Chapter 4, Problem 4.68EP

What is the chemical formula of the ionic compound produced through interaction of each of the following pairs of elements?

1. a. Li and S
2. b. Mg and N
3. c. Ca and Cl
4. d. K and F

Interpretation Introduction

Interpretation:

The chemical formula for the ionic compound produced through interaction $\text{Li and S}$ elements is to be written.

Concept Introduction:

Ions are formed by loss or gain of electrons.  The formation of ion requires the presence of two elements, these two elements are: one is metal atom and another one is non-metal atom.  Metal atom loses electron and non-metal atom accepts electron.

The ratio in which positive and negative ions combine is the ratio which achieves charge neutrality for the resulting compound.

There three rules to remember while writing the chemical formulas.  They are as follows:

• First write the symbol for positive ion.
• The charges of the ions are not shown in the formula.
• The numbers in the formula give the combining ratio for the ions.

Answer to Problem 4.68EP

The chemical formula for the ionic compound produced through interaction of $\text{Li and S}$ elements is ${\text{Li}}_{\text{2}}\text{S}$.

Explanation of Solution

Lithium is an element present in IA group and has the ability to lose one electron to attain inert gas configuration of helium atom.  The resultant ion formed by this loss of electron is as follows:

  $\text{Li }\to {\text{ Li}}^{\text{+}}{\text{+ e}}^{-}$

Sulfur atom belongs to VIA group which accepts two electrons to have an octet configuration in its outermost orbital.  The resultant ion formed by the gain of electron is as follows:

  ${\text{S + 2e}}^{\text{-}}\to {\text{ S}}^{\text{2-}}$

Here, $\text{Li}$ will lose one valence electron and $\text{S}$ will gain two electrons.  The charges of $\text{Li}$ and $\text{Cl}$ ions are ${\text{Li}}^{\text{+}}$ and ${\text{S}}^{\text{2-}}$ respectively.

${\text{Li}}^{\text{+}}$ ion combines with  ${\text{S}}^{\text{2-}}$ ions combine in $\text{2 to 1}$ ratio because this combination causes the resultant charges to add to zero.  Two ${\text{Li}}^{\text{+}}$  ions give two units of positive charges.  One ${\text{S}}^{\text{2-}}$ ion result in two units of negative charges.  Thus, the chemical formula for the compound is ${\text{Li}}_{\text{2}}\text{S}$.

Hence, the chemical formula of ionic compound is ${\text{Li}}_{\text{2}}\text{S}$.

Interpretation Introduction

Interpretation:

The chemical formula for the ionic compound produced through interaction of $\text{Mg and N}$ elements is to be written.

Concept Introduction:

Ions are formed by loss or gain of electrons.  The formation of ion requires the presence of two elements, these two elements are: one is metal atom and another one is non-metal atom.  Metal atom loses electron and non-metal atom accepts electron.

The ratio in which positive and negative ions combine is the ratio which achieves charge neutrality for the resulting compound.

There three rules to remember while writing the chemical formulas.  They are as follows:

• First write the symbol for positive ion.
• The charges of the ions are not shown in the formula.
• The numbers in the formula give the combining ratio for the ions.

Answer to Problem 4.68EP

The chemical formula for the ionic compound produced through interaction of $\text{Mg and N}$ elements is ${\text{Mg}}_{\text{3}}{\text{N}}_{\text{2}}$.

Explanation of Solution

Magnesium element belongs to IIA group and has the ability to lose two electrons to attain inert gas configuration of Neon atom.  The resultant ion formed by this loss of two electrons is as follows:

  $\text{Mg }\to {\text{Mg}}^{\text{2+}}{\text{+2e}}^{\text{-}}$

Nitrogen atom belongsto VA group which accepts three electrons to have octet configuration in its outermost orbital.  The resultant ion formed by the gain of electron is as follows:

  ${\text{N + 3e}}^{\text{-}}\to {\text{ N}}^{\text{3-}}$

Here, $\text{Mg}$ will lose two valence electrons and $\text{N}$ will gain three electrons.  The charges of $\text{Mg}$ and $\text{N}$ ions are ${\text{Mg}}^{\text{2+}}$ and ${\text{N}}^{3-}$ respectively.

${\text{Mg}}^{\text{2+}}$ ion combines with  ${\text{N}}^{3-}$ ions combine in $\text{3 to 2}$ ratio because this combination causes the resultant charges to add to zero.  Three ${\text{Mg}}^{\text{2+}}$ ions give three units of positive charges. Two ${\text{N}}^{3-}$ ions result in six units of negative charges.  Thus, the chemical formula for the compound is ${\text{Mg}}_{\text{3}}{\text{N}}_{\text{2}}$.

