Ionization energy: 19th: s- and p-block
The 19th ionization energy of the element M is a measure of the energy required to remove one electron from one mole of the gaseous ion M18+
- J.E. Huheey, E.A. Keiter, and R.L. Keiter in Inorganic Chemistry : Principles of Structure and Reactivity, 4th edition, HarperCollins, New York, USA, 1993.D.R. Lide, (Ed.) in Chemical Rubber Company handbook of chemistry and physics, CRC Press, Boca Raton, Florida, USA, 79th edition, 1998.