Chapter 19, Problem 18A

Interpretation Introduction

Interpretation: The elements with atomic number greater than 92 and the process of their preparation are to be determined.

Concept introduction: Atomic number of Uranium is 92. Elements with atomic numbers greater than 92 are called Transuranium elements. Due to high value of neutron by proton ratio these elements arenot stable and each of them disintegrates into other elements by radioactive decay.

Answer to Problem 18A

Transuranium elements are synthesized by nuclear transmutation reaction.

Explanation of Solution

In nuclear transmutation reaction, atomic nuclei are bombarded by neutrons or other particles such as proton and alpha particles to form a new nuclide.

All the elements with atomic number greater than 92 are named as transuranium elements. These elements are not natural and are prepared by reaction of suitable nuclei with smaller particles such as neutrons and alpha particles. Particle accelerator is a kind of machine needed to produce high energy particles so that it can penetrate into the nucleus of heavier element.

First transuranium element prepared was neptunium $(Z =93),$ which was synthesized by bombarding uranium ( ${}^{238}U$ ) with neutron.

The balanced equation: ${}_{\text{ 92}}^{\text{ 238}}U+{}_0^{1}n\to {}_{93}^{239}Np{\text{ + }}_{-1}^{0}e$

When plutonium ( $Pu$ ) is bombarded with alpha particle, curium ( $Cm$ ) is formed.

The balanced equation: ${}_{\text{ 94}}^{\text{ 239}}Pu+{}_2^{4}He\to {}_{96}^{242}Cm{\text{ + }}_0^{1}n$

Conclusion

Transuranium elements are synthesized by nuclear transmutation reaction.