Establish the trend in ionization energy and determine the positions of the elements in the periodic table to find out which has the largest first IE
Ionization energy is the energy required to remove an electron from a gaseous atom or ion.
The trend of the ionization energies of the elements can be observed in the periodic table:
•increases going from left to right of a period
Which of the following elements has the largest first ionization energy?
A. Rb B. Mg C. Na D. Cl E. Br