Topic 7: Periodic Trends, Video C: Ionization Energy Part 1

Question 1

What is ionization energy?

Answer 1

The energy required to remove an electron from an atom in the gas phase to create a positive ion.

Question 2

The successive ionization energies for an unknown element are: I₁=896 kJ/mol, I₂=1752 kJ/mol, I₃=14807 kJ/mol and I₄=17948 kJ/mol. To which group in the periodic table does this element belong? (Hint: How many valence electrons does this element have?)

Answer 2

There is a large jump in ionization energy from I_2, and I₃ which means the 3rd electron is more difficult to remove than the second. The third and fourth ionization energies are much higher than the first and second ionization energies. This atom has two electrons that are easy to remove. These must be in the outershell. This element has two valence electrons. This element must be from Group 2.

Question 3

Are core electrons more difficult to remove from an atom than valence electrons? Why or why not?

Answer 3

Yes, because they are more tightly bound to the nucleus.

Question 4

Why do the orbital energies drop when you lose an electron from an ion?

Answer 4

Because you have one less electron and therefore fewer electron electron repulsions and so the orbital energies get a little more attractive which are lower in energy.