Question

Trends in the periodic table indicate that an element in which of the following periods and groups will have the smallest cation radius?

A) Period 4, Group 1
B) Period 5, Group 17
C) Period 2, Group 2
D) Period 3, Group 16

Answer 1

In the periodic table, cation radius generally decreases from left to right across a period and increases as you move down a group. The element in Period 3, Group 16 (D) will have the smallest cation radius.

Step-by-step explanation:

In the periodic table, the trend for cation radius is that it generally decreases as you move from left to right across a period and increases as you move down a group. This is because as you move across a period, the number of protons and electrons increases, resulting in a stronger attraction between the electrons and the nucleus. As a result, the electrons are pulled closer to the nucleus, leading to a smaller cation radius. On the other hand, as you move down a group, the number of energy levels increases, causing the electrons to be further away from the nucleus and resulting in a larger cation radius.

Given the answer choices, the option that corresponds to the smallest cation radius is Period 3, Group 16 (D). Elements in Group 16 (also known as the Chalcogens) tend to form anions by gaining two electrons, resulting in a smaller cation radius compared to the other options.