Question

What changes occur to the atomic number and mass of a nucleus during each of the following decay scenarios?

a) Atomic number increases, mass decreases
b) Atomic number decreases, mass remains constant
c) Atomic number decreases, mass increases
d) Atomic number and mass both decrease

Answer 1

During alpha decay, the atomic number decreases by 2 and the mass number decreases by 4. During beta decay, the atomic number increases by 1 while the mass number remains the same. During electron capture, the atomic number decreases by 1 while the mass number remains the same.

Step-by-step explanation:

During alpha decay, the atomic number decreases by 2 and the mass number decreases by 4. For example, the decay of polonium-212 to lead-208 is represented by: 212Po -> 208Pb + 4He.

During beta decay, the atomic number increases by 1 while the mass number remains the same. For example, carbon-14 undergoes beta decay to form nitrogen-14: 14C -> 14N + 0-1e.

During electron capture, the atomic number decreases by 1 while the mass number remains the same. An example is the capture of an electron by krypton-81 to form bromine-81: 81Kr + 0-1e -> 81Br.