Tellurium (Te)

Silvery-gray metalloid

Tellurium is a rare, brittle metalloid used in thermoelectric generators and solar panels, and with two unpaired 5p electrons, tellurium is a p-type semiconductor (bandgap 0.35 eV). Bismuth telluride (Bi₂Te₃) is the best thermoelectric material near room temperature, converting heat directly to electricity.

Key metrics

Density6.24g/cm³

Melting point723K

Boiling point1,261K

Electronegativity2.1Pauling

Discovery

1782discovered

Discovered by: Franz-Joseph Müller von Reichenstein
Reactivity profile: Forms toxic compounds
Reactivity: Medium
Bonding: Covalent

Electron configuration

\textcolor{#6b7280}{[Kr]}\; \textcolor{#22c55e}{4_{d}^{10}}\; \textcolor{#ef4444}{5_{s}^{2}}\; \textcolor{#3b82f6}{5_{p}^{4}}

[Kr] 4d10 5s2 5p4

Wave function

\Psi_{\text{Te}} \approx \frac{1}{\sqrt{52!}} \det \left| \chi_1(\mathbf{r}_1) \dots \chi_{52}(\mathbf{r}_{52}) \right|

Probability density $|\Psi|^2$ across the Te valence shell.

Physical properties

Atomic radius: 123 pm
Ionization energy: 869 kJ/mol
Electron affinity: 190 kJ/mol
Crystal structure: Hexagonal

Oxidation states

-2+4+6

Acid/base

Acidic

Strongly acidicStrongly basic

State at 25 °CSolid

723 K1261 K298 K

Emission spectrum

3 transitions

380450500550600650700780

VioletBlueGreenYellowRed

469.4nmTe I (blue)Blue50%

508.4nmTe I (blue-green)Cyan100%

530.2nmTe I (green)Green70%

Dominant line 508.4 nmRange 469–530 nmTransitions 3