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Information valid for Er-167 unless otherwise noted

Basic Information

Symbol: Er
Atomic Number: 68
Mass: 167.26
Melting Point: 1522.0 C
Boiling Point: 2510.0 C
Number of Protons/Electrons: 68
Number of Neutrons: 99
Classification: Rare Earth
Crystal Structure: Hexagonal
Density @ 293 K: 8.795 g/cm3
Color: grayish

Atomic Structure

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

  1. First Energy Level: 2
    Second Energy Level: 8
    Third Energy Level: 18
    Fourth Energy Level: 30
    Fifth Energy Level: 8
    Sixth Energy Level: 2


Isotope Half Life
Er-162 Stable
Er-164 Stable
Er-166 Stable
Er-167 Stable
Er-168 Stable
Er-169 9.4 days
Er-170 Stable
Er-171 7.5 hours
Er-172 2.1 days


Date of Discovery: 1843
Discoverer: Carl Mosander
Name Origin: Ytterby (a town in Sweden)
Uses: ceramics
Obtained From: heavier rare earth minerals