Enter a clue or pattern or both:
The Clue
Radioactive element (11 letter answer)
The Answer
CALIFORNIUM
Tags
Notes
The answer CALIFORNIUM is so rare that it appears less than once every 2500 puzzles.
Definition
CALIFORNIUM as a noun:
1. (californium, Cf, atomic number 98) = a radioactive transuranic element; discovered by bombarding curium with alpha particles