Hydrogen telluride, commonly named tellane or hydrotelluric acid, is the simplest hydrogen compound of tellurium with the molecular formula H2Te. As the heaviest stable neutral chalcogen hydride it is often discussed alongside hydrogen sulfide and hydrogen selenide, sharing similar chemistry but differing in stability and acidity. For general reference see hydrogen telluride.

Physical and chemical properties

H2Te is a colorless gas at ambient conditions with a strong, unpleasant odor. The molecule is bent and polar, and it is much less thermally stable than lighter hydrides in the same group. In aqueous solution it behaves as an acid, releasing telluride-related species; its conjugate base is derived from the telluride ion. For composition details see tellurium and hydrogen.

Preparation and reactions

In the laboratory hydrogen telluride is commonly generated by treating metal tellurides with a strong acid. For example, acidification of sodium telluride produces H2Te and a soluble sodium salt. The gas is a reducing agent and reacts with many metal ions to form metal tellurides; it also oxidizes readily in air and can decompose to elemental tellurium under some conditions. Related telluride salts are discussed at telluride salts.

Uses and importance

Industrial and commercial uses of H2Te are limited because of its toxicity and instability. It is used in controlled gas-phase chemistry to deposit tellurium-containing films and to synthesize metal tellurides that are important in electronic and photovoltaic materials. In research it serves as a convenient reagent when a gaseous tellurium source is required.

Hazards and handling

  • Hydrogen telluride is highly toxic by inhalation and may cause severe health effects even at low concentrations.
  • It is a strong reducing agent and reacts with oxidizers; it can produce tellurium deposits on surfaces if it decomposes.
  • Working with H2Te requires engineering controls such as fume hoods, gas monitoring, and appropriate personal protective equipment; consult safety guidance.

Because H2Te sits at the heavy end of the hydrogen chalcogen series it illustrates trends in acidity and stability across the group: acids grow stronger and hydrides become less stable from oxygen down to tellurium. These general chemical relationships help explain both the limited practical uses of hydrogen telluride and the precautions necessary when it is handled in the laboratory or in small-scale production.