Hence, the chemical formula of ionic compound is ${\text{Mg}}_{\text{3}}{\text{N}}_{\text{2}}$.

Interpretation Introduction

Interpretation:

The chemical formula for the ionic compound produced through interaction of $\text{Ca and Cl}$ elements is to be written.

Concept Introduction:

Ions are formed by loss or gain of electrons.  The formation of ion requires the presence of two elements, these two elements are: one is metal atom and another one is non-metal atom.  Metal atom loses electron and non-metal atom accepts electron.

The ratio in which positive and negative ions combine is the ratio which achieves charge neutrality for the resulting compound.

There three rules to remember while writing the chemical formulas.  They are as follows:

• First write the symbol for positive ion.
• The charges of the ions are not shown in the formula.
• The numbers in the formula give the combining ratio for the ions.

Answer to Problem 4.68EP

The chemical formula for the ionic compound produced through interaction of $\text{Ca and Cl}$ elements is ${\text{CaCl}}_{\text{2}}$.

Explanation of Solution

Calcium element belongs to IIA group and has the ability to lose two electrons to attain inert gas configuration of Neon atom.  The resultant ion formed by this loss of two electrons is as follows:

  $\text{Ca }\to {\text{ Ca}}^{\text{2+}}{\text{+ 2e}}^{\text{-}}$

Chlorine atom belongsto VIIA group which accepts one electron to have octet configuration in its outermost orbital.  The resultant ion formed by the gain of two electrons is as follows:

  ${\text{Cl + e}}^{\text{-}}\to {\text{ Cl}}^{\text{-}}$

Here, $\text{Ca}$ will lose two valence electrons and $\text{Cl}$ will gain one electron.  The charges of $\text{Ca}$ and $\text{S}$ ions are ${\text{Ca}}^{\text{2+}}$ and ${\text{Cl}}^{\text{-}}$ respectively.

${\text{Ca}}^{\text{2+}}$ ion combines with  ${\text{Cl}}^{\text{-}}$ ions combine in $\text{1 to 2}$ ratio because this combination causes the resultant charges to add to zero.  One ${\text{Ca}}^{\text{2+}}$  ion gives two units of positive charges.  Two ${\text{Cl}}^{\text{-}}$ ions result in two units of negative charges.  Thus, the chemical formula for the compound is ${\text{CaCl}}_{\text{2}}$.

Hence, the chemical formula of ionic compound is ${\text{CaCl}}_{\text{2}}$.

Interpretation Introduction

Interpretation:

The chemical formula for the ionic compound produced through interaction of $\text{K and F}$ elements is to be written.

Concept Introduction:

Ions are formed by loss or gain of electrons.  The formation of ion requires the presence of two elements, these two elements are: one is metal atom and another one is non-metal atom.  Metal atom loses electron and non-metal atom accepts electron.

The ratio in which positive and negative ions combine is the ratio which achieves charge neutrality for the resulting compound.

There three rules to remember while writing the chemical formulas.  They are as follows:

• First write the symbol for positive ion.
• The charges of the ions are not shown in the formula.
• The numbers in the formula give the combining ratio for the ions.

Answer to Problem 4.68EP

The chemical formula for the ionic compound produced through interaction of $\text{K and F}$ elements is $\text{KF}$.

Explanation of Solution

Potassium element belongs to IA group and has the ability to lose one electron to attain inert gas configuration of Neon atom.  The resultant ion formed by this loss of two electrons is as follows:

  $\text{K }\to {\text{ K}}^{\text{+}}{\text{+ e}}^{\text{-}}$

Fluorine atom belongsto VIIA group which accepts one electron to have octet configuration in its outermost orbital.  The resultant ion formed by the gain of one electron is as follows:

  ${\text{F + e}}^{\text{-}}\to {\text{F}}^{\text{-}}$

Here, $\text{K}$ will lose one valence electron and $\text{F}$ will gain three electrons.  The charges of $\text{K}$ and $\text{F}$ ions are ${\text{K}}^{\text{+}}$ and ${\text{F}}^{\text{-}}$ respectively.

${\text{K}}^{\text{+}}$ ion combines with  ${\text{F}}^{\text{-}}$ ions combine in $\text{1 to 1}$ ratio because this combination causes the resultant charges to add to zero.  One ${\text{K}}^{\text{+}}$ ion gives one unit of positive charge.  One ${\text{F}}^{\text{-}}$ ion result in one unit of negative charge.  Thus, the chemical formula for the compound is $\text{KF}$.

Hence, the chemical formula of ionic compound is $\text{KF}$.