Actinium

Actinium (Ac)

Actinium is the 89th element in the periodic table and has a symbol of Ac and atomic number of 89. It has an atomic weight of (227) and a mass number of 205. Actinium has eighty-nine protons and one hundred sixteen neutrons in its nucleus, and eighty-nine electrons in seven shells. It is located in group three, period seven and block d of the periodic table. Silvery radioactive metallic element, belongs to group 3 of the periodic table. The most stable isotope, Ac-227, has a half-life of 217 years. Ac-228 (half-life of 6.13 hours) also occurs in nature. There are 22 other artificial isotopes, all radioactive and having very short half-lives. Chemistry similar to lanthanumpy. Used as a source of alpha particles. Discovered by A. Debierne in 1899.
Atomic Number89
Atomic Weight227
Mass Number205
Group3
Period7
Blockd
Protons89 p+
Neutrons116 n0
Electrons89 e-
Animated Bohr Model of Ac (Actinium)

Physical Properties

Atomic Radius
195 pm
Molar Volume
22.54 cm³/mol
Covalent Radius
186 pm
Metallic Radius
Ionic Radius
112 pm
Crystal Radius
126 pm
Van der Waals Radius
247 pm
Density
Atomic Radii of the Elements: Actinium0255075100125150175200225250pmAtomic RadiusCovalent RadiusMetallic RadiusVan der Waals Radius

Chemical Properties

Energy
Proton Affinity
Electron Affinity
Ionization Energy
5.380226 eV/particle
Ionization Energies of Ac (Actinium)
Heat of Vaporization
292.9 kJ/mol
Heat of Fusion
10.5 kJ/mol
Heat of Formation
406 kJ/mol
Electrons
Electron Shells2, 8, 18, 32, 18, 9, 2
Bohr Model: Ac (Actinium)
Valence Electrons2
Lewis Structure: Ac (Actinium)
Electron Configuration[Rn] 6d1 7s2
1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14 5d10 6p6 6d1 7s2
Enhanced Bohr Model of Ac (Actinium)
Orbital Diagram of Ac (Actinium)
Oxidation States2, 3
Electronegativity
1.1
Electrophilicity Index
0.8159546412794374 eV/particle
States of Matter
PhaseSolid
Gas Phase
Boiling Point
3,473.15 K
Melting Point
1,323.15 K
Critical Pressure
Critical Temperature
Triple Point
Visual

Actinium is a Silver. Ac has a CPK of #ffffff, Jmol of #70abfa, and MOLCAS GV of #70abfa.

Color
Silver
Appearance
Refractive Index
Thermodynamic Properties
Thermal Conductivity
Thermal Expansion
Molar Heat Capacity
Specific Heat Capacity
Heat Capacity Ratio (Adiabatic Index)
Electrical Properties
Type
Electrical Conductivity
Electrical Resistivity
Superconducting Point
Magnetism
Type
Magnetic Susceptibility (Mass)
Magnetic Susceptibility (Molar)
Magnetic Susceptibility (Volume)
Magnetic Ordering
Curie Point
Neel Point
Structure

The Crystal Structure of Actinium is FCC. The lattice constant of Ac is 5.31 Å. The lattice angles of Element 89 are π/2, π/2, π/2.

Crystal StructureFace Centered Cubic (FCC)
Lattice Constant
5.31 Å
Lattice Anglesπ/2, π/2, π/2
Mechanical Properties
Hardness
Bulk Modulus
Shear Modulus
Young's Modulus
Poisson Ratio
Speed of Sound
Classification

The CAS Group of Actinium is IIIA. The IUPAC Group of Ac is IIIB. The Glawe Number of Element 89 is 33. The Mendeleev Number of Actinium (Ac) is 14. The Pettifor Number of Actinium is 48. The Geochemical Class of Ac is U/Th decay series. The Goldschmidt Class of Element 89 is synthetic.

CategoryActinides, Actinides
CAS GroupIIIA
IUPAC GroupIIIB
Glawe Number33
Mendeleev Number14
Pettifor Number48
Geochemical ClassU/Th decay series
Goldschmidt Classsynthetic

Other

The Dipole Polarizability of Actinium is 203 plus or minus 12 a₀. The Allotropes of Ac is . The Neutron Cross Section of Element 89 is 880. The Neutron Mass Absorption of Actinium (Ac) is 0.078. The Quantum Numbers of Actinium is 2D3/2. The Space Group of Ac is 225 (Fm_3m).

