Actinium at Chemical Elements.com 


 

Basic Information


Name: Actinium
Symbol: Ac
Atomic Number: 89
Atomic Mass: (227.0) amu
Melting Point: 1050.0 °C (1323.15 °K, 1922.0 °F)
Boiling Point: 3200.0 °C (3473.15 °K, 5792.0 °F)
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

[Bohr Model of Actinium]  
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: 9
    Seventh Energy Level: 2

Isotopes

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

Facts


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