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Thorium at Chemical Elements.com
Basic Information | Atomic Structure | Isotopes | Related Links | Citing This Page

Basic Information

Name: Thorium
Symbol: Th
Atomic Number: 90
Atomic Mass: 232.0381 amu
Melting Point: 1750.0 °C (2023.15 K, 3182.0 °F)
Boiling Point: 4790.0 °C (5063.15 K, 8654.0 °F)
Number of Protons/Electrons: 90
Number of Neutrons: 142
Classification: Rare Earth
Crystal Structure: Cubic
Density @ 293 K: 11.72 g/cm3
Color: silvery

Atomic Structure

[Bohr Model of Thorium]  
Number of Energy Levels: 7

    First Energy Level: 2
    Second Energy Level: 8
    Third Energy Level: 18
    Fourth Energy Level: 32
    Fifth Energy Level: 18
    Sixth Energy Level: 10
    Seventh Energy Level: 2


Isotope Half Life
Th-22630.6 minutes
Th-22718.72 days
Th-2281.91 years
Th-2297340.0 years
Th-23075400.0 years
Th-2311.06 days
Th-2321.4E10 years
Th-23322.3 minutes
Th-23424.1 days


Date of Discovery: 1828
Discoverer: Jons Berzelius
Name Origin: Thor (Scandinavian god)
Uses: strong alloys, ultraviolet photoelectric cells
Obtained From: monazite, thorite

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