The Element Tellurium
Atomic Number: 52
Atomic Weight: 127.60
Melting Point: 722.66 K (449.51°C or 841.12°F)
Boiling Point: 1261 K (988°C or 1810°F)
Density: 6.232 grams per cubic centimeter
Phase at Room Temperature: Solid
Element Classification: Semi-metal
Period Number: 5
Group Number: 16
Group Name: Chalcogen
What's in a name? From the Latin word for earth, tellus.
Say what? Tellurium is pronounced as te-LOOR-ee-em.
History and Uses:
Tellurium was discovered by Franz Joseph Müller von Reichenstein, a Romanian mining official, in 1782. Reichenstein was the chief inspector of all mines, smelters and saltworks in Transylvania. He also had an interest in chemistry and extracted a new metal from an ore of gold, known as aurum album, which he believed was antimony. He shortly realized that the metal he had produced wasn't antimony at all, but a previously unknown element. Reichenstein's work was forgotten until 1798 when Martin Heinrich Klaproth, a German chemist, mentioned the substance in a paper. Klaproth named the new element tellurium but gave full credit for its discovery to Reichenstein. Tellurium is found free in nature, but is most often found in the ores sylvanite (AgAuTe4), calaverite (AuTe2) and krennerite (AuTe2). Today, most tellurium is obtained as a byproduct of mining and refining copper.
Tellurium is primarily used as an alloying agent. Small amounts of tellurium are added to copper and stainless steel to make them easier to machine and mill. Tellurium is also added to lead to increase its strength and resistance to sulfuric acid (H2SO4).
Tellurium forms many compounds, but none that are commercially important. They include: tellourous acid (H2TeO2), tellurium tetrachloride (TeCl4), tellurium dichloride (TeCl2), tellurium trioxide (TeO3), tellurium monoxide (TeO) and sodium telluride (Na2Te).
Estimated Crustal Abundance: 1×10-3 milligrams per kilogram
Estimated Oceanic Abundance: Not Applicable
Number of Stable Isotopes: 5 (View all isotope data)
Ionization Energy: 9.010 eV
Oxidation States: +6, +4, -2
3s2 3p6 3d10
4s2 4p6 4d10