# What is the element with the greatest first ionization energy?

Identify the element with the greatest first ionization energy.
(A) Ce
(B) C
(C) Cl
(D) Ca
(E) Cs

The book says the correct answer is (B) with such an explanation:

First ionization energy is a periodic trend that increases up and to the right on the periodic table. After looking at the position of these elements on the periodic table, carbon is clearly the best answer-choice (B).

However, a chart I found on Google Images (Ionization Energy Chart) says that Cl has the greatest first ionization energy. What is right then?

• my special chart and web sites - please edit your post to cite your sources for this data – NotEvans. Aug 22 '17 at 13:44
• Find better textbook... – Mithoron Aug 22 '17 at 16:57