find the total number of compounds whose bond is uneffected weather the s-p mixing is considered or not B2 , C2 , N2 , O2

To determine the total number of compounds whose bonding is unaffected by s-p mixing, we need to analyze the molecular orbital (MO) theory for the diatomic molecules B2, C2, N2, and O2. The concept of s-p mixing refers to the interaction between the s and p atomic orbitals when forming molecular orbitals, which can influence the energy levels and the arrangement of electrons in these molecules.

Understanding Molecular Orbitals

Molecular orbital theory provides a framework for understanding how atomic orbitals combine to form molecular orbitals. In diatomic molecules, the energy levels of the atomic orbitals can vary based on the atomic number and the types of orbitals involved. The key point here is that s-p mixing can occur in lighter elements, affecting the order of the molecular orbitals.

Analyzing Each Molecule

• B2 (Boron Dimer): In B2, s-p mixing occurs, leading to the formation of lower-energy bonding orbitals. The molecular orbital configuration is (σ1s)²(σ*1s)²(σ2s)²(σ*2s)²(π2p)². The presence of s-p mixing is significant here, as it stabilizes the π2p orbitals.
• C2 (Carbon Dimer): For C2, s-p mixing is also relevant. The molecular orbital configuration is (σ1s)²(σ*1s)²(σ2s)²(σ*2s)²(π2p)⁴. The mixing affects the energy levels of the π orbitals, making them lower in energy compared to the σ2p orbitals.
• N2 (Nitrogen Dimer): In N2, s-p mixing is not significant. The molecular orbital configuration is (σ1s)²(σ*1s)²(σ2s)²(σ*2s)²(σ2p)²(π2p)⁴. Here, the σ2p orbital is lower in energy than the π2p orbitals, indicating that the bonding is not influenced by s-p mixing.
• O2 (Oxygen Dimer): For O2, s-p mixing does occur, but it has a different impact. The molecular orbital configuration is (σ1s)²(σ*1s)²(σ2s)²(σ*2s)²(σ2p)²(π2p)⁴(π*2p)². The presence of unpaired electrons in the π* orbitals indicates that the molecule is paramagnetic, and the mixing affects the energy levels of the orbitals.

Identifying the Compounds Unaffected by s-p Mixing

From our analysis, we can summarize the findings:

• B2: Affected by s-p mixing
• C2: Affected by s-p mixing
• N2: Not affected by s-p mixing
• O2: Affected by s-p mixing

Final Count

Only N2 is unaffected by s-p mixing. Therefore, the total number of compounds among B2, C2, N2, and O2 whose bonding is not influenced by s-p mixing is:

1 compound (N2)

This analysis highlights how the molecular orbital configurations and the presence or absence of s-p mixing can significantly influence the bonding characteristics of diatomic molecules. Understanding these concepts is crucial for predicting the properties and behaviors of different compounds in chemistry.