Chapter 4, Problem 85A

Interpretation Introduction

Interpretation:

The atomic number and the atomic mass changes when the active atoms participate in alpha, beta and gamma radioactive emission needs to be determined.

Concept introduction:

When the radioactive atom emits the alpha particle its mass and atomic number changes.

The beta decay is emission of an electron from a radioactive atom. There is increasing in the number of proton.

The gamma decay is highly energetic decay, but they are neutral in nature.

Answer to Problem 85A

In the decay of alpha radiation, a new atomform with decrease in the number of protons or neutron.

In the beta radiation, there is increasing in the number of proton by one unit that means atomic number increases by one unit.

There is no change in atomic number and mass of the atom in the gamma radiation.

Explanation of Solution

• The change of atomic number and atomic mass by the decay of alpha particle given as

${ }_Z{X}^A{\to }_{Z-2}{Y}^{A-4}{+}_{2}H{e}^4$

Z = Atomic number.

A = Atomic mass.

X = Radioactive (atom) element before the decay

Y = Element (Atom) after decay

In the above decay reaction shows that the change in the atomic number is two and the atomic mass change by four units.

• The beta decay shown as

${ }_Z{X}^A{\to }_{Z+1}{Y}^A{+}_{-1}{e}^0$

The change in atomic number is +1, and atomic mass remains unchanged.

• The last one decay is gamma decay and change in atomic number and atomic mass is

${ }_Z{X}^A{\to }_Z{Y}^A{+}_0{\Upsilon }^0$

The resultant product shows that there is no change in atomic number and atomic mass.

Conclusion

Always every atom gets the stability of nucleus. The radioactive decay is the type of emission where the atomic number and atomic mass changes for the stability of the nucleus.