Chapter 4.4, Problem 4.4.3SR

Interpretation Introduction

Interpretation:

The greater first electron affinity containing pair was determined from the given pairs.

Concept Introduction:

First Electron Affinity:

The electron affinity is the amount of energy released during the process when an isolated atom in gaseous phase accepts an electron that results in monovalent gaseous anion.

Example:

${\mathrm{Cl}}_{(g)}+e^{-}\to {\mathrm{Cl}}^{-}{}_{(g)}+349kJ/mol$

The electron affinity gets increases across the periods that are the horizontal rows in the periodic table.

Periodic Table: The available chemical elements are arranged considering their atomic number, the electronic configuration and their properties.  The elements placed on the left of the table are metals and non-metals are placed on right side of the table.

In periodic table the horizontal rows are called periods and the vertical column are called group.

The elements placed on the left of the table are metals which contain its last electron on s-orbital hence considered as s-block elements and the elements placed on the right side of the table contains its last electron in p-orbital which is regarded as p-block elements.

The s and p block elements together are called as main group elements.

The elements with its last electron in d-orbital are called d-block elements also called as transition elements and elements with its last electron in f-orbital are called as inner-transition elements which are usually placed at the bottom of the periodic table.

There are seven periods and 18 groups present in the table and some of those groups are given special name as follows,

$\begin{array}{l}\text{Group-1}\to \text{Alkali metal}\\ \text{Group-2}\to \text{Alkaline metals}\\ \text{Group-16}\to \text{Chalcogens}\\ \text{Group-17}\to \text{Halogens}\\ \text{Group-18}\to \text{Noble gases}\end{array}$

Atomic Number: Atomic number of the element is equal to the number of protons present in the nucleus of the element which is denoted by symbol Z.  The superscript presents on the left side of the symbol of the element.

Shielding effect: The outermost electrons present in the element gets shielded or screened from the nuclear charge by electron present near to the nucleus that is the electrons that surrounds the nucleus (core electrons).

Effective nuclear charge: It is the total positive charge experienced by the valence electrons from the nucleus.