TECHNETIUM TC-99M GENERATOR

1st: 686.9kJ/mol2nd: 1470 kJ/mol3rd: 2850 kJ/mol ve viewtalkedit Technetiumis achemical element; it hassymbolTcandatomic number43.‍‍‍‍‍‍​​​‍​​​​​​ It is the lightest element whoseisotopesare allradioactive. Technetium is one of only two elements both preceded and succeeded in the periodic table by elements with stable forms, the other beingpromethium. All available technetium is produced as asynthetic element. Naturally occurring technetium is a spontaneousfission productinuranium oreandthoriumore (the most common source), or the product ofneutron captureinmolybdenumores. This silvery gray, crystallinetransition metallies betweenmanganeseandrheniumingroup 7of theperiodic table, and its chemical properties are intermediate between those of both adjacent elements. The most common naturally occurring isotope is99Tc, in traces only. Many of technetium's properties had been predicted byDmitri Mendeleevbefore it was discovered; Mendeleev noted a gap in his periodic table and gave the undiscovered element the provisional nameekamanganese(Em). In 1937, technetium became the first predominantly artificial element to be produced, hence its name (from the Greektechnetos, 'artificial', +-ium). One short-livedgamma-ray–emittingnuclear isomer,technetium-99m, is used innuclear medicinefor a wide variety of tests, such as bone cancer diagnoses. The ground state of thenuclidetechnetium-99is used as a gamma-ray–free source ofbeta particles. Long-livedtechnetium isotopesproduced commercially are byproducts of thefissionofuranium-235innuclear reactorsand are extracted fromnuclear fuel rods. Because even the longest-lived isotope of technetium has a relatively shorthalf-life(4.21 million years), the 1952 detection of technetium inred giantshelped to prove that stars canproduce heavier elements.