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Information valid for Ac-227 unless otherwise noted

Basic Information

Symbol: Ac
Atomic Number: 89
Mass: (227.0)
Melting Point: 1050.0 C
Boiling Point: 3200.0 C
Number of Protons/Electrons: 89
Number of Neutrons: 138
Classification: Rare Earth
Crystal Structure: Cubic
Density @ 293 K: 10.07 g/cm3
Color: Silvery

Atomic Structure

b0089.gif (32259 bytes)
Number of Energy Levels: 7

  1. First Energy Level: 2
    Second Energy Level: 8
    Third Energy Level: 18
    Fourth Energy Level: 32
    Fifth Energy Level: 18
    Sixth Energy Level: 9
    Seventh Energy Level: 2


Isotope Half Life
Ac-225 10.0 days
Ac-226 1.2 days
Ac-227 21.8 years
Ac-228 6.16 hours


Date of Discovery: 1899
Discoverer: Andre Debierne
Name Origin: From the Greek word aktinos (ray)
Uses: No uses known
Obtained From: extremely rare