#52 / 118
52Te127.60
Metalloids (Semimetals)solid at STPP-block

Tellurium

Group: 16Period: 5Standard Atomic Weight: 127.60 u

Why is Tellurium in this position?

Understanding the scientific rationale behind Tellurium's position in the periodic table:

Group Assignment
Group 16

Belongs to Group 16 (Chalcogens) because it has 6 valence electrons (5s² 5p⁴).

Period Assignment
Period 5

Belongs to Period 5 because its outermost electrons occupy n=5.

Orbital Block
P-block

Belongs to the p-block because its valence electrons fill 5p orbitals.

Chemical Category
Metalloids (Semimetals)

Classified as a metalloid due to its semiconductor properties and crystalline brittle metallic luster.

Atomic Structure & Bohr Shell Model

Shell Distribution: [2, 8, 18, 18, 6]

Bohr Atomic Shell Model(2, 8, 18, 18, 6)

Hover or tap any shell orbit ring to inspect electron counts and 2n² capacities.

52 Protons (p⁺)76 Neutrons (n⁰)
KShell K: Electron 1 of 2Shell K: Electron 2 of 2LShell L: Electron 1 of 8Shell L: Electron 2 of 8Shell L: Electron 3 of 8Shell L: Electron 4 of 8Shell L: Electron 5 of 8Shell L: Electron 6 of 8Shell L: Electron 7 of 8Shell L: Electron 8 of 8MShell M: Electron 1 of 18Shell M: Electron 2 of 18Shell M: Electron 3 of 18Shell M: Electron 4 of 18Shell M: Electron 5 of 18Shell M: Electron 6 of 18Shell M: Electron 7 of 18Shell M: Electron 8 of 18Shell M: Electron 9 of 18Shell M: Electron 10 of 18Shell M: Electron 11 of 18Shell M: Electron 12 of 18Shell M: Electron 13 of 18Shell M: Electron 14 of 18Shell M: Electron 15 of 18Shell M: Electron 16 of 18Shell M: Electron 17 of 18Shell M: Electron 18 of 18NShell N: Electron 1 of 18Shell N: Electron 2 of 18Shell N: Electron 3 of 18Shell N: Electron 4 of 18Shell N: Electron 5 of 18Shell N: Electron 6 of 18Shell N: Electron 7 of 18Shell N: Electron 8 of 18Shell N: Electron 9 of 18Shell N: Electron 10 of 18Shell N: Electron 11 of 18Shell N: Electron 12 of 18Shell N: Electron 13 of 18Shell N: Electron 14 of 18Shell N: Electron 15 of 18Shell N: Electron 16 of 18Shell N: Electron 17 of 18Shell N: Electron 18 of 18OShell O: Electron 1 of 6Shell O: Electron 2 of 6Shell O: Electron 3 of 6Shell O: Electron 4 of 6Shell O: Electron 5 of 6Shell O: Electron 6 of 6TeZ = 52

Educational Note: This Niels Bohr planetary model visually illustrates principal quantum energy shells ($n=1, 2, 3\dots$) and electron counts. In modern quantum mechanics (Schrödinger model), electrons do not orbit in fixed circular planetary tracks, but exist as 3D probability clouds (orbitals: $s, p, d, f$) governed by the Heisenberg uncertainty principle.

Electron Shell Filling Breakdown

Shell K (n=1):2 / 2 electrons (100%)
Shell L (n=2):8 / 8 electrons (100%)
Shell M (n=3):18 / 18 electrons (100%)
Shell N (n=4):18 / 32 electrons (56%)
Shell O (n=5):6 / 50 electrons (12%)
Aufbau Electron Configuration
1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 5s² 5p⁴

Neutral ground state configuration. Valence electrons: 6.

Atomic & Quantum Properties

Electronegativity (Pauling)2.1 Pauling
1st Ionization Energy869.3 kJ/mol
Electron Affinity-190.2 kJ/mol
Atomic Radius (empirical)123 pm
Common Oxidation States+4, +6, -2
Crystal StructureHexagonal

Physical & Thermal Properties

Density at STP6.24 g/cm³
Melting Point449.51 °C (722.66 K)
Boiling Point988 °C (1261 K)
Magnetic OrderingDiamagnetic
Discovery Year1782
Discovered ByFranz-Joseph Müller von Reichenstein

Real-World Uses, Occurrence & Compounds

Major Industrial & Everyday Uses
  • Cadmium telluride (CdTe) thin-film utility-scale photovoltaic solar panels
  • Thermoelectric cooling Peltier modules converting heat to electricity (Bi₂Te₃)
  • Free-machining steel and copper alloy additives improving machinability
  • Phase-change optical rewriteable memory discs (CD-RW, DVD-RAM)
Occurrence in Nature

Extracted exclusively as a byproduct of electrolytic copper refining anode slimes; occasionally found as native gold-tellurium ores (calaverite).

Etymology & Name Origin

From Latin 'tellus' meaning Earth (complementing Selenium named after the Moon)

Important Chemical Compounds
CdTe (Cadmium telluride)
Bi₂Te₃ (Bismuth telluride)
TeO₂ (Tellurium dioxide)
Interesting Chemical Facts
  • Tellurium is one of the few elements that readily forms natural chemical bonds with gold, forming mineral tellurides like calaverite during gold rushes.
  • Tellurium has a higher atomic weight (127.60 u) than the next element Iodine (126.90 u), providing a famous historical exception to atomic weight ordering.
  • Absorbing even microgram quantities of tellurium causes the human body to metabolize volatile dimethyl telluride, producing pungent garlic-like breath that persists for months.
Safety & Handling Note

Moderately toxic; exposure causes severe, long-lasting garlic body odor ('tellurium breath') and central nervous system depression.