Choose the element with the higher ionization energy from each pair. a. Mg or P b. As or Sb c. N or Si

Question

Choose the element with the higher ionization energy from each pair.

a. Mg or P

b. As or Sb

c. N or Si

Answer 1

Ionization energy is the amount of energy required to pull an electron away from the attractive electric force of the nucleus.

Let's think! Will ionization be higher or lower on the right side of the periodic table? Compare the energy required to take an electron away from a very happy noble gas, compared to an element like Potassium. This will help you understand the (general) periodic trend for Ionization energy- it increases from left to right. It also increases going UP a group (for instance, Li has a higher Ionization energy than Cs) because of the atomic size! So in general the periodic trend is that Ionization energy INCREASES across a period and DECREASES DOWN a group

It also takes more energy to take an electron from a filled orbital or a half filled orbital (which are unusually stable). For instance, since Nitrogen is a half-filled orbital, it actually has a slightly LOWED ionization energy than oxygen, despite the periodic trend.

 

a) Since they are in the same period, which element is closer to the right side of the periodic table? The electron on the right side of the periodic table has a harder time pulling away that electron! (I'll give you the answer to this one but not the other two- its P!)

b) Since the are in the same group which one is higher up on the periodic table? The one that is higher up means that is it smaller, meaning that is takes more energy to pull away the electron from the nucleus

c) If you understand the first two this one should be easy! One is both higher and more to the right!

 

Hope that helps, if you still have some difficulties with the concepts, go check out khan academy's videos on the subject! :)