Chapter 2, Problem 2.25QP

Interpretation Introduction

Interpretation:

It should be explained that why it is impossible for the isotope $\text{H}\text{e}$ to exist.

Concept introduction:

• The elements with same atomic number and different mass number are known as isotopes.
• A graph consists of a Y- axis labeled neutrons, and in X- axis labelled protons, and which is used to identify the stability of elements is known as belt of stability.

• 

• The graph of stable elements is generally referred to as the belt of stability. This graph consists of a Y- axis labeled neutrons, and in X- axis protons where labelled.  At the upper right of the graph radioactive nuclides where located. And their   $\frac{\text{n}}{\text{p}}$ ratio is greater than 1.
• The elements with same atomic number and different mass number are known as isotopes. Most of the elements have isotopes, in which many of them are stable and unstable.
• The ratio between numbers of neutron to the number of proton for an element is referred as $\frac{\text{n}}{\text{p}}$ ratio.
• The elements beyond the atomic number of 83 are only unstable radioactive elements.
• The neutron: proton ratio ( $\frac{\text{n}}{\text{p}}$ ratio) for stable elements is 1:1 and the elements with atomic numbers up to about 20 are stable.
• $\text{Numberof}\text{neutrones}\text{=Mass}\text{numbre}\text{(A)}\text{-}\text{Numberof}\text{protons}\text{(z)}$

To explain: about the belt of stability.