An Overview about the Chemical Element Technetium


Symbol: Tc

Atomic Number: 43

Atomic Mass: 98.0 amu (atomic mass units)

Melting Point: 2200.0°C (2473.15 K, 3992.0°F)

Boiling Point: 4877.0°C (5150.15 K, 8810.6°F)

Number of Protons: 43

Number of Electrons: 43

Number of Neutrons: 55

Classification: Transition Metal

Crystal Structure: Hexagonal

Density @ 293 K: 11.5 grams per cubic centimeter

Color: Silver/gray

When Dmitri Mendeleev first placed all the known elements of his time in the periodic table there were a number of missing elements. The element with atomic number 43 was one of these missing elements. Mendeleev speculated that element 43, to which he gave the name eka-manganese, would have chemical properties similar to the element manganese. In 1925, a report of element 43 being discovered along with the element rhenium was made by Walter Noddack, Ida Tacke and Otto Berg they named element 43 masurium. Unfortunately, they were not able to get any repeat experiments to produce the same results and their discovery of element 43 was discredited.

In 1937, Italian scientists Carlo Perrier and Emilio Segre were able to produce element 43 in repeated experiments. The element was produced by bombarding a molybdenum target with deuterons (deuterium nuclei) which had been accelerated within a cyclotron. It was the first of the man-made elements to be produced and its name reflects this fact as it come from the Greek “tecknikos” which means artificial. Although no natural source of this element has been found on earth spectroscopic analysis of S-, M- and N- type stars has shown the spectral lines typical of technetium. This element being found in stellar material is leading to new theories on the way heavy elements are produced in stars.

The silver/gray metal will tarnish slowly in moist air. All of the isotopes of technetium are unstable and radioactive. Over forty isotopes of this element have been discovered the most stable being technetium-98 with a half life of 4,200,000 years. Technetium-98 decays by beta emission to become ruthenium-98.

Until the early sixties there was very little technetium available. With the growth of the nuclear industry, it is now possible to produce the element in quantity (kilograms rather than grams) as it is a product of uranium decay within reactors.

It has a few uses but its inherent radioactivity has limited its widespread use.

* In closed systems a small amount of ammonium pertechate will protect steel from corrosion.

* Technetium-95 with a half-life of twenty hours is used as a radioactive medical tracer.

* Technetium is a superconductor at 11K.

* The element is used in the calibration of particle detectors