WebElements Periodic Table of the Elements | Thallium

Thallium: the essentials

Brief description: when freshly exposed to air, thallium exhibits a metallic lustre, but soon develops a bluish-grey tinge, resembling lead in appearance. A heavy oxide builds up on thallium if left in air, and in the presence of water the hydroxide is formed. The metal is very soft and malleable. It can be cut with a knife.

The element and its compounds are toxic and should be handled carefully. Thallium may cause cancer.

Table: basic information about and classifications of thallium.
Name: Thallium Symbol: Tl Atomic number: 81 Atomic weight: 204.3833 (2) Standard state: solid at 298 K CAS Registry ID: 7440-28-0	Group in periodic table: 13 Group name: (none) Period in periodic table: 6 Block in periodic table: p-block Colour: silvery white Classification: Metallic

thallium

Nearing Zero cartoon for thallium
Cartoon by Nick D Kim (nearingzero.net, used by permission).

Isolation

Isolation: thallium metal would not normally be made in the laboratory as it is available commercially. Crude thallium is present as a component in flue dust along with arsenic, cadmium, indium, germanium, lead, nickel, selenium, tellurium, and zinc. This is done by dissolving in dilute acid, precipitating out lead sulphate, and then adding HCl to precipitate thallium chloride, TlCl. Further purification can be achieve by electrolysis of soluble thallium salts.

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Cd	In	Sn
Hg	Tl	Pb
Uub	Uut	Uuq

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Thallium
- Essential data: names, symbol, atomic number, and atomic weight; block, period, and group in periodic table; description; standard state; registry number; and isolation
- History: meaning of name; discovery; and history of the element
- Find a property
Thallium around us
- Uses
- Geology: Abundance of elements in the universe; the sun; meteorites; Earth's crust; oceans; and streams
- Biology: Abundance in humans; biological role; and health hazards)
Thallium compounds
- Compounds: halides, oxides, sulfides, hydrides, and complexes; lattice energies; and reduction potentials
- Electronegativities: Pauling; Sanderson; Allred Rochow; Mulliken-Jaffe; and Allen
- Bond enthalpies of diatomic species
- Lattice energies
Element properties
- Physics properties: Boiling point; melting point; density; molar volume; thermal conductivity; and electrical resistivity; bulk modulus; critical temperature; superconductivity temperature; hardness (mineralogical, Brinell, and Vickers); linear expansion coefficient; Poisson's ratio; reflectivity; refractive index; rigidity modulus; Young's modulus; velocity of sound
- Images
- Reactions of thallium: reactions of thallium with air; water; halogens; acids; and bases
- Crystal structure
- Thermochemistry: enthalpies of atomization, fusion, and vaporization; thermodynamic properties
Atom properties
- Electron shell properties: Electronic configuration; term symbol; electron affinity; ionization energies; and atomic spectra
- Atom sizes: atomic radius; Shannon and Pauling ionic radii; covalent radius; metallic radius; element bond length; and Van der Waals radius
- Atomic orbital properties: effective nuclear charge; electron binding energies; and valence orbital radii maxima
Nuclear properties
- Isotopes: isotope abundances; radioactive isotopes; isotope masses; nuclear spins; and nuclear magnetic moment
- NMR properties: frequencies; isotopes; magnetogyric ratios; quadrupole moments; receptivities; and relative sensitivities

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