What is the Meaning of the Fermi Energy?

[chikchok]

TL;DR Summary

Is fermi energy is the energy of one of the two electrons located in the state n=1?

The Fermi energy Ef is defined as the energy of the topmost filled level in the ground state of the N electron system. Ground state is n=1 level. And in the ground state there can be only one orbital right? One orbital can have only up to 2 electrons. Does this mean that fermy energy is the energy of one of the two electrons located in this orbital (in n=1 state)?

 

[Dale]

The ground state is only n=1 for hydrogen and helium