Ronald S. Roque
BS CHEM 1-B
Practice Exercise
By referring to Figure 2.7, answer the following questions:
1.What group of elements corresponds to the peaks of ionization energy on your graph? Where is
this group located on the periodic table?
He, Ne, Ar, and Kr are the elements that correspond to the ionization energy peaks on the
graph. These elements are classified as noble gases in Group 8a. On the right side of the periodic
table, the noble gases are the last group of elements.
2. What is the trend in the first ionization energies as the atomic number increases within a group
of elements?
The main energy level of atoms increases as the atomic number of a group of elements
increases. As a result, the first ionization energy decreases.
3. What is the trend in the first ionization energies as the atomic number increases across a
period or row of elements?
The valence electron increases as the atomic number increases across a period or row of
elements. As a result, the energy of ionization increases as well.