Ionization energy, what's needed to remove 1 electron from 1 atom, is high for this non-reactive 6-element group
[DOC] [TLE] Ionization energy trends - Khan Academy [PAR] Dec 22, 2014 - 10 minDefinition of ion and ionization energy, and trends in ionization energy across a  period and ... [DOC] [TLE] Period 3 element - Wikipedia [PAR] A period 3 element is one of the chemical elements in the third row (or period) of 
the periodic ... As the atomic number of elements in Period 3 increases, the 
atomic radius ... the amount of energy required to remove its electrons (Ionization 
energy) ...