Thallium

Thallium ( /ˈθæliəm/ THAL-ee-əm) is a chemical element with the symbol Tl and atomic number 81. This soft gray poor metal resembles tin but discolors when exposed to air. Chemists William Crookes and Claude-Auguste Lamy discovered thallium independently in 1861 by the newly developed method of flame spectroscopy. Each discovered the new element in residues of sulfuric acid production. Approximately 60–70% of thallium production is used in the ele... More

Chemical Element

The 81st Element in the Periodic Table

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Mercury

Mercury is a chemical element with the symbol Hg and atomic number 80. It is also known as quicksilver or hydrargyrum (from "hydr-" water and ...

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Lead

Lead ( /ˈlɛd/) is a main-group element in the carbon group with the symbol Pb (from Latin: plumbum) and atomic number 82. Lead is a soft, malleable...

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Symbol:

  • Tl

Atomic mass:

Mass Uncertainty
  • 204.3833 u (3.393864E-16 µg )
  • 0.0002 u (3.321E-22 µg )

Electron affinity:

Value Uncertainty
  • 0.377 eV (3.77E-7 MeV )
  • 0.013 eV (1.3E-8 MeV )

Electronegativity (Pauling scale):

  • 1.62

Covalent radius:

  • 1.48 pm (5.83E-8 )

Van der Waals radius:

  • 220 pm (0.00000866 )

Melting Point:

  • 303.85 °C (578.94 °F )

Chemical series:

Ionization Energy:

  • 6.1082 eV (0.0000061082 MeV )

Discovery Date:

  • 1861

Discovering Country:

Electron Configuration:

  • Xe 4f14 5d10 6s2 6p1
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