rhenium [Re]
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Introduction
From the Greek Rhenius, Rhine, a major European river. Discovered in 1925 by German chemists Walter Noaddack, Ida Noddack-Tacke & Otto C Berg.
Occurrence
- does NOT occur in nature as free metal
- occurs in small amounts in the minerals gadolinite & molybdenite
- occurs in earth's crust at 1-4 parts per billion
Characteristics
- obtained either as a powder or as a silver-white hard metal
- resembles manganese
- tarnishes slowly in moist air
- does not react with water under normal conditions
- annealed rhenium is very ductile
- can be bent, coiled & rolled
- rhenium dust can burn or explode
- natural rhenium is a mixture of one stable & one radioactive isotope with a long 1/2 life
- 28 stable isotopes known
Uses
- catalysts
- resistant to poisoning from nitrogen, sulfur & phosphorous
- hydrogenation
- hydrocracking
- reforming & disproportionation of alkenes
- thermocouples
- filaments for mass spectrometers
- thermistors
- tungsten & molybdenum-based alloys
- photoflash lamps
- electrical contact material