While working on his periodic chart, Russian chemist Dmitri Mendeleyev (1834-1907) noticed that the sequence did not match and correctly surmised that more elements were yet to be discovered.

eka (one), dvi (two) and tri (three) are the Sanskrit words he used to identify them (three). The first, second, and third elements below a well-known one were all represented by these three symbols.

Oncology's door is wide open.
We know the colors of gold (yellow), lithium (white), silver (brilliant light gray), and lithium (silver gray), but we have no idea what astatine (At) is. The atomic number 85 of this element, which corresponds to Mendeleev's ekaiode, is below that of iodine, making it the least common element on Earth. Its abundance is estimated at less than one gram at any given time.

As a result, it is extremely rare, with a disintegration time of just over seven hours. As if that wasn't strange enough, astatine is a radioactive material that necessitates extremely strict safety regulations in laboratories. However, current research suggests that radioactivity could be a game changer in the fight against cancer, and this is a huge potential.

Radiopharmaceutical application of the isotope 211-At is possible because its nucleus is capable of releasing energy in the form of alpha particles that could be deposited in a space smaller than the diameter of an individual cancer cell.

It was a long journey for him to discover what he was looking for.
After its discovery in the 1930s and 1940s, several researchers got to work. Fred Allison, who claimed to have discovered it and dubbed it "alabamine," was one of the first. The discovery of him was then disavowed because the method utilized was later proved to be erroneous.

X-ray analysis by Horia Hulubei and Yvette Cauchois led them to believe that they had located it. The element was given the name "dor" by the discoverers, although this discovery was not taken for granted by the scientific community.

Anglohelvetium was discovered in 1942 by Walter Minder and Alice Leigh-Smit, who were the third participants in the battle for the helvetium. Method and results were rejected, however.

Traude Bermert and Berta Karlik, who synthesized astatine as well as 211-At, took the following and final turn, as there are no three without four.

One of Marie Curie's disciples
Frankium (Fr), the second rarest element on Earth, is located just two places from astatine in the periodic table. It is estimated that the amount of this alkaline metal in the earth's crust does not surpass 30 grams. Radioactive chemical element that breaks down into radon and astatine when it decomposes is called astatine.

Marie Curie's immediate associate, Marguerite Chaterine Perey, discovered it in 1939, and she was instrumental in its discovery. She got it while purifying actinium-contaminated lanthanum samples. For Mendeleev's periodic chart of ninety-two elements, francium was the last natural element to be identified.

As a result of its scarcity and volatility, francium has no commercial use at now. It is solely employed for scientific purposes, primarily in spectroscopy.