The people didn't realize the potential danger of using radioactive elements.
Some radioactive elements have uses in nuclear medicine for diagnosis treatment or research.
Also in the box is a device that contains a small amount of a radioactive element.
Every radioactive element or isotope has something called a half life.
So far, the tests show no contamination from radioactive elements.
These products are themselves radioactive elements, each with an atomic weight a little lower than its predecessor.
In addition, research has led to the discovery and creation of additional radioactive elements.
It is a radioactive element that does not exist in nature.
Besides, the radioactive elements whose energy had driven the process were giving out.
Together with Technetium, these are the only two radioactive elements below lead.
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