Chapter 39, Problem 54A

To determine

The atomic mass number of new element due to emission of one alpha particle from radium-226.

Explanation of Solution

Introduction:

The number of protons in the nucleus of atom is same as the atomic number and sum of number of neutron and proton in the nucleus of the atom is same as the atomic mass number.

The atomic number reduces by two units and atomic mass number reduces by four units due to emission of one alpha particle from a radioactive element.

The atomic mass number of Radium-226 is 226. If the one alpha particle emits from Radium-226, then the atomic mass number becomes 222 due to reduction of four units in the atomic mass number.

The atomic mass number of new element becomes 222.

Conclusion:

Thus, the atomic mass number of new element becomes 222.