Question

100. Which of the following elements would you expect to have the lowest first ionization energy? a. F d. I b. Br e. Xe c. c1 - --

Answer 1

Ionisation energy "Amount of energy required to remove valance shell electron from the isolated gaseous atom" Atom + le → Atom* + electron lonisation energy a - Atomic size Size decreases (Left to right in periodic table) → Ionisation energy increases Size Increases (top to bottom) – Ionisation energy decreases Periodic variation Left to Right → Ionisation energy increases Top to bottom lonisation energy decreases F> C > Br> 1 (Top to Bottom → Ionisation energy decreases) I<Xe (Left to Right Ionisation energy increases) So, decreasing order of ionisation energy F> d> Br> Xe > Answer (d)