Gas Basicity
Dipole Polarizability
203 ± 12 a₀
C6 Dispersion Coefficient
Allotropes
Neutron Cross Section
880
Neutron Mass Absorption
0.078
Quantum Numbers2D3/2
Space Group225 (Fm_3m)

Isotopes of Actinium

Stable Isotopes0
Unstable Isotopes33
Natural Isotopes0

205Ac

Mass Number205
Neutron Number116
Relative Atomic Mass
205.015144152 ± 0.000063682 Da
G-Factor
Abundance
Radioactivity☢️ Radioactive
Half Life
80 ± 60 ms
Spin9/2
Quadrupole Moment
Discovery Year2014
Parity-

Decay ModeIntensity
α (α emission)100%
β+ (β+ decay; β+ = ϵ + e+)

206Ac

Mass Number206
Neutron Number117
Relative Atomic Mass
206.014476477 ± 0.000069874 Da
G-Factor
Abundance
Radioactivity☢️ Radioactive
Half Life
25 ± 7 ms
Spin3
Quadrupole Moment
Discovery Year1998
Parity+

Decay ModeIntensity
α (α emission)100%
β+ (β+ decay; β+ = ϵ + e+)

207Ac

Mass Number207
Neutron Number118
Relative Atomic Mass
207.011965967 ± 0.000060384 Da
G-Factor
Abundance
Radioactivity☢️ Radioactive
Half Life
31 ± 8 ms
Spin9/2
Quadrupole Moment
Discovery Year1994
Parity-

Decay ModeIntensity
α (α emission)100%

208Ac

Mass Number208
Neutron Number119
Relative Atomic Mass
208.011552251 ± 0.000069225 Da
G-Factor
Abundance
Radioactivity☢️ Radioactive
Half Life
97 ± 15 ms
Spin3
Quadrupole Moment
Discovery Year1994
Parity+

Decay ModeIntensity
α (α emission)100%
β+ (β+ decay; β+ = ϵ + e+)

209Ac

Mass Number209
Neutron Number120
Relative Atomic Mass
209.009495375 ± 0.000059953 Da
G-Factor
Abundance
Radioactivity☢️ Radioactive
Half Life
94 ± 10 ms
Spin9/2
Quadrupole Moment
Discovery Year1968
Parity-

Decay ModeIntensity
α (α emission)100%
β+ (β+ decay; β+ = ϵ + e+)

210Ac

Mass Number210
Neutron Number121
Relative Atomic Mass
210.009408625 ± 0.000066782 Da
G-Factor
Abundance
Radioactivity☢️ Radioactive
Half Life
350 ± 40 ms
Spin7
Quadrupole Moment
Discovery Year1968
Parity+

Decay ModeIntensity
α (α emission)100%
β+ (β+ decay; β+ = ϵ + e+)

211Ac

Mass Number211
Neutron Number122
Relative Atomic Mass
211.007668846 ± 0.000057706 Da
G-Factor
Abundance
Radioactivity☢️ Radioactive
Half Life
213 ± 25 ms
Spin9/2
Quadrupole Moment
Discovery Year1968
Parity-

Decay ModeIntensity
α (α emission)100%
β+ (β+ decay; β+ = ϵ + e+)

212Ac

Mass Number212
Neutron Number123
Relative Atomic Mass
212.007836442 ± 0.000023492 Da
G-Factor
Abundance
Radioactivity☢️ Radioactive
Half Life
895 ± 28 ms
Spin7
Quadrupole Moment
Discovery Year1968
Parity+

Decay ModeIntensity
α (α emission)100%
β+ (β+ decay; β+ = ϵ + e+)

213Ac

Mass Number213
Neutron Number124
Relative Atomic Mass
213.006592665 ± 0.000012522 Da
G-Factor
Abundance
Radioactivity☢️ Radioactive
Half Life
738 ± 16 ms
Spin9/2
Quadrupole Moment
Discovery Year1968
Parity-

