Chapter 7.2, Problem 10SP

(a)

Interpretation Introduction

Interpretation: The formula of an ionic compound formed when potassium reacts with iodine needs to be determined.

Concept Introduction: Electron dot structures of an element represent the number of electron/s present in its valance electron shell. In the electron dot structure, a symbol of an atom of an element is written and the number of valance electrons is arranged in pairs represented as dots around the symbol.

For example, the number of valance electrons in a bromine atom is 7; thus, its electron dot structure is represented as follows:

  

Answer to Problem 10SP

  

Explanation of Solution

The given elements are potassium and iodine. Here, potassium is metal and belongs to group 1. It has 1 valance electron which can be easily donated to form potassium cation. Similarly, iodine belongs to group 17. It has 7 valence electrons. It requires 1 electron to complete its octet. It can easily gain one electron from potassium to form a chloride ion. The ionic compound so formed will be potassium chloride or KCl.

This can be explained using electron dot structures as follows:

  

(b)

Interpretation Introduction

Interpretation: The formula forthe ionic compound formed when aluminum reacts with oxygen needs to be determined.

Concept Introduction:The electron dot structure of an element represents the number of electron/s present in its valance electron shell. In the electron dot structure, a symbol of an atom of an element is written and the number of valance electrons is arranged in pairs represented as dots around the symbol.

For example, the number of valance electrons in a bromine atom is 7; thus, its electron dot structure is represented as follows:

  

Answer to Problem 10SP

  

Explanation of Solution

The given elements are aluminum and oxygen. Here, aluminum is a metal and belongs to group 13. It has 3 valance electrons which can be easily donated to form an aluminumcation. Similarly, oxygen belongs to group 16. It has 6 valence electrons. It requires 2 electrons to complete its octet and form oxide. The ionic compound so formed will be aluminum oxide. Since ionic compounds are electrically neutral; thus, 2 Al ions combine with 3 O ions to form y1 ${\text{Al}}_{\text{2}}{\text{O}}_{\text{3}}$ .

This can be explained using electron dot structures as follows: