Question

What is the number of sigma and pi bonds present in a molecule of sulphuric acid? (a) \(6 \sigma, 2 \pi\) (b) \(6 \sigma, 0 \pi\) (c) \(2 \sigma, 4 \pi\) (d) \(2 \sigma, 2 \pi\)

Short answer

(a) 6 c, 2 c

Step-by-step solution

Understanding the Structure of Sulphuric Acid

Sulphuric acid has the chemical formula H₂SO₄. Its structure includes a sulfur atom bonded to four oxygen atoms, with two of these oxygen atoms forming double bonds with sulfur.

Identifying Sigma Bonds

Sigma bonds (c) are single covalent bonds, and they can also form part of double bonds. In the structure of H₂SO₄, there are two c bonds between the hydrogen atoms and the oxygen atoms, two c bonds between the sulfur atom and the double-bonded oxygen atoms, and two more c bonds between the sulfur and the two single-bonded oxygen atoms. So, there are a total of six sigma bonds.

Identifying Pi Bonds

Pi bonds (c) are the second bonds in a double bond, following a sigma bond. In H₂SO₄, the oxygen atoms forming double bonds with the sulfur account for the presence of two c bonds, one in each of the two double bonds.

Key concepts

Understanding Sigma Bonds

Sigma bonds, denoted as \(\sigma\) bonds, are a fundamental component of chemical structures providing strength and stability. They form by the head-on overlap of atomic orbitals, which leads to the formation of a strong covalent bond. In the case of sulphuric acid \((\text{H}_2\text{SO}_4)\), sigma bonds play a crucial role.
The molecule features:

• Two sigma bonds between hydrogen atoms and oxygen atoms
• Two sigma bonds in the double bonds between the sulfur atom and the oxygen atoms
• Two sigma bonds between the sulfur and the remaining single-bonded oxygen atoms

This summation leads to a total of six sigma bonds in sulphuric acid. Sigma bonds are integral as they form the skeleton of many molecules, including H₂SO₄.

Unpacking Pi Bonds

Pi bonds, notated as \(\pi\) bonds, complement sigma bonds in molecules that have double or triple bonds. Unlike sigma bonds, pi bonds result from the lateral overlap of p-orbitals. They are typically weaker than sigma bonds but necessary for the formation of multiple bonds.
In sulphuric acid, each double bond between sulfur and an oxygen atom consists of one sigma bond and one pi bond:

• Two pi bonds associated with the two double bonds in sulphuric acid

These two pi bonds are responsible for the molecule's ability to engage in resonance, which stabilizes the molecule overall. Understanding pi bonds is key in recognizing the full scope of chemical interactions within and between molecules.

Chemical Bonding in Molecules

Chemical bonding is the glue holding atoms together in molecules, dictated by electron interactions. These bonds can be categorized into several types, with covalent bonds, such as sigma and pi bonds, being most relevant in organic and inorganic chemistry.
In the context of sulphuric acid, chemical bonding involves:

• Formation of covalent sigma bonds through direct orbital overlap, mostly contributing to molecular framework integrity
• Formation of pi bonds through side-by-side orbital overlap, essential for double bonding and molecular rigidity

These interactions determine the chemical properties, reactivity, and stability of the molecules.

Significance in NEET Chemistry

For students preparing for exams like NEET Chemistry, understanding the intricacies of chemical bonds is vital. Topics such as sigma and pi bonds, and their role in molecules, are cornerstones of the chemistry curriculum.
Inclining knowledge toward:

• How different types of chemical bonding affect molecular geometry
• Impacts of bonding on molecular properties and reactivity
• The ability to analyze molecular structures and predict chemical behavior

These insights not only equip students with the skills necessary for exams but also for practical applications in chemistry and related fields. Solidifying these concepts can greatly enhance problem-solving abilities critical in competitive examinations.