Tecnecium: the first artificial element that saved millions of lives Predicted by Mendeleev, found in cyclotron debris, deadly and incredibly useful — the history of the 43rd cell of the table and the main radiopharmaceutical of modern times. In the periodic table of Dmitry Ivanovich Mendeleev, there is a cell under number 43. For many years, it remained empty. Its inhabitant did not give himself to chemists of the 19th century, hiding from the most persistent hunters for elements. But it turned out that the matter was not in the complexity of separation, but in the very nature of this substance: it simply could not survive on Earth since its formation. Today we know this element as technetium — the first element created artificially, and at the same time the element that saves thousands of lives every day in hospitals around the world. Tecnecium is the only element lighter than lead that does not have stable isotopes. Its place in the table is a triumph of the predictive power of science and at the same time a monument to human ingenuity. 43rd element: Mendeleev's prophecy In 1869, when Dmitry Ivanovich Mendeleev presented his periodic table to the world, there were 63 elements and several empty places in it. He did not just leave gaps — he boldly predicted the properties of yet unknown substances. For the element under number 43, which was located under manganese in the seventh group, the scientist predicted properties, calling it "eka-manganese" (from Sanskrit "eka" — one). In the following decades, chemists searched for the missing element in manganese ores, minerals, and complex residues of chemical production. There were also loud statements about the discovery: the element was called "ilmium", "nipponium", "lurium". However, none of them was confirmed. Today we know why: technetium is radioactive, and its longest-lived isotopes with a half-life of about 4 million years have long disappeared from the Earth's crust since its formation ... Read more