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Technetium is a chemical element with the atomic number 43 and the symbol Tc. It is the lightest element, and all of its isotopes are radioactive; none are stable, with the exception of 97Tc in its completely ionized state. The isotope 99TC is the most common in nature. Nearly all Technetium is synthesized, and only around 18,000 tones can be found in the earth's crust at any given moment. In 1973 Technetium became the first predominantly artificial element to be produced. Hence, its name from the Greek means artificial or synthetic.
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Key takeaways: Uranium, Isotopes, Radioactive, Technetium-99.
Technetium - Introduction
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Technetium is a silvery-grey transition metal with a high melting point. In wet air, it tarnishes slowly. It is soluble in nitric acid, aqua regia (nitro-hydrochloric acid), and concentrated sulphuric acid, but not in hydrochloric acid at any concentration.
- The molecular weight of Technetium is 96.90636
- The most common oxidation states of Technetium are +7,+5, and +4. Technetium (VII) exists as the pertechnetate ion, TcO4-, under oxidizing circumstances.
- Technetium is radioactive in all forms.
It is the lightest element, with an oxidation state of 7 being the most prevalent. It contains three radioactive and unstable isotopes. The following is a list of isotopes and their atomic masses:
- 97 Tc=96.906
- 98Tc=97.907
- 99Tc=98.906
In Uranium ore and Thorium, naturally occurring technetium is a spontaneously efficient product. Neutron capture and molybdenum ores are most commonly obtained from them.
Dmitri Mendeleev predicted several of the features of Technetium before it was discovered. Mendeleev noticed a break in his periodic table and a previously unknown element with the temporary name manganese.
Also Read: Transuranium Elements
Chemical Properties of Technetium
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Technetium is an excellent radioactive tracer because it emits easily detectable 140 keV gamma rays and has a half-life of 6.01 hours, implying that only 6% of it remains after 24 hours. Technetium can attach to a variety of biochemicals due to its chemistry, which impacts how it is metabolized and deposited in the body. Technetium-99m is used in over 50 radiopharmaceuticals. Properties of technetium are as follows:
- Density (g/cc): 11.5
- Melting point (K): 2445
- Boiling point (K): 5150
- Atomic radius (pm): 136
- Covalent radius (pm): 127
- Ionic radius: 56 (+7e)
- Atomic volume (cc/mole): 8.5
- Specific heat (@20°C J/g mole): 0.243
- Fusion heat (kJ/mole): 23.8
- Evaporation heat (kJ/mole): 585
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Physics Properties of Technetium
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- Technetium is a silvery-grey radioactive metal with a platinum-like appearance that is commonly obtained as a grey powder.
- The bulk pure metal has a hexagonal close-packed crystal structure. The cubic crystal structure of the nano disperse pure metal.
- The Tc-99-NMR spectrum of nano disperse technetium is not split, whereas the Tc-99-NMR spectrum of hexagonal bulk technetium is split into 9 satellites.
- Lines having characteristic wavelengths of 363.3 nm, 403.1 nm, 426.2 nm, 429.7 nm, and 485.3 nm are emitted by atomic technetium.
- The metal form is slightly paramagnetic, which means that its magnetic dipoles align with external magnetic fields but revert to random orientations when the field is removed.
- At temperatures below 7.46 K, pure, metallic, single-crystal technetium transforms into a type-II superconductor. Except for niobium, technetium has the largest magnetic penetration depth below this temperature.
Application of Technetium
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- Technetium-99 is used in nuclear medicine for a wide variety of diagnostic tests such as bone cancer diagnosis.
- Technetium's chemistry allows it to bind to a variety of biological components, each of which influences how it is metabolized and deposited in the body, and this single isotope can be employed in a variety of diagnostic procedures. More than 50 commonly used radiopharmaceuticals based on technetium-99m are utilized for imaging and functional evaluations of the brain, heart muscle, thyroid, lungs, liver, gallbladder, kidneys, skeleton, blood, and tumors. The ground state of technetium-99 is employed as a gamma-ray-free beta particle source.
- Technetium, like rhenium and palladium, can act as a catalyst. It is a far more effective catalyst than rhenium or palladium in processes such as the dehydrogenation of isopropyl alcohol. However, its radioactivity is a significant issue in safe catalytic applications.
Isotopes of Technetium
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- Technetium is the lowest-numbered element in the periodic table containing radioactive isotopes, with an atomic number of Z = 43.
- Promethium, the second-lightest exclusively radioactive element, has the atomic number 61. Even when the total number of nucleons (protons + neutrons) is even, atomic nuclei with an odd number of protons are less stable than those with an even number of protons, and odd-numbered elements have fewer stable isotopes.
- Technetium-97 has a half-life of 4.21 million years, 4.2 million years for technetium-98, and 211,100 years for technetium-99.
- Thirty other radioisotopes with mass numbers ranging from 85 to 118 have been identified.
- With the exception of technetium-93 (2.73 hours), technetium-94 (4.88 hours), technetium-95 (20 hours), and technetium-96 (20 hours), the majority of them have half-lives of less than an hour (4.3 days).
- Technetium also has a large number of nuclear isomers, which are isotopes that have one or more excited nucleons. With a half-life of 91 days and excitation energy of 0.0965 MeV, technetium-97m (97mTc; "m" stands for metastability) is the most stable.
Facts about Technetium
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- All technetium isotopes must be handled with caution. Technetium-99, the most prevalent isotope, is a weak beta emitter that is blocked by laboratory glassware walls.
- Nuclear fission produces a large amount of technetium, which spreads more easily than many other radionuclides.
- Technetium has no natural biological function and is not found in the human body.
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Things to Remember
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- Uranium decays naturally into technetium-99. Because it was the first element to be synthesized intentionally, it was given the name technetium, which comes from the Greek word "technètos," which means "artificial." Dmitri Mendeleev, the creator of the periodic table of elements, predicted the existence of technetium for the first time.
- Technetium-99m is a radioactive isotope that is used in radioactive imaging and functional studies of the brain, heart, lungs, gallbladder, thyroid, liver, kidneys, skeleton, and other organs. After being injected into the body, medical imaging equipment detects technetium as it passes through the organ being studied, revealing blood flow and tissue function.
- Technetium is an excellent radioactive tracer because it emits easily detectable 140 keV gamma rays and has a half-life of 6.01 hours, implying that only 6% of it remains after 24 hours.
Sample Questions
Que: Why is Technetium radioactive? (2 marks)
Que: How is Technetium produced? (3 marks)
Que: Why is Technetium unstable? (2 marks)
Que: Which isotopes of Technetium are radioactive?(3 marks)
Que: How is a Technetium scan for the heart done?(2 marks)
Que: Is Technetium safe?(3 marks)
Que: Why is Technetium synthetic? (3 marks)
Que: How is Technetium used to scan Meckel's diverticulum? (3 marks)
Que: Is Technetium a metalloid?(3 marks)
Que: How does Technetium decay? (3 marks)
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