Chapter U1.20, Problem 3E

Interpretation Introduction

(a)

Interpretation:

Charge on lithium ion of Li₃N needs to be determined.

Concept introduction:

Lithium is an alkali metal with valency 1. It belongs to group 1 of the periodic table. It can lose 1 electron to form lithium ion with + 1 charge.

Answer to Problem 3E

Charge on lithium ion in Li₃N is + 1.

Explanation of Solution

As lithium has one valence electron because it belongs to group 1 of the periodic table so it will produce Li ion with + 1 charge.

Interpretation Introduction

(b)

Interpretation:

Charge on nitrogen atom of Li₃N needs to be determined.

Concept introduction:

Nitrogen is a group 15 elements with 5 valence electrons. Thus, it can gain 3 electrons to from stable ion.

Answer to Problem 3E

Charge on nitrogen ion is -3.

Explanation of Solution

As valency of nitrogen is 3 so it will reacts with three monopositive lithium ion to make the compound overall neutral.

Here, N belongs to group 15 so it can take 3 electrons to form stable ion. Thus, the charge on the N is -3.

Interpretation Introduction

(c)

Interpretation:

This is to be shown that charges on the ions added to zero.

Concept introduction:

As per zero charge rule a compound must be neutral. Total positive charge must be equal to total negative charge.

Explanation of Solution

In Li₃N there are three lithium ions. Total charge of three lithium ions is $3\left(+1\right)=+3$.

There is one nitrogen ion with -3 charges.

So, total charge can be calculated as follows:

$T=+3-3=0$

Interpretation Introduction

(d)

Interpretation:

The total number of valence electrons must be calculated in all the atoms of Li₃N.

Concept introduction:

Valence electrons are those which are present in the valance shell of an atom.

Answer to Problem 3E

There are total 8 valence electrons in Li₃N.

Explanation of Solution

Each lithium has one valence electron. So three lithium have 3 valence electrons.

One nitrogen atom has 5 valence electrons. Thus, the total number of valence electrons will be sum of total valence electrons of Li and N.

Thus, total valence electron will be:

$T=3+5=8$