Why is the second ionization energy greater than the first ionization energy in atoms?

1 Answer
Nov 23, 2016


#M(g) + Delta_1 rarr M^(+)(g) +e^-# #"1st ionization energy"#

#M^(+)(g) + Delta_2 rarr M^(2+)(g) +e^-# #"2nd ionization energy"#


Let's look at the process purely on the basis of electrostatics. It should take more energy to remove an electron from a positively charged atom, than from a neutral atom, because the valence electrons of a positive species should be more strongly attracted to the nuclear core, and shielding of the nuclear charge by electrons should diminish.

On this basis alone, #Delta_2>Delta_1#.

In the special case of the alkali metals, the second ionization energy would involve the removal of a non-valence, inner shell electron. And thus, in this instance, #Delta_2# should be PROHIBITIVELY HIGH.....


Are the given data consistent with what we have argued? Why is a second ionization energy not listed for hydrogen?