

Key examples in \( \mathrm{HNO}_2 \) include:

• O-H bond: A single covalent bond formed between hydrogen and oxygen, involving shared electrons.
• N-O bonds: Both a single and a double bond are present. In these bonds, each nitrogen and oxygen atom shares electrons, making them covalent.

Unlike other bond types, covalent bonds in \( \mathrm{HNO}_2 \) do not involve any ions, making them distinctly different from ionic bonds.

Resonance Structures

Resonance structures are different ways of drawing the same molecule, showing different possible arrangements of electrons. They are crucial for illustrating how molecules like \( \mathrm{HNO}_2 \) behave.

In \( \mathrm{HNO}_2 \), there are two primary resonance structures. They demonstrate different placements of the electrons between the nitrogen and oxygen atoms. These structures do not imply that the molecule flips between forms but instead that the true structure is a blend of these possibilities. Therefore, resonance contributes to the stability of the molecule by allowing for electron delocalization over the participating atoms, particularly in the N=O bond.

Bond Identification

Bond identification is about recognizing the type of bond present in a molecule. In chemistry, knowing which bonds exist informs us about the molecule's properties and reactivity.

For \( \mathrm{HNO}_2 \), it's important to identify:

• Covalent bonds: Present as O-H, N=O, and N-O, where electrons are shared between atoms.
• Absence of Ionic Bonds: Since no electrons are transferred, ionic bonds are not present.
• Absence of Coordinate Covalent Bonds: All atoms in \( \mathrm{HNO}_2 \) use their own electrons to form bonds, thus no coordinate bonds exist.

Understanding these bond types is crucial for predicting molecular interactions and behavior.

HNO2 Structure

The structure of \( \mathrm{HNO}_2 \), also known as nitrous acid, is central to understanding its chemical properties. It involves an arrangement of hydrogen, nitrogen, and oxygen atoms.

The typical structural representation is \( \text{H-O-N=O} \), indicating:

• O-H bond: A single covalent bond between oxygen and hydrogen.
• N=O bond: A double covalent bond showing a robust interaction between nitrogen and an oxygen atom.
• N-O bond: A single covalent bond connecting nitrogen to another oxygen atom.

This arrangement is essential for explaining the absence of both ionic and coordinate covalent bonds in \( \mathrm{HNO}_2 \), as every atom contributes its own electrons for bonding, and there is no electron transfer characteristic of ionic bonding.