Chapter 9, Problem 118A

(a)

Interpretation Introduction

Interpretation: Most accurate model of the atom among them should be found.

Concept Introduction: An atom is the smallest particle that has the characteristic properties of a chemical element. They are known as the building blocks of matter. There are five different atom models proposed by scientists to explain the structure of an atom.

Answer to Problem 118A

The second model - Rutherford’s atom model, is more accurate than the first one.

Explanation of Solution

The first image represents J.J Thomson’s plum pudding model. It does not discuss the presence of the nucleus. But Rutherford’s model stated that all positive charge and most of the mass of an atom is concentrated at the center portion called the nucleus.

(b)

Interpretation Introduction

Interpretation: State what the positively charged particles on the images imply.

Concept Introduction: An atom is the smallest particle that has the characteristic properties of a chemical element. They are known as the building blocks of matter. There are five different atom models proposed by scientists to explain the structure of an atom.

Answer to Problem 118A

In the first figure, positively charged particles are positive matter in the atom. In the second image, the positive charge represents the nucleus of an atom.

Explanation of Solution

Thomson’s Plum pudding model explains atoms as electrons evenly embedded in a uniform positive charge. Rutherford explained all the positive charge in the atom is concentrated in its nucleus.

(c)

Interpretation Introduction

Interpretation: State what the negatively charged particles represent.

Concept Introduction: An atom is the smallest particle that has the characteristic properties of a chemical element. They are known as the building blocks of matter. There are five different atom models proposed by scientists to explain the structure of an atom.

Answer to Problem 118A

The negatively charged particles represent electrons.

Explanation of Solution

In both the atom models negatively charged particles in the atom are electrons.

(d)

Interpretation Introduction

Interpretation: The subatomic particle missing in both models is to be stated.

Concept Introduction: An atom is the smallest particle that has the characteristic properties of a chemical element. They are known as the building blocks of matter. There are five different atom models proposed by scientists to explain the structure of an atom.

Answer to Problem 118A

The subatomic particle missing in both these models is neutrons.

Explanation of Solution

An atom consists mainly of electrons, protons, and neutrons. Electrons are negatively charged whereas protons are positively charged. But neutral neutrons are missing in both these models.