Chapter 2, Problem 88A

(a)

Interpretation Introduction

Interpretation: The elements which are abundant both in the human body and Earth’s crust, oceans, and atmosphere need to be identified.

Concept Introduction: An element is a substance that cannot be decomposed further into simpler substances by any chemical process. On the other hand, compounds are composed of two or more elements. They can be decomposed into their elemental components.

Explanation of Solution

Five elements make up 98% of the mass of the human body. These elements are oxygen (61%), carbon (23%), hydrogen (10.0%), nitrogen (2.6%) and calcium (1.4%). Also, from the graph, the five most abundant elements by mass in Earth’s crust, oceans, and atmosphere are silicon, oxygen, iron, calcium, and aluminum.

From the data given, the elements abundant both in the human body and Earth’s crust, oceans and atmosphere are oxygen and calcium.

(b)

Interpretation Introduction

Interpretation: The elements which are abundant in Earth’s crust, oceans, and atmosphere but not in the human body need to be identified.

Concept Introduction: An element is a substance that cannot be decomposed further into simpler substances by any chemical process. On the other hand, compounds are composed of two or more elements. They can be decomposed into their elemental components.

Explanation of Solution

Five elements make up 98% of the mass of the human body. These elements are oxygen (61%), carbon (23%), hydrogen (10.0%), nitrogen (2.6%) and calcium (1.4%). Also, from the graph, the five most abundant elements by mass in Earth’s crust, oceans, and atmosphere are silicon, oxygen, iron, calcium, and aluminum.

From the data given, the elements abundant in Earth’s crust, oceans, and atmosphere but not in the human body are silicon, iron, and aluminum.

(c)

Interpretation Introduction

Interpretation: Whether the compounds found in the human body are the same as of found in rocks, seawater, and air or not needs to be explained.

Concept Introduction: An element is a substance that cannot be decomposed further into simpler substances by any chemical process. On the other hand, compounds are composed of two or more elements. They can be decomposed into their elemental components.

Explanation of Solution

The compounds formed in the human body are not the same as those found in rocks, seawater, and air. The human body mostly contains organic compounds like proteins, minerals, and amino acids. Water is also present in the human body in a high percentage. These compounds are very different from the compounds present in the atmosphere. For example, there are harmful gases like nitrogen and sulfur oxides present in the air which are not there in the human body.