Chapter 7, Problem 36A

(a)

Interpretation Introduction

Interpretation: The number of electrons lost or gained by ${\text{Br}}^{-}$ ion needs to be determined.

Concept Introduction: Metals can lose electron/s to form positively charged ions. Here, the charge on the ion is equal to the number of electrons lost by it. Similarly, non-metals can gain electron/s to form negatively charged ions. Here, the charge on the ion is equal to the number of electrons gained by it.

Explanation of Solution

The given ion is ${\text{Br}}^{-}$ . Here, bromine is a non-metal also it has a negative charge; thus, it gains an electron. Since the bromine atom has a -1 charge, thus, 1 electron is gained by Br atom.

Therefore, the number of electrons gained by ${\text{Br}}^{-}$ ion is 1.

(b)

Interpretation Introduction

Interpretation: The number of electrons lost or gained by ${\text{Na}}^{+}$ ion needs to be determined.

Concept Introduction: Metals can lose electron/s to form positively charged ions. Here, the charge on the ion is equal to the number of electrons lost by it. Similarly, non-metals can gain electron/s to form negatively charged ions. Here, the charge on the ion is equal to the number of electrons gained by it.

Explanation of Solution

The given ion is ${\text{Na}}^{+}$ . Here, sodium is metal; also, it has a positive charge. Thus, it loses an electron. Since the sodium atom has a +1 charge, thus, 1 electron is lost by the Na atom.

Therefore, the number of electrons lost by ${\text{Na}}^{+}$ ion is 1.

(c)

Interpretation Introduction

Interpretation: The number of electrons lost or gained by ${\text{As}}^{3-}$ ion needs to be determined.

Concept Introduction: Metals can lose electron/s to form positively charged ions. Here, the charge on the ion is equal to the number of electrons lost by it. Similarly, non-metals can gain electron/s to form negatively charged ions. Here, the charge on the ion is equal to the number of electrons gained by it.

Explanation of Solution

The given ion is ${\text{As}}^{3-}$ . Here, arsenic is a non-metal also it has a negative charge thus, it gains an electron. Since the arsenic atom has a -3 charge, thus, 3 electrons are gained by As atom.

Therefore, the number of electrons gained by ${\text{As}}^{3-}$ ion is 3.

(d)

Interpretation Introduction

Interpretation: The number of electrons lost or gained by ${\text{Ba}}^{2+}$ ion needs to be determined.

Concept Introduction: Metals can lose electron/s to form positively charged ions. Here, the charge on the ion is equal to the number of electrons lost by it. Similarly, non-metals can gain electron/s to form negatively charged ions. Here, the charge on the ion is equal to the number of electrons gained by it.

Explanation of Solution

The given ion is ${\text{Ba}}^{2+}$ . Here, barium is metal also it has a positive charge; thus, it loses an electron. Since the barium atom has a +2 charge, thus, 2 electrons are lost by the Ba atom.

Therefore, the number of electrons lost by ${\text{Ba}}^{2+}$ ion is 2.

(e)

Interpretation Introduction

Interpretation: The number of electrons lost or gained by ${\text{Ca}}^{2+}$ ion needs to be determined.

Concept Introduction: Metals can lose electron/s to form positively charged ions. Here, the charge on the ion is equal to the number of electrons lost by it. Similarly, non-metals can gain electron/s to form negatively charged ions. Here, the charge on the ion is equal to the number of electrons gained by it.

Explanation of Solution

The given ion is ${\text{Ca}}^{2+}$ . Here, calcium is metal also it has a positive charge. Thus, it loses an electron. Since the calcium atom has a +2 charge, thus, 2 electrons are lost by the Ca atom.

Therefore, the number of electrons lost by ${\text{Ca}}^{2+}$ ion is 2.

(f)

Interpretation Introduction

Interpretation: The number of electrons lost or gained by ${\text{Cu}}^{+}$ ion needs to be determined.

Concept Introduction: Metals can lose electron/s to form positively charged ions. Here, the charge on the ion is equal to the number of electrons lost by it. Similarly, non-metals can gain electron/s to form negatively charged ions. Here, the charge on the ion is equal to the number of electrons gained by it.

Explanation of Solution

The given ion is ${\text{Cu}}^{+}$ . Here, copper is metal and has a positive charge; thus, it loses an electron. Since the copper atom has a +1 charge, thus, 1 electron is lost by the Cu atom.

Therefore, the number of electrons lost by ${\text{Cu}}^{+}$ ion is 1.

(g)

Interpretation Introduction

Interpretation: The number of electrons lost or gained by ${\text{H}}^{-}$ ion needs to be determined.

Concept Introduction: Metals can lose electron/s to form positively charged ions. Here, the charge on the ion is equal to the number of electrons lost by it. Similarly, non-metals can gain electron/s to form negatively charged ions. Here, the charge on the ion is equal to the number of electrons gained by it.

Explanation of Solution

The given ion is ${\text{H}}^{-}$ . Here, hydrogen is a non-metal and has a negative charge; thus, it gains an electron. Since the hydrogen atom has a -1 charge, thus, 1 electron is gained by the H atom.

Therefore, the number of electrons gained by ${\text{H}}^{-}$ ion is 1.

(h)

Interpretation Introduction

Interpretation: The number of electrons lost or gained by ${\text{Cu}}^{2+}$ ion needs to be determined.

Concept Introduction: Metals can lose electron/s to form positively charged ions. Here, the charge on the ion is equal to the number of electrons lost by it. Similarly, non-metals can gain electron/s to form negatively charged ions. Here, the charge on the ion is equal to the number of electrons gained by it.

Explanation of Solution

The given ion is ${\text{Cu}}^{2+}$ . Here, copper is metal and has a positive charge; thus, it loses an electron. Since copper atom has +2 charge thus, 2 electrons are lost by Cu atom.

Therefore, the number of electrons lost by ${\text{Cu}}^{2+}$ ions is 2.