Question

Which of these has the largest second IE (IE2)?

K
Al
Rb
Sr
Ca

How do you solve this?

Answer 1

are you trying to find the Ionization Energy? If so the trend goes up and right.

Answer 2

Its asking for IE2, however.

Answer 3

Ionization energy 2

Answer 4

The second Ionization energy (the energy required to pull two electrons away) increases the further right and up on the periodic table you go (as stated above)- pretty much going towards the Florine. However, it's not exactly a linear process- It has a weird zigzag line where some elements are higher or lower depending on their position on the periodic table.

SO it's realitvely easier to remove an electron from a partially filled valence shell because the Zeff (effective nuclear charger) is lower, but its hard to remove an eletron from a filled valence shell because the Zeff is higher. Ions formed by reaction of main-group elements usually have filled s and p subshells, which corresponds to having 8 electrons (octet). so Na loses one electron easily , magnesium loses 2 electron easily, aluminum loses 3 easily, and so on. That's why its hard to guess which element has the highest IE, but to give an educated guess, I would say the Rb since it has such a large atomic radii. but again, I'm not a 100% sure. I would def check an ionzation chart from your book.

Answer 5

It would be K. Imagine if you have already taken one electron from K. It would have a noble gas config. If you want to pull a second electron from it you would have to invest a large large large amount of energy into it.

Answer 6

K has the largest 2nd IE of the elements listed, for the reasons @FlyersMania14 mentioned