What Is Tellurium?
Tellurium, atomic number 52 and symbol Te, is one of the periodic table's metalloids — elements that straddle the line between metal and nonmetal.
A brittle metalloid. Rarer than platinum in Earth's crust. Used in solar cells.
As a metalloid in Period 5 and Group 16 (Oxygen Group / Chalcogens), tellurium's placement on the table reflects its electron configuration of [Kr] 4d¹⁰ 5s² 5p⁴, which governs its bonding behavior and the type of compounds it typically forms.
Position on the Periodic Table
Tellurium is located in Period 5, which continues the transition metal pattern seen in Period 4 but one principal shell further out.
Within that row, tellurium sits in Group 16 (Oxygen Group / Chalcogens), alongside elements that share a similar number of valence electrons and, by extension, similar chemical behavior.
This position is not arbitrary — the periodic table was deliberately organized so that an element's row and column reveal its expected reactivity, bonding pattern, and physical state at a glance.
Physical & Chemical Properties
Tellurium has an atomic mass of 127.600 u and a density of 6.24 g/cm³. Its melting point is 449.5°C and its boiling point is 988°C.
As a metalloid, tellurium conducts electricity better than a typical nonmetal but worse than a true metal, a property known as semiconductivity.
Electron Configuration Explained
Tellurium's electron configuration is [Kr] 4d¹⁰ 5s² 5p⁴, describing how its electrons are distributed across shells and subshells around the nucleus.
Reading the configuration in order shows electrons filling shells of increasing energy, following the standard Aufbau principle that explains how atomic structure builds up across the periodic table.
The outermost (valence) electrons shown in this configuration are what ultimately determine tellurium's chemical reactivity and the type of bonds it forms with other elements.
History & Discovery
Tellurium was formally discovered in 1782, F.J. Müller, identified through the careful isolation and analytical techniques typical of that era's chemical research.
Many elements from this period were anticipated by Dmitri Mendeleev's periodic table, which successfully predicted gaps corresponding to undiscovered elements well before laboratory instruments existed to confirm them directly.
What Is Tellurium Used For?
Tellurium's specific properties make it useful in several applications, including:
- Solar cells (CdTe)
- Steel alloys
- Thermoelectric devices
- Optical discs (DVDs)
- Rubber production
These uses reflect tellurium's underlying classification as a metalloid, since the same properties that define its category in chemistry also determine where it becomes practically useful.
Fun Facts About Tellurium
- Tellurium is so rare that annual world production is only about 500 tonnes.
- Tellurium is element number 52 on the periodic table, in Period 5 and Group 16.
- Its standard atomic mass is 127.600 u, calculated from the natural abundance of its isotopes.
Frequently Asked Questions
What is Tellurium's atomic number?
Tellurium has atomic number 52.
What is Tellurium's chemical symbol?
Tellurium's symbol is Te.
What group and period is Tellurium in?
Tellurium is in Period 5, Group 16 (Oxygen Group / Chalcogens).
What is Tellurium's atomic mass?
Tellurium's standard atomic mass is 127.600 u.