non radioactive element
No, americium is an unstable and radioactive chemical element.
This is a radioactive chemical element.
Only the end product of the decay chain of uranium, a non radioactive isotope of lead.
You can use relative dating which is looking at the rocks around it, or you can use radiometric dating, which compares the amount of radioactive element with the amount of nonradioactive element in the rock.
A non-radioactive element is an element that has at least 1 isotope that is not radioactive. The means that at least one isotope has a stable nucleus that does not break down by shooting off high-energy particles.
Before a radioactive atom ceases to undergo further radioactive decay, it must reach a stable configuration or decay into a non-radioactive isotope through the emission of particles or energy. This process continues until the atom reaches a state of stability where it no longer emits radiation.
Sodium does not have naturally occurring radioactive isotopes - as it has only 1 naturally occurring isotope, which has 11 protons and 12 neutrons, and is not radioactive. However, the 18 other known types of sodium isotopes are all radioactive, and sodium-22 (the most stable radioactive sodium isotope) has a half life of 2.6 years.
Sodium primarily exists as stable sodium-23, which is the most common and stable isotope of sodium. However, sodium can also form radioactive isotopes, with sodium-22 being a well-known example that is radioactive.
Redioactive element
This phenomenon is not mandatory.
If you had a stable element 115, then by definition there would need to be at least one non-radioactive isotope. Stable elements are those that have at least one nonradioactive isotope. Of course, the other isotopes of the element could all be radioactive.
The ratio of carbon-14 (radioactive) to carbon-12 (nonradioactive) is measured.