Chapter 24, Problem 24.25P

Interpretation Introduction

Interpretation:

Reason for why most stable isotope of calcium is ${}_{20}^{40}Ca$ has to be explained.

Concept Introduction:

Nuclear stability means that the nucleus is stable meaning that it does not spontaneously emit any kind of radioactivity.

Nuclear stability can be explained based on neutron to proton ratio (N/Z) in the nucleus.

For a stable atoms having low atomic number, n/p ratio is close to 1. When atomic number increases N/Z becomes greater than 1.

For a stable nucleus N/P ratio is one and which lies in the belt of stability of graph of number of protons to number neutrons.

When an isotope is above the belt of stability, N/P ratio is high and there exists a beta emission to decrease the stability.

General rules for predicting the nuclear stability is given below,

• If the nucleus contains 2, 8,20, 28, 50,82 or 126 protons or neutrons, then they are generally considered as stable than the nuclei that do not possess these numbers.
• If the nuclei has even number of both protons and neutrons, then they are considered as stable as those with odd number of these particles.
• All isotopes of elements with atomic number higher than 83 are radioactive.