This means the electrons have the lowest possible values for n the principal quantum number. When multiple orbitals of the same energy are available the lowest energy state is the one with a single electron in an orbital. Ionization Energy Trends Of The Periodic Table The lowest ionization energy of any element is 389 eV for caesium. . Lithium metal has a first ionization energy work function of 520 Kjmol. Academiaedu is a platform for academics to share research papers. Francium element number 87 at the bottom of the first period has a very low electronegativity while fluorine element number 9 at the top of period 17 has a very high. Electron B feels more effective nuclear charge Zeff than electron A. The ground state is the state in which the electrons in the atom are in their lowest energy levels possible atoms naturally are in the ground state. A H and H 2 b N and N 2 c O and O 2. Allowing for a few ex...