テクネチウム

Usual valences: 4 and 7; 3 less common; radioactive element, no stable nuclides; most commonly available isotope: 99; resembles rhenium in chemical behavior; burns in fluorine to form penta- and hexafluorides; combines with sulfur at room temperature to form disulfide; with carbon to form TcC (technetium carbide)

Dissolves in neutral or alkaline solution of hydrogen peroxide (H2O2) to give a solution of (TcO4)- (pertechnate ion)

Basic Treatment: Establish a patent airway (oropharyngeal or nasopharyngeal airway, if needed). Suction if necessary. Watch for signs of respiratory insufficiency and assist ventilations if necessary. Administer oxygen by nonrebreather mask at 10 to 15 L/min. Monitor for shock and treat if necessary ... . Anticipate seizures and treat if necessary ... . Perform routine emergency care for associated injuries. For eye contamination, flush eyes immediately with water. Irrigate each eye continuously during transport ... . Do not use emetics. For ingestion, rinse mouth and administer 5 ml/kg up to 200 ml of water for dilution if the patent can swallow, has a good gag reflex, and does not drool ... . Perform routine BLS care as necessary. /Radioactives I, II, and III/

Advanced treatment: Consider orotracheal or nasotracheal intubation for airway control in the patient who is unconscious or is in severe respiratory distress. Monitor cardiac rhythm and treat arrhythmias as necessary ... . Start IV administration of 0.9% saline (NS) or lactated Ringer's (LR). For hypotension with signs of hypovolemia, administer fluid cautiously. Watch for signs fo fluid overload ... . Treat seizures with diazepam or lorazepam ... . Perform routine advanced life support care as needed. Use proparacaine hydrochloride to assist eye irrigation ... . /Radioactives I, II, and III/

天然物の起源Technetium is the 76th most abundant element, but it is so rare that it is not found as astable element on Earth. All of it is artificially produced. Even though natural technetium isso scarce that it is considered not to exist on Earth, it has been identified in the light spectrumfrom stars. Using a spectroscope that produces unique lines for each element, scientists areable to view several types of stars. The resulting spectrographs indicate that technetium existsin the stars and thus the universe, but not on Earth as a stable element. It was the first new element to be produced artificially from another element experimentallyin a laboratory. Today, all technetium is produced mostly in the nuclear reactors of electricalgeneration power plants. Molybdenum-98 is bombarded with neutrons, which then becomesmolybdenum-99 when it captures a neutron. Since Mo-99 has a short half-life of about 66hours, it decays into Tc-99 by beta decay.

使用Technetium is one of the few artificially produced elements that has practical industrial applications.One is that a very small amount (55-ppm) added to iron creates a corrosion-resistantalloy metal. This property is shared with many of the other transition metallic elements, but notwith other artificially produced elements that have higher atomic numbers and are radioactive.A radioisotope of technetium is widely used in nuclear medicine. The patient is injectedwith saline solution containing Tc-99m (the superscript “m” means that the isotope is unstableand that its nuclei holds more energy than the regular Tc-99 nuclei into which it decays). Thismeans that the Tc-99m will start to emit energy and will finally decay and change to the regularnuclei of Tc-99 when injected into the patient. This energy is in the form of very penetratinggamma rays (a strong type of X-rays). The radioactive solution of Tc-99m may be combinedwith other elements that are absorbed by certain organs of the human body being diagnosedor treated. For instance, adding tin to the solution targets the red blood cells, whereas phosphorusin the solution concentrates the radioactive solution in heat muscles. The gamma raysare strong enough to expose an X-ray film that depicts the internal image of the organ underexamination. This procedure is safe because Tc-99m has a half-life of only 6.015 hours, andthe Tc-99 has a half-life of over 200,000 years. However, the radioactivity will be harmless inless than a day because the body rapidly eliminates the residual radioactive solution.Technetium is also used as an alloy metal to produce super-strong magnets that are supercooledto near absolute zero to improve their efficiency. Powerful magnets are used in imagingequipment and possibly in future magnetic driven trains. Its radioactivity makes it useful as atracer in the production of metals and tracing flowing fluids in pipelines.