Question

I have no idea how to do this: Which ionization of energy of: a. Potassium is prohibitively large? b. Indium is prohibitively large? c. Radium is prohibitively large?

Answer 1

First ionization energy is removal of outermost electron ,

second ionizaton energy is removal of second outermost electron ( where 1st electron is already removed)

a) potassium has electronic onfig of 1s2 2s2 2p6 3s2 3p6 4s1 .

First electron removal gives stable inert gas configuration.   1s2 2s2 2p6 3s2 3p6

Now second electron removal takes lot of energy since we have stable configuration ,

hence potassium has second ionization eenegy very large

b) Indium [Kr] 5s2 5p1 , after 3e- removal we get stable electronic configuration of [Kr]

hence 4th ionization energy ie eenergy required to remove 4th electron is very large

c) Radium has ec of [Rn]7s2 , hence removal of 3rd electron takes larger energy

hence third ionization energy is large