Chapter 10, Problem 51A

(a)

Interpretation Introduction

Interpretation: The representative particle needs to be determined in oxygen gas.

Concept Introduction: In a substance, a representative particle is the smallest unit of the substance in which it naturally exists. For example, for elements, the representative particle is an atom.

The four types of representative particles are as follows:

1. Atom is the smallest particle of an element.
2. Ions are atoms with positive or negative charges.
3. Molecules are formed when two or more atoms are covalently bonded.
4. Formula units are the simplest ratio of ions to form an ionic compound.

Explanation of Solution

Some elements exist as diatomic molecules in nature. Oxygen is one of those elements thus, oxygen occurs as a diatomic molecule naturally that is oxygen gas. Therefore, a representative particle of oxygen gas is the molecule.

(b)

Interpretation Introduction

Interpretation: The representative particle needs to be determined in sodium sulfide.

Concept Introduction: In a substance, a representative particle is the smallest unit of the substance in which it naturally exists. For example, for elements, the representative particle is an atom.

The four types of representative particles are as follows:

1. Atom is the smallest particle of an element.
2. Ions are atoms with positive or negative charges.
3. Molecules are formed when two or more atoms are covalently bonded.
4. Formula units are the simplest ratio of ions to form an ionic compound.

Explanation of Solution

The given substance is sodium sulfide. It is an ionic compound where ions are combined in the simplest ratio. Thus, a representative particle of sodium sulfide is the formula unit.

(c)

Interpretation Introduction

Interpretation: The representative particle needs to be determined in sulfur dioxide.

Concept Introduction: In a substance, a representative particle is the smallest unit of the substance in which it naturally exists. For example, for elements, the representative particle is an atom.

The four types of representative particles are as follows:

1. Atom is the smallest particle of an element.
2. Ions are atoms with positive or negative charges.
3. Molecules are formed when two or more atoms are covalently bonded.
4. Formula units are the simplest ratio of ions to form an ionic compound.

Explanation of Solution

The given substance is sulfur dioxide. It is a molecular compound where atoms are covalently bonded. Thus, a representative particle of sulfur dioxide is a molecule.

(d)

Interpretation Introduction

Interpretation: The representative particle needs to be determined in potassium.

Concept Introduction: In a substance, a representative particle is the smallest unit of the substance in which it naturally exists. For example, for elements, the representative particle is an atom.

Explanation of Solution

The four types of representative particles are as follows:

1. Atom is the smallest particle of an element.
2. Ions are atoms with positive or negative charges.
3. Molecules are formed when two or more atoms are covalently bonded.
4. Formula units are the simplest ratio of ions to form an ionic compound.

The given substance is potassium. It is an element thus representative particle is an atom.