"Ionization Energy" is the energy difference between an electron at rest at infinity and an electron at a certain energy level. The amount of energy required to remove an electron from that atom or molecule in the gas phase.
Applicable units are those of quantitykind:Energy
http://en.wikipedia.org/wiki/Ionization_energy
"Ionization Energy" is the energy difference between an electron at rest at infinity and an electron at a certain energy level. The amount of energy required to remove an electron from that atom or molecule in the gas phase.
http://www.iso.org/iso/catalogue_detail?csnumber=31897