Thallium

Thallium, ₈₁Tl

Thallium
Pronunciation	/ˈθæliəm/ ​(THAL-ee-əm)
Appearance	silvery white
Standard atomic weight Ar°(Tl)
	[204.382, 204.385][1]
Thallium in the periodic table
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 Iron Cobalt Nickel Copper Zinc Gallium Germanium Arsenic Selenium Bromine Krypton Rubidium Strontium Yttrium Zirconium Niobium Molybdenum Technetium Ruthenium Rhodium Palladium Silver 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 Gold Mercury (element) Thallium Lead 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 Nihonium Flerovium Moscovium Livermorium Tennessine Oganesson In ↑ Tl ↓ Nh mercury ← thallium → lead
Atomic number (Z)	81
Group	group 13 (boron group)
Period	period 6
Block	p-block
Electron configuration	[Xe] 4f14 5d10 6s2 6p1
Electrons per shell	2, 8, 18, 32, 18, 3
Physical properties
Phase at STP	solid
Melting point	577 K ​(304 °C, ​579 °F)
Boiling point	1746 K ​(1473 °C, ​2683 °F)
Density (near r.t.)	11.85 g/cm3
when liquid (at m.p.)	11.22 g/cm3
Heat of fusion	4.14 kJ/mol
Heat of vaporization	165 kJ/mol
Molar heat capacity	26.32 J/(mol·K)
Vapor pressure P (Pa) 1 10 100 1 k 10 k 100 k at T (K) 882 977 1097 1252 1461 1758
Atomic properties
Oxidation states	−5,[2] −2, −1, +1, +2, +3 (a mildly basic oxide)
Electronegativity	Pauling scale: 1.62
Ionization energies	1st: 589.4 kJ/mol 2nd: 1971 kJ/mol 3rd: 2878 kJ/mol
Atomic radius	empirical: 170 pm
Covalent radius	145±7 pm
Van der Waals radius	196 pm
Spectral lines of thallium
Other properties
Natural occurrence	primordial
Crystal structure	​hexagonal close-packed (hcp)
Speed of sound thin rod	818 m/s (at 20 °C)
Thermal expansion	29.9 µm/(m⋅K) (at 25 °C)
Thermal conductivity	46.1 W/(m⋅K)
Electrical resistivity	0.18 µΩ⋅m (at 20 °C)
Magnetic ordering	diamagnetic[3]
Molar magnetic susceptibility	−50.9×10−6 cm3/mol (298 K)[4]
Young's modulus	8 GPa
Shear modulus	2.8 GPa
Bulk modulus	43 GPa
Poisson ratio	0.45
Mohs hardness	1.2
Brinell hardness	26.5–44.7 MPa
CAS Number	7440-28-0
History
Naming	after Greek thallos, green shoot or twig
Discovery	William Crookes (1861)
First isolation	Claude-Auguste Lamy (1862)
Isotopes of thallium v e
Main isotopes[5] Decay abun­dance half-life (t1/2) mode pro­duct 201Tl synth 3.0421 d ε 201Hg 203Tl 29.5% stable 204Tl synth 3.78 y β− 204Pb ε + β+ 204Hg 205Tl 70.5% stable
Category: Thallium view talk edit | references

Thallium is at chemical element, it has symbol Tl and atomic number 81. Its standard atomic weight is 204.4. It is found in Group 15 of the periodic table. Thallium is a soft, heavy and gray metal, but can look red due to oxidation. Thallium and its compounds are extremely toxic, even more than cyanide and arsenic.

1. ↑ "Standard Atomic Weights: Thallium". CIAAW. 2009.
2. ↑ Dong, Z.-C.; Corbett, J. D. (1996). "Na₂₃K₉Tl_15.3: An Unusual Zintl Compound Containing Apparent Tl₅⁷⁻, Tl₄⁸⁻, Tl₃⁷⁻, and Tl⁵⁻ Anions". Inorganic Chemistry. 35 (11): 3107–12. doi:10.1021/ic960014z. PMID 11666505.
3. ↑ Lide, D. R., ed. (2005). "Magnetic susceptibility of the elements and inorganic compounds". CRC Handbook of Chemistry and Physics (PDF) (86th ed.). Boca Raton (FL): CRC Press. ISBN 0-8493-0486-5.
4. ↑ Weast, Robert (1984). CRC, Handbook of Chemistry and Physics. Boca Raton, Florida: Chemical Rubber Company Publishing. pp. E110. ISBN 0-8493-0464-4.
5. ↑ Kondev, F. G.; Wang, M.; Huang, W. J.; Naimi, S.; Audi, G. (2021). "The NUBASE2020 evaluation of nuclear properties" (PDF). Chinese Physics C. 45 (3): 030001. doi:10.1088/1674-1137/abddae.