Chapter 25, Problem 91A

Interpretation Introduction

Interpretation:

Bismuth- $211$ decays by alpha emission to yield another radioisotope. The radioisotope is to be identified.

Concept introduction:

A few substances spontaneously produce energy and subatomic particles, a phenomenon known as radioactivity.

Answer to Problem 91A

  $\text{B}\text{i}\to \text{T}\text{I+}\text{H}\text{e}$

  $\text{T}\text{I}\to \text{P}\text{b+}\text{e}$

Explanation of Solution

Step 1

Two radioactive decays of isotopes are given:

First, we have that bismuth- $211$

1. decays to give another radioisotope and emits alpha radiation.
2. The radioisotope produced in the reaction mentioned above decays by beta emission and gives a stable isotope.

Step 2

Alpha emission results in mass number decreasing by 4 whereas atomic number decreases by 2 as shown:

  $\text{B}\text{i}\to \text{T}\text{I+}\text{H}\text{e}$ , to produce thallium- $207$ is the first radioactive decay of Bismuth- $211$ .

Step 3

The thallium emits beta rays and forms a stable nucleus.

  $\text{T}\text{I}\to \text{P}{\text{b+-1}}^{\text{0}}\text{e}$