Chapter U1.20, Problem 4E

Interpretation Introduction

(a)

Interpretation:

Charge on aluminium ion of AlAs needs to be determined.

Concept introduction:

Aluminium belongs to group 13 in the periodic table. The atomic number of aluminium is 13 so it has 3 valence electrons. It is a metal so it can lose electrons to from stable electronic configuration.

Answer to Problem 4E

Charge on aluminium ion in AlAs is + 3.

Explanation of Solution

The number of valence electrons in Al is + 3 thus, it can lose these 3 electrons to from stable ion. After the removal of 3 electrons it forms ${\text{Al}}^{3+}$ ion.

Thus, the charge on Al is + 3.

Interpretation Introduction

(b)

Interpretation:

Charge on arsenic ion in AlAs needs to be determined.

Concept introduction:

Arsenic is a group 15 elements with 5 valence electrons. It can gain electron to from stable electronic configuration.

Answer to Problem 4E

Charge on arsenic ion is -3.

Explanation of Solution

Arsenic belongs to group 15 that is N family. It can gain 3 electrons to from stable electronic configuration thus, the charge on Arsenic will be -3.

Interpretation Introduction

(c)

Interpretation:

The total charge of AlAs needs to be shown zero.

Concept introduction:

As per zero charge rule a compound must be neutral. Positive charge of cation must be counter balanced by anions.

Explanation of Solution

The compound formed is AlAs where charge on Al is + 3 and that of As is -3. Thus, the overall compound is neutral with zero charge.

In AlAs there is one aluminium ion. Total charge of one aluminium ions is $1\left(+3\right)=+3$.

There is one arsenic ion with -3 charges.

So, total charge will be:

$T=+3-3=0$

Interpretation Introduction

(d)

Interpretation:

Total number of valence electrons must be calculated in AlAs.

Concept introduction:

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

Answer to Problem 4E

There are total 8 valence electrons in AlAs.

Explanation of Solution

One aluminium atom has 3 valence electrons. One arsenic atom has 5 valence electrons.

Thus, the total valence electron will be sum of valence electron of Al and As.

T=3 + 5=8.