Tellurium

Tellurium, ₅₂Te

Tellurium
Pronunciation	/tɪˈljʊəriəm/ ​(tih-LEWR-ee-əm)
Appearance	sillery lustrous gray
Standard atomic weight Ar, std(Te)	7002127600000000000♠127.60(3)
Mass number	Te:
Tellurium in the periodic cairt
Hydrogen Helium Lithium Beryllium Boron Carbon Nitrogen Oxygen Fluorine Neon Sodium Magnesium Aluminium Silicon Phosphorus Sulfur Chlorine Argon Potassium Calcium Scandium Titanium Vanadium Chromium Manganese Airn Cobalt Nickel Capper Zinc Gallium Germanium Arsenic Selenium Bromine Krypton Rubidium Strontium Yttrium Zirconium Niobium Molybdenum Technetium Ruthenium Rhodium Palladium Siller (element) Cadmium Indium Tin Antimony Tellurium Iodine Xenon Caesium Barium Lanthanum Cerium Praseodymium Neodymium Promethium Samarium Europium Gadolinium Terbium Dysprosium Holmium Erbium Thulium Ytterbium Lutetium Hafnium Tantalum Tungsten Rhenium Osmium Iridium Platinum Gowd Mercur (element) Thallium Leid (element) Bismuth Polonium Astatine Radon Francium Radium Actinium Thorium Protactinium Uranium Neptunium Plutonium Americium Curium Berkelium Californium Einsteinium Fermium Mendelevium Nobelium Lawrencium Rutherfordium Dubnium Seaborgium Bohrium Hassium Meitnerium Darmstadtium Roentgenium Copernicium Ununtrium Flerovium Ununpentium Livermorium Ununseptium Ununoctium Se ↑ Te ↓ Po antimony ← tellurium → iodine
Atomic nummer (Z)	52
Group	group 16 (chalcogens)
Period	period 5
Block	p-block
Element category	Metalloid
Electron confeeguration	[Kr] 4d10 5s2 5p4
Electrons per shell	2, 8, 18, 18, 6
Pheesical properties
Phase at STP	solit
Meltin pynt	722.66 K ​(449.51 °C, ​841.12 °F)
Bylin pynt	1261 K ​(988 °C, ​1810 °F)
Density (near r.t.)	6.24 g/cm3
when liquid (at m.p.)	5.70 g/cm3
Heat o fusion	17.49 kJ/mol
Heat o vapourisation	114.1 kJ/mol
Molar heat capacity	25.73 J/(mol·K)
Vapour pressur P (Pa) 1 10 100 1 k 10 k 100 k at T (K)     (775) (888) 1042 1266
Atomic properties
Oxidation states	−2, −1, +1, +2, +3, +4, +5, +6 (a mildly acidic oxide)
Electronegativity	Pauling scale: 2.1
Atomic radius	empirical: 140 pm
Covalent radius	138±4 pm
Van der Waals radius	206 pm
Spectral lines o tellurium
Ither properties
Naitural occurrence	Te: Primordial
Creestal structur	​hexagonal
Speed o soond thin rod	2610 m/s (at 20 °C)
Thermal conductivity	(1.97–3.38) W/(m·K)
Magnetic orderin	diamagnetic
Young's modulus	43 GPa
Shear modulus	16 GPa
Bulk modulus	65 GPa
Mohs haurdness	2.25
Brinell haurdness	180 MPa
CAS Nummer	13494-80-9
History
Diskivery	Franz-Joseph Müller von Reichenstein (1782)
First isolation	Martin Heinrich Klaproth
Main isotopes o tellurium
Iso­tope Abun­dance Hauf-life (t1/2) Decay mode Pro­duct 120Te 0.09% >2.2×1016 y (β+β+) 120Sn 121Te syn 16.78 d ε 121Sb 122Te 2.55% - (SF) 123Te 0.89% >5×1019 y (ε) 123Sb 124Te 4.74% - (SF) 125Te 7.07% - (SF) 126Te 18.84% - (SF) 127Te syn 9.35 h β− 127I 128Te 31.74% 2.2×1024 y β−β− 128Xe 129Te syn 69.6 min β− 129I 130Te 34.08% 7.9×1020 y β−β− 130Xe
Decay modes in parentheses are predictit, but hae nae yet been observed

Tellurium is a chemical element wi seembol Te an atomic nummer 52. A brickle, mildly toxic, rare, siller-white metalloid that looks seemilar tae tin, tellurium is chemically relatit tae selenium an sulphur. It is occasionally foond in native furm, as elemental crystals. Tellurium is far mair common in the universe as a hale nor it is on Yird. Its extreme rarity in the Yird's crust, comparable tae that o platinum, is pairtly due tae its heich atomic nummer, but it's forbye due tae its furmation o a volatile hydride that caused the element tae be lost tae space as a gas in the het nebular formation o the planet.