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Technetium (Tc)

QUICK REFERENCE

  • Symbol: Tc
  • Atomic Number: 43
  • Atomic Weight: [98]
  • Element Classification: Transition Metal
  • Discovered By: Carlo Perrier and Emilio Segrè
  • Discovery Date: 1937
  • Name Origin: Greek: ‘technetos’ (artificial), reflecting its status as the first element to be artificially produced
  • Density(g/cc): 11.5
  • Melting Point: 2157°C
  • Boiling Point: 4265°C
  • Appearance: Silvery-gray metal
  • Atomic Radius(pm): 183

Discovery

Technetium was the first element to be artificially produced, marking a significant milestone in nuclear chemistry. It was discovered in 1937 by Italian scientists Carlo Perrier and Emilio Segrè, who isolated it from a sample of molybdenum bombarded with deuterons in the Berkeley cyclotron, in California. This discovery filled the gap for element 43 in the periodic table, which had remained vacant despite numerous attempts to find it naturally. Technetium’s name, derived from the Greek word ‘technetos’, meaning artificial, underscores its synthetic origins.

Relation to Other Elements

Technetium is a transition metal, situated in group 7 of the periodic table, between molybdenum and ruthenium. As a transition metal, technetium shares typical properties such as forming colored compounds and having multiple oxidation states, with +4, +6, and +7 being the most common. It resembles rhenium more than it does manganese or ruthenium, especially in chemical behavior and physical properties. Being radioactive, all of technetium’s isotopes are unstable; the most stable isotope, technetium-98, has a half-life of about 4.2 million years.

Natural Occurrence

Technetium is not found naturally on Earth in significant quantities but is present in trace amounts as a product of spontaneous fission of uranium and in the decay of other radioactive elements. The majority of technetium on Earth is produced synthetically in nuclear reactors through the neutron activation of molybdenum targets.

Uses

Despite its scarcity and radioactivity, technetium has several specialized uses:

  • Medical Imaging: The most significant use of technetium is in the field of nuclear medicine, particularly technetium-99m (a metastable nuclear isomer), which is used in various diagnostic tests. Technetium-99m is preferred for its ideal half-life of about 6 hours and the type of radiation it emits, making it useful for imaging bones, heart, and other organs.
  • Industrial Radiography: Some technetium isotopes are used in industrial radiography to detect cracks and defects in metals.
  • Scientific Research: Technetium is used in scientific research, especially in the study of its chemistry and that of its compounds, which can act as catalysts in chemical reactions.

The discovery of technetium filled an important gap in the periodic table and demonstrated that elements not found in nature could be synthesized in the laboratory. Its applications, especially in nuclear medicine, have had a profound impact on healthcare, providing essential diagnostic tools for numerous medical conditions.

Molybdenum (Mo)

Rhodium (Rh)