Orbital Diagrams of Atoms Hunds Rule

These orbital diagrams show different states of the carbon atom. Each state has a different energy and, as you will see, different magnetic characteristics. 

The next two electrons go into separate 2p orbitals, with both electrons having the same spin, following Hund s rule. 

We see that the orbital diagram corresponding to the lowest energy is the one we previously labeled Diagram 1. 

To apply Hund s rule to the oxygen atom, whose ground-state configuration is ls 2s 2p , we place the first seven electrons as follows  

The last electron is paired with one of the 2p electrons to give a doubly occupied orbital. The orbital diagram for the ground state of the oxygen atom is 

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