Chapter 8, Problem 8.13QP

Write the outer electron configurations for the (a) alkali metals, (b) alkaline earth metals, (c) halogens, (d) noble gases.

Interpretation Introduction

Interpretation:

The outer electron configurations for the alkali metals, alkaline earth metals, halogens and noble gases should be given.

Concept Introduction:

• The elements with same valence electrons have similar properties and are placed in the same group in periodic table.
• Group I, II, VII, and VIII in the periodic table contains 1, 2, 7 and 8 valence electrons respectively.
• The outer electronic configuration of alkali metals, alkaline earth metals, halogens and noble gases is ${\text{ns}}^{\text{1}}$, ${\text{ns}}^2$, ${\text{ns}}^{\text{2}}{\text{np}}^5$ and ${\text{ns}}^{\text{2}}{\text{np}}^6$ respectively.

To find: the outer electron configurations for the alkali metals.

Answer to Problem 8.13QP

The outer electron configurations for the alkali metals are given below.

$\text{Li}$	${\text{2s}}^{\text{1}}$
$\text{Na}$	${\text{3s}}^{\text{1}}$
$\text{K}$	${\text{4s}}^{\text{1}}$
$\text{Rb}$	${\text{5s}}^{\text{1}}$
$\text{Cs}$	${\text{6s}}^{\text{1}}$
$\text{Fr}$	${\text{7s}}^{\text{1}}$

Explanation of Solution

They are group I elements. The outer shell of alkali metals contains one valence electron. Lithium, sodium, potassium, rubidium, cesium, and francium are the alkali metals. The outer electronic configuration of alkali metals is ${\text{ns}}^{\text{1}}$. They are the first group in aperiodic table and are highly electropositive.

Interpretation Introduction

Interpretation:

The outer electron configurations for the alkali metals, alkaline earth metals, halogens and noble gases should be given.

Concept Introduction:

• The elements with same valence electrons have similar properties and are placed in the same group in periodic table.
• Group I, II, VII, and VIII in the periodic table contains 1, 2, 7 and 8 valence electrons respectively.
• The outer electronic configuration of alkali metals, alkaline earth metals, halogens and noble gases is ${\text{ns}}^{\text{1}}$, ${\text{ns}}^2$, ${\text{ns}}^{\text{2}}{\text{np}}^5$ and ${\text{ns}}^{\text{2}}{\text{np}}^6$ respectively.

To find: the outer electron configurations for the alkali metals.

Answer to Problem 8.13QP

The outer electron configurations for the alkaline earth metals are given below.

$\text{Be}$	${\text{2s}}^{\text{2}}$
$\text{Mg}$	${\text{3s}}^{\text{2}}$
$\text{Ca}$	${\text{4s}}^{\text{2}}$
$\text{Sr}$	${\text{5s}}^{\text{2}}$
$\text{Ba}$	${\text{6s}}^{\text{2}}$
$\text{Ra}$	${\text{7s}}^{\text{2}}$

Explanation of Solution

They are group II elements. The outer shell of alkaline earth metals contains two valence electrons. Beryllium, magnesium, calcium, strontium, barium, and radium are the alkaline earth metals. The outer electronic configuration of alkaline earth metals is ${\text{ns}}^2$.

Interpretation Introduction

Interpretation: the outer electron configurations for the alkali metals, alkaline earth metals, halogens and noble gases should be given.

Concept Introduction:

• The elements with same valence electrons have similar properties and are placed in the same group in periodic table.
• Group I, II, VII, and VIII in the periodic table contains 1, 2, 7 and 8 valence electrons respectively.
• The outer electronic configuration of alkali metals, alkaline earth metals, halogens and noble gases is ${\text{ns}}^{\text{1}}$, ${\text{ns}}^2$, ${\text{ns}}^{\text{2}}{\text{np}}^5$ and ${\text{ns}}^{\text{2}}{\text{np}}^6$ respectively.

To find: the outer electron configurations for the alkali metals.

Answer to Problem 8.13QP

The outer electron configurations for the halogens are given below.

$\text{F}$	${\text{2s}}^{\text{2}}{\text{2p}}^5$
$\text{Cl}$	${\text{3s}}^{\text{2}}{\text{3p}}^5$
$\text{Br}$	${\text{4s}}^{\text{2}}{\text{4p}}^5$
$\text{I}$	${\text{5s}}^{\text{2}}{\text{5p}}^5$
$\text{At}$	${\text{6s}}^{\text{2}}{\text{6p}}^5$

Explanation of Solution

They are group VII elements. The outer shell of halogens contains 7 valence electrons. Fluorine, chlorine, bromine, iodine, and astatine are the halogens. The outer electronic configuration of halogens is ${\text{ns}}^{\text{2}}{\text{np}}^5$. All the halogens are highly electronegative so have high reactivity. To obey the octet rule they gain one electron from other atom while reacting.

Interpretation Introduction

Interpretation: the outer electron configurations for the alkali metals, alkaline earth metals, halogens and noble gases should be given.

Concept Introduction:

• The elements with same valence electrons have similar properties and are placed in the same group in periodic table.
• Group I, II, VII, and VIII in the periodic table contains 1, 2, 7 and 8 valence electrons respectively.
• The outer electronic configuration of alkali metals, alkaline earth metals, halogens and noble gases is ${\text{ns}}^{\text{1}}$, ${\text{ns}}^2$, ${\text{ns}}^{\text{2}}{\text{np}}^5$ and ${\text{ns}}^{\text{2}}{\text{np}}^6$ respectively.

To find: The outer electron configurations for the alkali metals.

Answer to Problem 8.13QP

The outer electron configurations for the noble gases are given below.

$\text{He}$	${\text{1s}}^{\text{2}}$
$\text{Ne}$	${\text{2s}}^{\text{2}}{\text{2p}}^{\text{6}}$
$\text{Ar}$	${\text{3s}}^{\text{2}}{\text{3p}}^{\text{6}}$
$\text{Kr}$	${\text{4s}}^{\text{2}}{\text{4p}}^{\text{6}}$
$\text{Xe}$	${\text{5s}}^{\text{2}}{\text{5p}}^{\text{6}}$
$\text{Rn}$	${\text{6s}}^{\text{2}}{\text{6p}}^{\text{6}}$

Explanation of Solution

They are group VIII elements. The outer shell of noble gases contains 8 valence electrons. Helium, neon, argon, krypton, xenon and radon are the alkaline earth metals. The outer electronic configuration of noble gases is ${\text{ns}}^{\text{2}}{\text{np}}^6$. All the noble gases have similar properties. Since the outer shells of noble gases are completely filled, they are highly inactive.