What is the last non radioactive element?

Answer 1

All isotopes of all elements past bismuth are radioactive (and it is believed that even for bismuth all isotopes are radioactive, its most stable isotope just appears to have a halflife several orders of magnitude longer than the age of the universe).

Answer 2

We're not actually 100% certain that there are any elements that are absolutely not radioactive. Some Grand Unified Theories predict that protons are unstable over incredibly long timescales, and if so, no baryonic matter (all elements are baryonic matter) is stable over the very very long term.

The element with the highest atomic number having at least one isotope that is believed to be stable (provided that proton decay does not occur) is lead. 206Pb, 207Pb, and 208Pb are all stable both theoretically and according to the best measurements we can make. The most stable isotope of bismuth is 209Bi, which has an extremely long half-life: about 20,000,000,000,000,000,000 (2x1019) years. This is about 15,000,000,000 times longer than the current estimated age of the universe, and it's likely that no one would have noticed that bismuth-209 was radioactive if it hadn't been studied very closely because theoretical models predicted that it should be unstable. For all real-world applications, bismuth can be regarded as stable and non-radioactive.

This is still much, much shorter than the lowest possible bound on the (hypothetical) proton decay half-life, which recent experiments have indicated cannot be less than about 10,000,000,000,000,000,000,000,000,000,000,000 (1034) years.

Answer 3

Lead is the last element on the Periodic Table that isn't radioactive. It is also the heaviest of the non-radioactive elements.

Answer 4

i have no clue

Answer 5

uranium and titanium

Answer 6

ununocctiium

Answer 7

Bismuth

Answer 8

bismuth

Answer 9

Astatine