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Information valid for Tb-159 unless otherwise noted

Basic Information

Symbol: Tb
Atomic Number: 65
Mass: 158.92534
Melting Point: 1360.0 C
Boiling Point: 3041.0 C
Number of Protons/Electrons: 65
Number of Neutrons: 94
Classification: Rare Earth
Crystal Structure: Hexagonal
Density @ 293 K: 8.27 g/cm3
Color: silverish

Atomic Structure

[Bohr Model of Terbium]
Number of Energy Levels: 6

  1. First Energy Level: 2
    Second Energy Level: 8
    Third Energy Level: 18
    Fourth Energy Level: 27
    Fifth Energy Level: 8
    Sixth Energy Level: 2


Isotope Half Life
Tb-151 17.61 hours
Tb-155 5.3 days
Tb-156 5.3 days
Tb-157 110.0 years
Tb-158 180.0 years
Tb-159 Stable
Tb-160 72.3 days
Tb-161 6.91 days
Tb-162 7.6 minutes


Date of Discovery: 1843
Discoverer: Carl Mosander
Name Origin: Ytterby (a town in Sweden)
Uses: in color TV's
Obtained From: with other rare earths