Question

consider four elements from group 17: fluorine in the second period, chlorine in the third period, bromine in the fourth period, and iodine in the fifth period. which element has the largest first ionization energy?

a. fluorine

b. chlorine

c. bromine

d. iodine

e. you need more data to predict the first ionization energy of these elements.

Explanation:

Step1: Recall ionization energy trend

First ionization energy (IE) generally increases across a period (left to right) and decreases down a group (top to bottom) in the periodic table. This is because as you move down a group, the atomic radius increases (electrons are in higher energy levels, farther from the nucleus), so the outermost electron is less strongly attracted to the nucleus, requiring less energy to remove.

Step2: Analyze the group 17 elements

Fluorine (F), chlorine (Cl), bromine (Br), and iodine (I) are all in Group 17 (halogens). Fluorine is in the second period, chlorine in the third, bromine in the fourth, and iodine in the fifth. Moving down the group (from F to Cl to Br to I), the atomic radius increases, and thus the first ionization energy decreases. So the element at the top of the group (fluorine) will have the largest first ionization energy among them.

Answer:

A. fluorine