Chapter 11, Problem 7STP

Interpretation Introduction

Interpretation:

The element that tend to have largest atomic radius in the period should be determined from the given periodic table.

Concept introduction:

A tabular arrangement of the chemical elements by their atomic number in such a way that the elements with same number of valence shell electrons are present in the same vertical columns called groups. The horizontal rows are known as periods. The complete tabular form of elements is known as the Periodic Table. Elements in the same family have similar chemical and physical properties.

Answer to Problem 7STP

The correct option is (c), Y.

Explanation of Solution

Given:

Distance from the nucleus to the valence shell of an atom is said to be its atomic size.

The principal energy level for the elements in the same periods remains same. When moving across the period that is from left to right in the periodic table, addition of one more proton to the nucleus of an atom takes place which results in the increase of nuclear charge by one unit for each step from left to right. Due to increase in nuclear charge, the nucleus of an atom exerts an increasingly strong pull on the electrons present in the valence shell that is valence electrons and thus, atomic radius decreases.

On moving down the group, the electrons are added to higher energy levels and there are more electrons present between nucleus and the valence electrons. Thus, the valence electrons do not feel more attraction towards nucleus. Hence, on moving down the group the atomic size increase.

Hence, the element that tend to have largest atomic radius will be that element which is present at the left side of the periodic table that is, element Y.