Chapter U1.14, Problem 5E

Interpretation Introduction

Interpretation: Meaning of the diagonal line on the graph of neutrons versus protons is to be explained.

Concept Introduction: An atom or an element exists in many isotopic forms. Some isotopes are found naturally on Earth while some exist due to human activity. Isotopes differ in the number of neutrons.

Answer to Problem 5E

The diagonal line plotted on the graph represents the isotopes that have an equal number of protons and neutrons. It helps to find out the stability of an isotope.

Explanation of Solution

Given information:

A graph of neutrons versus protons is plotted in which there is a diagonal line.

  

There are about 92 naturally occurring elements on the periodic table. Other elements have existed due to some sort of human activity. Elements are found in one or more isotopic forms. To study the stability of nuclei of isotopes, a graph of the number of neutrons versus the number of protons found in stable isotopes of elements is plotted. A reference line is plotted to depict an equal number of protons and neutrons. A diagonal line is obtained. The isotopes falling on this line have an equal number of protons and neutrons. Such isotopes are very stable.

The stability of the nucleus determines the stability of an isotope. An unstable nucleus will disintegrate. There should be a balance between the number of protons and neutrons in the nucleus. Large atoms need more neutrons to make a stable nucleus.

Conclusion

The diagonal line plotted on the graph represents the isotopes that have an equal number of protons and neutrons. Most of the points lie on or above the diagonal line as most elements have neutrons either equal to or greater than the number of protons.