Question

The number of \(\sigma\) bonds and \(\pi\) bonds in \(\mathrm{CO}_{2}\) molecule are \(\quad\) respectively.

Short answer

Answer: In a CO₂ molecule, there are 2 sigma (σ) bonds and 2 pi (π) bonds.

Step-by-step solution

Determine the molecular structure of CO₂

First, we need to figure out the structure of the CO₂ molecule. A CO₂ molecule consists of one carbon atom double bonded to two oxygen atoms (O=C=O).

Identify the sigma (σ) and pi (π) bonds in the molecule

In a double bond, there is always one sigma (σ) bond and one pi (π) bond. As there are two double bonds in CO₂ molecule (each between the carbon and an oxygen atom), we can now calculate the number of sigma (σ) and pi (π) bonds:

Calculate the number of sigma (σ) bonds

Since there is one σ bond in each double bond, CO₂ will have: 1 σ bond (from C=O) + 1 σ bond (from C=O) = 2 σ bonds

Calculate the number of pi (π) bonds

As there is one π bond in each double bond, CO₂ will have: 1 π bond (from C=O) + 1 π bond (from C=O) = 2 π bonds In conclusion, the number of sigma (σ) bonds and pi (π) bonds in a CO₂ molecule are 2 and 2, respectively.

Key concepts

Sigma Bonds

Sigma bonds (\(\sigma\) bonds) are the strongest type of covalent chemical bond. These bonds are formed by the "head-on" overlapping of atomic orbitals.

When we look at molecules such as \(\mathrm{CO}_{2}\), understanding sigma bonds gives us a window into the stability and structural integrity of the molecule. They are foundational to the molecule's strength.

• Formation: A sigma bond can form between two s orbitals, or an s and a p orbital, or even two p orbitals aligned properly, stretching directly between two nuclei.
• Characteristics: Sigma bonds allow for free rotation of bonded atoms. This is because the electron cloud in sigma bonds is symmetrically distributed along the axis connecting the two nuclei.

In a \(\mathrm{CO}_{2}\) molecule, each oxygen is double-bonded to the central carbon. So, each C=O bond contains one sigma bond. Therefore, \(\mathrm{CO}_{2}\) has 2 sigma bonds in total.

Pi Bonds

Pi bonds (\(\pi\) bonds) are a form of covalent chemical bond where the "sideways" overlapping of atomic orbitals creates bonding above and below the plane of the atoms involved. They often exist in conjunction with sigma bonds, adding complexity and rigidity to molecular structures.

In double bonds like those in \(\mathrm{CO}_{2}\), pi bonds are crucial to maintaining the molecule's planar structure.

• Formation: Pi bonds occur when parallel p orbitals overlap, allowing electrons to be shared across the bond in two lobes (above and below the plane).
• Characteristics: Pi bonds prevent the rotation of the bonded atoms. One pi bond, occurring in addition to a sigma bond in double bonds, adds to the rigidity of the molecule.

In our example molecule \(\mathrm{CO}_{2}\), each carbon to oxygen connection forms one pi bond on top of the sigma bond, totaling 2 pi bonds in the molecule's structure.

Molecular Structure

The molecular structure of a molecule such as \(\mathrm{CO}_{2}\) is a combination of its spatial arrangement of atoms and the type of chemical bonds that hold these atoms.

Understanding molecular structure is critical to predicting a molecule's reactivity, polarity, phase of matter, color, magnetism, biological activity, and other properties.

• Linear Structure: In \(\mathrm{CO}_{2}\), the molecule is linear. The central carbon atom forms double bonds with each oxygen atom, leading to a straight-line configuration — denoted as O=C=O.
• Bond Angles: In a linear molecule like \(\mathrm{CO}_{2}\), the angle between the bonds is 180°.
• Nonpolar Nature: Due to its linear shape and even distribution of charge, \(\mathrm{CO}_{2}\) is a nonpolar molecule. The dipole moments cancel out, resulting in zero net dipole moment.

This blend of geometry and bond type dictates not only the molecular shape but also informs us about how this molecule will interact with others.