![Tellurium element card: symbol Te, atomic number 52, atomic mass 127.60, electron configuration [Kr] 4d¹⁰ 5s² 5p⁴, oxidation states +6 +4 +2 -2, Metalloid, group 16, period 5, solid at room temperature.](https://stage.chemistry-dictionary.com/wp-content/uploads/2026/09/tellurium-chemical-element.webp)
Tellurium belongs to group 16 on the periodic table, which chemists call the chalcogens. This element is extremely rare, making up a tiny fraction of the Earth’s crust. It is about as rare as platinum, so miners seldom find it in pure form.
Instead, it usually bonds with metals to create minerals called tellurides. A famous example is calaverite, which is a gold telluride compound with the formula AuTe2. In its pure solid state, tellurium has a shiny, silver-white color.
It behaves as a semiconductor, meaning it conducts electricity only under certain conditions. For instance, absorbing light or heat makes the element conduct electricity much better. When heated in air, tellurium burns with a bright greenish-blue flame.
This reaction produces tellurium dioxide, which has the formula TeO2. Tellurium also reacts quickly with halogens like chlorine to make tellurium tetrachloride, or TeCl4. Students often mistake metalloids for simple metals that conduct electricity poorly.
However, tellurium acts as a unique bridge between metallic and nonmetallic behavior. Manufacturers add tellurium to copper to make it easier to cut. This addition does not reduce the ability of copper to conduct electricity.
This makes the alloy very useful in electrical parts and switches. Workers also mix tellurium into rubber to help it resist intense heat. This helps car parts and hoses last much longer under high temperatures.