The energy level diagram for an unhybridized oxygen atom illustrates its electronic configuration based on its atomic orbitals. An oxygen atom has eight electrons, with the electron configuration being 1s2 2s2 2p4. In the unhybridized state, the diagram displays the filled 1s and 2s orbitals, and the 2p orbitals holding four electrons. This results in two of the 2p orbitals being half-filled, leading to its bonding characteristics.
For the hybridized (specifically sp3 hybridization) oxygen atom, we typically consider situations like water (H2O). Here, one 2s orbital and three 2p orbitals combine to form four equivalent sp3 hybrid orbitals. This shows a different arrangement in energy levels where the hybrid orbitals are higher in energy than the 2s but lower than the 2p, allowing for a tetrahedral shape with bond angles of approximately 109.5 degrees.
In summary, the unhybridized diagram shows the distinct atomic orbitals, while the hybridized diagram illustrates how the orbitals merge to form new ones that allow for more effective bonding.