Chapter 6, Problem 4STP

Interpretation Introduction

Interpretation:

The sphere which represents ion is to be identified among given.

Concept Introduction :

The electron configuration of an element defines how its electrons are arranged throughout its atomic orbitals. Standard notation is used to represent atomic electron configurations, placing all electron-containing atomic subshells in sequential order. The number of electrons held by the subshell is indicated by superscript.

Answer to Problem 4STP

Sphere A

Explanation of Solution

The atomic number of potassium is $19$ . Its electronic configuration is,

  $1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^1$

Potassium has 19 electrons which is one more than the Nobel gas electronic configuration $\text{Ar}\left(18\right)$ . It is known that elements having noble gas electronic configuration are stable. Thus, potassium losses one electron to form ${\text{K}}^{+}$ .

By losing one electron, no. of electrons decreases but the nuclear charge stays unchanged. So, electrons are held more tightly by the positively charged protons, which leads to a decrease in the size of the ion compared to the atom.

Thus, sphere A represents potassium ion.