Chapter 39, Problem 67A

Uranium-238 absorbs a neutron and then emits a beta particle. Show that the result is neptunium-239.

To determine

Proof for Neptunium due to emission one beta particle from Uranium by absorbing one neutron.

Explanation of Solution

Introduction:

The number of proton in the nucleus of new element increase by one unit due to decay of one beta particle from any element because tone neutron changes to proton.

The atomic mass number of uraniuum-238 is 238. The atomic number of new element increases by one unit due to decay of one beta particle. Uranium-238 also absorbs one neutron. So, the number of neutron in new elements is also increases by one unit. The atomic mass number of new element also increases by one unit due absorb of one neutron by uranium-238. So, the atomic mass number of new element becomes 239.

The expression for decay of one beta particle from Uranium-238 and absorb of one neutron by uranium is,

${}_{92}^{238}\text{U}+n{\to }_{93}^{239}\text{Ne}{+}_{-1}^0\text{β}$

The new element is neptunium because the number of protons in the nucleus of neptunium is 93 and atomic mass number is 239.

Conclusion:

Thus, the new element is neptunium because the number of protons in the nucleus of neptunium is 93 and atomic mass number increases by one unit due to absorbing of one neutron.