Chapter 6, Problem 10STP

Interpretation Introduction

Interpretation:

It is to be identified whether statement I is correct or not. If the statement I is correct explain the reason given is explaining statement I or not.

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 10STP

Statement I is correct but statement II is incorrect.

Explanation of Solution

The atomic number of calcium is $20$ . Its electronic configuration is,

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

Calcium has 20 electrons which is two more than the Nobel gas electronic configuration of $\text{Ar}\left(18\right)$ . It is known that elements having noble gas electronic configuration are stable. Thus, calcium losses two electrons to form ${\text{Ca}}^{+}$ .

By losing two electrons, no. of electrons decreases but the nuclear charge staysunchanged. 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, a calcium atomis larger than a calcium ion. So, the statement I is correct.

Ions don't need to be always larger than their parent atoms. Cations are smaller than their parent atom while anions are smaller than their parent atoms.

Thus, statement II is incorrect.