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Ba
56
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57
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58
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88
Ac
89
Th
90
 
 
 

 

Periodic table

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Actinium

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Actinium

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Actinium

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Aktinij

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Attinio

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Actinio

 

Ac
Ac
Actinium

PERIODIC TABLE OF THE ELEMENTS

ACTINIUM

TRANSITION ELEMENT: SCANDIUM GROUP

 

Atomic number:89

Group numbers:3

Period:7

Electronic configuration:[Rn] 6d1 7s2

Formal oxidation number:+3

Electronegativities:1.1

Atomic radius / pm:188

Relative atomic mass:[227]

 

Actinium was discovered by André-Louis Debierne (FR) in 1899. The origin of the name comes from the Greek word aktinos meaning ray. It is a heavy, silvery-white, very radioactive metal that reacts with water and glows in the dark. Actinium is extremely rare, found in all uranium ores. It's usually obtained by treating radium with neutrons in a reactor.

PHYSICAL PROPERTIES

Density / g dm-3:10060 (calc.)

Molar volume / cm3mol-1:22.56 (calc.)

Electrical resistivity / μΩcm:- (20 °C)

THERMAL PROPERTIES

Thermal conductivity / W m-1K-1:12

Melting point / °C:1051

Boiling point / °C:3198

Heat of fusion / kJ mol-1:-

Heat of vaporization / kJ mol-1:-

Heat of atomization / kJ mol-1:406

IONIZATION ENERGIES

First ionization energy / kJ mol-1:498.83

Second ionization energy / kJ mol-1:1167.48

Third ionization energy / kJ mol-1:-

ABUNDANCE OF ELEMENTS

in the atmosphere / ppm:-

in the Earth's crust / ppm:-

in the oceans / ppm:-

CRYSTALLOGRAPHIC DATA

face-centered cubic

Crystal structure:

face-centered cubic

Unit-cell dimensions / pm:

a=531.1

Space group:

Fm3m

ISOTOPES

IsotopeRelative atomic massMass percent (%)
227Ac227.027747(3)*

REDUCTION POTENTIALS

Balanced half-reaction Eo / V

 

88 Radium <=
89 Actinium
=> 90 Thorium