Every stable isotope is non radioactive. That is the definition of "stable." It is possible protons have a half life, but if so it exceeds 6.6 decillion years. Hydrogen and deuterium are stable. Tritium (H3) has a half life of about 12 years.
hydrogen-1hydrogen-2carbon-12etc.
bromine (Br2)
Lead 206 (Pb)
This phenomenon is not mandatory.
A stable, nonradioactive atom must be formed.
nonradioactive
bromine (Br2)
hydrogen-1hydrogen-2carbon-12etc.
No, americium is an unstable and radioactive chemical element.
Lead, the isotope Pb 206.
This is impossible.
Lead 206 (Pb)
This phenomenon is not mandatory.
Redioactive element
Aluminium and gold, are natural chemical elements, solid metals, nonradioactive.
A stable, nonradioactive atom must be formed.
This is a radioactive chemical element.