Ionization Energies. Alkali metals have the lowest ionization energy in each period and this is due to their having the largest atomic size in their respective periods. . ... The valence electrons in large sized atoms are held loosely by the nucleus and can be lost easily. read more
Ionization energy is the energy required to remove an electron from an atom or ion. Low ionization energy indicates that it takes less energy to remove an electron from the atom. The alkali metals are in Group I on the Periodic Table. This indicates that their atoms have only one electron (out of a possible eight) in their outermost energy level. read more