Hydrogen telluride
Hydrogen telluride (tellane) is the inorganic compound with the formula HTe. A hydrogen chalcogenide and the simplest hydride of tellurium, it is a colorless gas. Although unstable in ambient air, the gas can exist at very low concentrations long enough to be readily detected by the odour of rotting garlic at extremely low concentrations; or by the revolting odour of rotting leeks at somewhat higher concentrations. Most compounds with Te–H bonds (tellurols) are unstable with respect to loss of H. HTe is chemically and structurally similar to hydrogen selenide, both are acidic. The H–Te–H angle  is about 90°. Volatile tellurium compounds often have unpleasant odours, reminiscent of decayed leeks or garlic. Synthesis. Electrolytic methods have been developed. HTe can also be prepared by hydrolysis of the telluride derivatives of electropositive metals. The typical hydrolysis is that of aluminium telluride: Other salts of Te such as MgTe and sodium telluride can also be used. NaTe can be made by the reaction of Na and Te in anhydrous ammonia. The intermediate in the hydrolysis, , can be isolated as salts as well. NaHTe, can be made by reducing tellurium with . Hydrogen telluride cannot be efficiently prepared  from its constituent elements, in contrast to HSe. Properties. is an endothermic compound, degrading to the elements at room temperature: Light accelerates the decomposition. It is unstable in air, being oxidised to water and elemental tellurium: It is almost as acidic as phosphoric acid ("K" = 8.1×10), having a "K" value of about 2.3×10. It reacts with many metals to form tellurides.