Technetium or Masurium Facts

Technetium (Masurium) 

Atomic Number: 43

Symbol: Tc

Atomic Weight: 98.9072

Discovery: Carlo Perrier, Emilio Segre 1937 (Italy) found it in a sample of molybdenum that had been bombarded with neutrons; erroneously reported Noddack, Tacke, Berg 1924 as Masurium.

Electron Configuration: [Kr] 5s² 4d⁵

Word Origin: Greek technikos: an art or technetos: artificial; this was the first element made artificially.

Isotopes: Twenty-one isotopes of technetium are known, with atomic masses ranging from 90-111. Technetium is one of two elements with Z < 83 with no stable isotopes; all of technetium's isotopes are radioactive. (The other element is promethium.) Some isotopes are produced as uranium fission products.

Properties: Technetium is a silvery-gray metal that tarnishes slowly in moist air. Common oxidation states are +7, +5, and +4. The chemistry of technetium is similar to that of rhenium. Technetium is a corrosion inhibitor for steel and is an excellent superconductor at 11K and below.

Uses: Technetium-99 is used in many medical radioactive isotope tests. Mild carbon steels may be effectively protected by minute quantities of technetium, but this corrosion protection is limited to closed systems because of technetium's radioactivity.

Element Classification: Transition Metal

Technetium Physical Data

Density (g/cc): 11.5

Melting Point (K): 2445

Boiling Point (K): 5150

Appearance: silvery-gray metal

Atomic Radius (pm): 136

Covalent Radius (pm): 127

Ionic Radius: 56 (+7e)

Atomic Volume (cc/mol): 8.5

Specific Heat (@20°C J/g mol): 0.243

Fusion Heat (kJ/mol): 23.8

Evaporation Heat (kJ/mol): 585

Pauling Negativity Number: 1.9

First Ionizing Energy (kJ/mol): 702.2

Oxidation States: 7

Lattice Structure: Hexagonal

Lattice Constant (Å): 2.740

Lattice C/A Ratio: 1.604 

Sources:

• CRC Handbook of Chemistry & Physics (18th Ed.)
• Crescent Chemical Company (2001)
• Lange's Handbook of Chemistry (1952)
• Los Alamos National Laboratory (2001)