Before the element was found, many of the properties of element 43 were predicted by Dmitri Mendeleev. Mendeleev saw a gap in his periodic table. He named the element in the gap ekamanganese. In 1937 the technetium isotope Tc was the first element to be artificially produced. This gave the element its name. In Greek τεχνητος means "artificial". Most technetium made on Earth is a by-product of fission of uranium-235 in nuclear reactors. It is extracted from nuclear fuel rods. On earth, technetium occurs naturally only in uranium ores as a product of spontaneous fission. The amount of technitium in the ore is very small but has been measured. No isotope of technetium has a half-life longer than 4.2 million years (Tc). This means that its detection in red giants in 1952 helped support the theory that stars can produce heavier elements. it is the first man made element in periodic table