# Ionization energy - compare 2 unknown elements and decide their group

 P: 14 Hello. I have a question about ionization energy: Two hypothetical elements in the 2nd or 3rd period have the following ionization energies: Element X First: 800 kJ/mol Second: 2500 kJ/mol Third: 3900 kJ/mol Fourth: 23000 kJ/mol Element Y First: 700 kJ/mol Second: 2200 kJ/mol Third: 3500 kJ/mol Fourth: 19000 kJ/mol To what group in the periodic table should element X be in, and what charge should the ion in element X have? The answer is group 13 and charge +3. How could you possibly know this? I can see that the fourth energy level is far more than the third, so it should be somewhere between group 13-17, but how do you know which one?
 Admin P: 23,599 Why is the fourth much larger? What does it tell you about electrons being removed?
P: 14
 Quote by Borek Why is the fourth much larger? What does it tell you about electrons being removed?
Well, is it because the first three energy levels remove all the group 13 valence electrons, and then you need much more energy to remove one more electron? But wouldn't it require much energy to remove the last valence electron in any element, so why can't it be for example group 14 loosing 4 valence electrons?

 Admin P: 23,599 Ionization energy - compare 2 unknown elements and decide their group How many valence electrons in group 14?
 P: 14 4. Which tells me.. ?
 Admin P: 23,599 What is a difference between valence electrons and other electrons? Which are easier, which are harder to remove?
 P: 14 I'm sorry, but this leads me nowhere, so I'll be better off if someone simply could give me an explanation of why it is group 13.
 Admin P: 23,599 Don't give up so easily. Try to answer the questions I asked. You DO know what are valence electrons? What definition do you know? Why are they called "valence"?
 P: 14 Yes, I know what valence electrons are; the electrons in an atoms outer shell. Group 13 elements have 3 valence electrons. Then I figure that in the first, second and third ionization energy levels you have removed 1, 2 and 3 of the group 13 valence electrons, so that there are no valence electrons left. In the fourth level, you are removing an additional electron. Is it this "jump" from the outer shell to the inner that requires much more energy?