Atomic Orbitals vs. Molecular Orbitals [ENDORSED]

[Sristi Palimar 2E]

Can someone distinguish the the difference between electronic transitions in atomic orbitals (atomic spectroscopy) and electronic transitions in molecular orbitals (molecular spectroscopy)?

[Chem_Mod]

The main difference between atomic and molecular orbitals is how we think about the localization of electrons in each case. In atomic orbitals, we view the orbital as the region of electron density of a single atom. So atomic spectroscopy deals with single atom absorbance/emission. In this case all of the electrons density is localized on the one atom. Typically we will only see atomic spectra questions regarding the hydrogen atomic emission spectra. In molecular orbitals, we see the orbital as a region of electron density for the entire complex. We see the orbital as the area where the probability of finding an electron in that whole molecule is highest.The electron density is delocalized over multiple atoms in the molecule.