Tellurium forms the oxides tellurium monoxide, tellurium dioxide, and tellurium trioxide. Tellurium copper is an alloy of copper and tellurium. Such elements include boron, silicon, germanium, antimony, selenium, and tellurium. Boron, silicon, germanium, arsenic, antimony, and tellurium are commonly recognised as metalloids. Silicon was used with arsenic, antimony and tellurium crystals. The six commonly recognised metalloids are boron, silicon, germanium, arsenic, antimony, and tellurium. Boron, silicon, germanium, tellurium are semiconductors. The crystal structures of both selenium tetrafluoride and tellurium tetrafluoride are known. Binary compounds with sulfur, selenium, and tellurium also exist. Selenium and tellurium nucleophiles converted the enzyme into an oxidoreductase. A combination of bismuth and tellurium is most commonly used for the thermocouples. Stable isotopes comprise only 33.2% of naturally occurring tellurium. These are formed by oxidizing mixtures of tellurium and selenium with or . His version included a "group b" consisting of oxygen, sulfur, selenium, tellurium, and osmium. The analogous sesquichalcogenides with sulfur, selenium, and tellurium are also known.