Chapter 24, Problem 24.7P

Interpretation Introduction

Interpretation:

Reason for why it is difficult to differentiate positron emission and electron capture from the N/Z ratio of a nuclide has to be explained. Also the factors that are important for these processes have to be described.

Concept Introduction:

Nuclides that are unstable generally decay in a mode that changes its N/Z ratio to the band of stability.

• Nuclides having many neutrons (Neutron-rich nuclides) have a high N/Z ratio and lies above the band of stability. Therefore, to decrease N/Z ratio these nuclides undergo ${\beta }^{-}$ decay.
• Nuclides having many protons (Proton-rich nuclides) have a low N/Z ratio and lies below the band of stability. Therefore, to increase N/Z ratio these nuclides undergo $e^{-}$ capture and/or ${\beta }^{+}$ decay. Heavier elements mostly undergo $e^{-}$ capture whereas lighter elements undergo ${\beta }^{+}$ emission.
• Nuclides having $Z>83$ are considered as too heavy to be stable. To decrease the values of Z and N, it undergoes $\alpha$ decay.

Nuclear reaction: A nuclear reaction in which a lighter nucleus fuses together into new stable nuclei or a heavier nucleus split into stable daughter nuclei with the release of large amount of energy.

Common particles in radioactive decay and nuclear transformations are mentioned below,

  $\begin{array}{cc}\text{Particle}& \text{Symbol}\\ \text{Proton}& {}_{\text{1}}^{\text{1}}\text{H}\text{or}{}_{\text{1}}^{\text{1}}\text{P}\\ \text{Neutron}& {}_{\text{0}}^{\text{1}}\text{n}\\ \text{Electron}& {}_{\text{-1}}^{\text{0}}\text{e}\\ \text{Alpha}\text{particle}& {}_{\text{2}}^{\text{4}}\text{He}\text{or}{}_{\text{2}}^{\text{4}}\text{α}\\ \text{Beta}\text{particle}& {}_{\text{-1}}^{\text{0}}\text{e}\text{or}{}_{\text{-1}}^{\text{0}}\text{β}\\ \text{Positron}& {}_{\text{1}}^{\text{0}}\text{e}\end{array}$