General | States | Energies | Oxidation & Electrons |Appearance & Characteristics
Reactions | Other Forms |Radius | Conductivity | Abundance
Encyclopedia Britannica articles


Name Actinium Symbol Ac
atomic number 89 Atomic weight (227)
Density @ 293 K 10.07 g/cm3 Atomic volume 22.54 cm3/mol
Group Trans. Met. discovered 1899


state (s, l, g) s
melting point 1323.2 K boiling point 2743 K
Heat of fusion ? Heat of vaporization ?
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1st ionization energy 499 kJ/mole electronegativity 1.1
2nd ionization energy 1170 kJ/mole electron affinity kJ/mole
3rd ionization energy kJ/mole Specific heat ?
heat atomization 385 kJ/mole atoms

Oxidation & Electrons

Shells 2,8,18,32,18,9,2 electron configuration [Rn] 6d1 7s2
minimum oxidation number 0 maximum oxidation number 3
min. common oxidation no. 0 max. common oxidation no. 3
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Appearance & Characteristics

structure fcc: face-centered cubic color silvery-white
uses thermoelectric power toxicity
hardness mohs characteristics Radioactive


reaction with air mild, w/ht, = Ac2O3 reaction with 6M HCl mild, = H2, AcCl3
reaction with 6M HCl mild, = H2, AcCl3 reaction with 15M HNO3 mild, = Ac(NO3)3
reaction with 6M NaOH
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Other Forms

number of isotopes 2 hydride(s) AcH2
oxide(s) Ac2O3 chloride(s) AcCl3


ionic radius (2- ion) pm ionic radius (1- ion) pm
atomic radius pm ionic radius (1+ ion) pm
ionic radius (2+ ion) pm ionic radius (3+ ion) 126 pm
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thermal conductivity J/m-sec-deg electrical conductivity 1/mohm-cm
polarizability 32.1 A^3


source Synthetic(U-235 decay) rel. abund. solar system log
abundance earth's crust -9.3 log cost, pure $/100g
cost, bulk $/100g
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World Wide Web presentation of Chemicool Periodic Table is © Copyright 1996-99 by David D. Hsu. Some data were provided by and used with the permission of JCE Software and is owned and copyright by the Division of Chemical Education, Inc. Additional data were provided by Perkin-Elmer through Peter Lykos of IIT. The information may not be redistributed without the permission of David Hsu or JCE Software.