In Molecular Orbital Theory, while explaining MO diagram of Nitrogen (N2) molecule, why the AO levels are different from AO levels of O2?
In Molecular Orbital (MO) theory, the molecular orbital diagram of a molecule is constructed by combining the atomic orbitals (AOs) of the constituent atoms. The energy levels of the AOs can vary depending on the specific atom and its electron configuration.
In the case of Nitrogen (N2) and Oxygen (O2) molecules, the AO levels are different because their constituent atoms have different electron configurations and atomic properties.
Nitrogen (N) has an atomic number of 7, with its ground state electronic configuration as 1s^2 2s^2 2p^3. When two nitrogen atoms come together to form a N2 molecule, each nitrogen atom contributes three half-filled p orbitals (2px, 2py, and 2pz). These three half-filled p orbitals of each nitrogen atom can overlap and form three molecular orbitals: sigma (σ), pi (π), and the second pi (π*) orbitals.
On the other hand, Oxygen (O) has an atomic number of 8, with its ground state electronic configuration as 1s^2 2s^2 2p^4. When two oxygen atoms come together to form an O2 molecule, each oxygen atom contributes two half-filled p orbitals (2px and 2py) and one π* orbital. The resulting molecular orbital diagram of O2 will have two sigma (σ) orbitals, two pi (π) orbitals, and two pi star (π*) orbitals.
Therefore, the AO levels in the MO diagram of N2 are different from O2 due to the variation in the number and arrangement of the atomic orbitals of nitrogen and oxygen atoms.
To obtain the molecular orbital diagram, one can use the following steps:
1. Write down the electron configuration of the individual atoms.
2. Determine the number and type of atomic orbitals contributed by each atom.
3. Determine which atomic orbitals overlap and combine to form molecular orbitals.
4. Assign electrons to the molecular orbitals following the filling order, considering the Pauli exclusion principle and Hund's rule.
5. Fill the molecular orbitals with the available electrons, indicating their spins (up or down).
By following these steps, the appropriate MO diagram can be constructed, providing insights into the bonding and electronic properties of the molecule.