Chapter 4, Problem 4.114QP

Interpretation Introduction

Interpretation: The reason for the negative electron affinity of noble gases should be determined.

Concept Introduction:

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.

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.

Mass number: It is given by the total number of protons and the neutrons present in the nucleus of the element and it is denoted by symbol A. The subscript that lies on the left side of the symbol of the element represents the mass number.

Cation: Removal of electron from the atom results to form positively charged ion called cation.

Anion: Addition of electron to atom results to form negatively charged ion called anion.

The net charge present in the element denotes the presence or absence of electrons in the element.

Atomic radius:

Atomic radius is the distance between the atomic nucleus and outermost electron of an atom.  From the atomic radius, the size of atoms can be visualized.  But there is no specific distance from nucleus to electron due to electron cloud around the atom does not have well-defined boundary.

To identify: The reason for the negative electron affinity of noble gases.