Orbital energy varies based on the nth orbital (ONLY FOR HYDROGEN). As n increases, the level of orbital energy also increases. Based on the level of energy of n, the electrons in an atom can be easily removed, or require more energy to be removed.
Since the size of an orbital is determined by the angular momentum, amount of energy, and magnetic moment, these factors would affect the orbital energy.
**Refer to http://chemwiki.ucdavis.edu/Wikitexts/UCD_Chem_124A%3a_Kauzlarich/ChemWiki_Module_Topics/Electronic_Quantum_Numbers for further information related to quantum numbers.
This is an image of the orbital energy diagram of 1,3 butadiene. From this image, you can see the molecular orbitals, as well as the electron configuration.
Aufbau principle, Pauli Exclusion principle, and Hund's Rule can help you in constructing the Molecular Orbital Diagram. Aufbau's principle states to fill electrons up from the lowest energy orbital to a higher energy orbital. Pauli Exclusion principle states that only two electrons can be filled in a single orbital. Meanwhile, Hund's Rule tells us that only one electron can be filled in orbitals with the same energy level before all individual orbitals in the same energy level are filled with a single electron (usually filled with an up arrow).
This image represents a molecular orbital diagram for B2. This particular structure is used for all atoms below Oxygen. Drawing F2 on a molecular orbital diagram would require another structure of the orbital diagram. See next image.
This image of the molecular orbital diagram describes that of F2. As you can see, the diagram for the 2p orbital differs from that in B2; here, the electrons enter sigma bonding orbital before entering pi bonding orbital. Then it fills up the pi anti bonding orbital before filling in the sigma anti bonding orbital.
The molecular diagram varies between diatomic molecules of H2 through N2 from that of diatomic molecules of O2 through Ne2 comes from the different energies in orbitals. It was calculated that the molecules of O2 through Ne2 have σ 2p orbitals in lower energy than π 2p.
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