Rank the following elements in order of increasing ionization energy:Br, F, Ga, K and Se.

• A. Ga < K < Br < Se < F
• B. Ga < Br < K < Se < F
• C. K < Se < Ga < Br < F
• D. K < Ga < Se < Br < F
• E. K < Ga < Se < F < Br

Answer: (D)

Verified step by step guidance

1. Understand the concept of ionization energy: Ionization energy is the energy required to remove an electron from an atom in the gaseous state. It generally increases across a period (left to right) and decreases down a group (top to bottom) in the periodic table.
2. Identify the position of each element in the periodic table: K (Potassium) is in Group 1, Ga (Gallium) is in Group 13, Se (Selenium) is in Group 16, Br (Bromine) is in Group 17, and F (Fluorine) is also in Group 17.
3. Apply the periodic trend: Since ionization energy increases across a period, elements further to the right in the same period will have higher ionization energies. Therefore, F will have a higher ionization energy than Br, and Br will have a higher ionization energy than Se.
4. Consider the group trend: Ionization energy decreases down a group, so K, being in Group 1, will have the lowest ionization energy. Ga, being in Group 13, will have a higher ionization energy than K but lower than Se, Br, and F.
5. Rank the elements based on the trends: Start with the element with the lowest ionization energy (K), followed by Ga, then Se, Br, and finally F, which has the highest ionization energy. The correct order is K < Ga < Se < Br < F.