Radioactive and Synthetic Elements?

Question

What are Radioactive and Synthetic Elements?

(characterists)

Answer 1

Synthetic elements are those that must be made from other sources, because they have no stable isotopes in nature. Examples are 43Tc99m and 61Pm; all elements higher in atomic number than 83Bi; and isotopes of every element with too few or too many neutrons to exist with their number of protons. There are isotopes of 90Th and 92U that have been around since the big bang that created everything, because their half-lives are in the billions of years. Also, they decay into 84Po, 85At, 86Rn, 87Ra, and 88Fr, and so one can find small amounts of those radioactive elements in nature.

Elements are radioactive because they have too many neutrons in their nuclei for the number of protons. Example, carbon-14, which decays by electron (beta-minus) emission to nitrogen-14.

Others have too few neutrons. Example: Carbon-11, which decays by positron (beta-plus) emission to boron-11.

Others beyond bismuth are just too heavy to be stable. Example: Uranium-238, which decays be alpha emission (ejection of a helium nucleus, 2He4).