Decay ModeIntensity
α (α emission)100%
β+ (β+ decay; β+ = ϵ + e+)

214Ac

Mass Number214
Neutron Number125
Relative Atomic Mass
214.0069064 ± 0.000014547 Da
G-Factor
Abundance
Radioactivity☢️ Radioactive
Half Life
8.2 ± 0.2 s
Spin5
Quadrupole Moment
Discovery Year1968
Parity+

Decay ModeIntensity
α (α emission)93%
β+ (β+ decay; β+ = ϵ + e+)7%

215Ac

Mass Number215
Neutron Number126
Relative Atomic Mass
215.006474061 ± 0.000013318 Da
G-Factor
Abundance
Radioactivity☢️ Radioactive
Half Life
171 ± 10 ms
Spin9/2
Quadrupole Moment
Discovery Year1968
Parity-

Decay ModeIntensity
α (α emission)100%
β+ (β+ decay; β+ = ϵ + e+)0.09%

216Ac

Mass Number216
Neutron Number127
Relative Atomic Mass
216.008749101 ± 0.000009908 Da
G-Factor
Abundance
Radioactivity☢️ Radioactive
Half Life
440 ± 16 us
Spin1
Quadrupole Moment
Discovery Year1967
Parity-

Decay ModeIntensity
α (α emission)100%
β+ (β+ decay; β+ = ϵ + e+)

217Ac

Mass Number217
Neutron Number128
Relative Atomic Mass
217.009342325 ± 0.000012048 Da
G-Factor
0.85111111111111 ± 0.011111111111111
Abundance
Radioactivity☢️ Radioactive
Half Life
69 ± 4 ns
Spin9/2
Quadrupole Moment
Discovery Year1972
Parity-

Decay ModeIntensity
α (α emission)100%
β+ (β+ decay; β+ = ϵ + e+)

218Ac

Mass Number218
Neutron Number129
Relative Atomic Mass
218.01164886 ± 0.000061853 Da
G-Factor
Abundance
Radioactivity☢️ Radioactive
Half Life
1 ± 0.04 us
Spin1
Quadrupole Moment
Discovery Year1970
Parity-

Decay ModeIntensity
α (α emission)100%

219Ac

Mass Number219
Neutron Number130
Relative Atomic Mass
219.012420425 ± 0.000055263 Da
G-Factor
Abundance
Radioactivity☢️ Radioactive
Half Life
9.4 ± 1 us
Spin9/2
Quadrupole Moment
Discovery Year1970
Parity-

Decay ModeIntensity
α (α emission)100%
β+ (β+ decay; β+ = ϵ + e+)

220Ac

Mass Number220
Neutron Number131
Relative Atomic Mass
220.014754527 ± 0.000006579 Da
G-Factor
Abundance
Radioactivity☢️ Radioactive
Half Life
26.36 ± 0.19 ms
Spin3
Quadrupole Moment
Discovery Year1970
Parity-

Decay ModeIntensity
α (α emission)100%
β+ (β+ decay; β+ = ϵ + e+)

221Ac

Mass Number221
Neutron Number132
Relative Atomic Mass
221.015599721 ± 0.000061086 Da
G-Factor
Abundance
Radioactivity☢️ Radioactive
Half Life
52 ± 2 ms
Spin9/2
Quadrupole Moment
Discovery Year1968
Parity-

Decay ModeIntensity
α (α emission)100%

222Ac

Mass Number222
Neutron Number133
Relative Atomic Mass
222.017844232 ± 0.000005044 Da
G-Factor
Abundance
Radioactivity☢️ Radioactive
Half Life
5 ± 0.5 s
Spin1
Quadrupole Moment
Discovery Year1949
Parity-

Decay ModeIntensity
α (α emission)99%
β+ (β+ decay; β+ = ϵ + e+)1%

223Ac

Mass Number223
Neutron Number134
Relative Atomic Mass
223.019135982 ± 0.000007457 Da
G-Factor
Abundance
Radioactivity☢️ Radioactive
Half Life
2.1 ± 0.05 m
Spin5/2
Quadrupole Moment
Discovery Year1948
Parity-

Decay ModeIntensity
α (α emission)99%
ϵ (electron capture)

224Ac

Mass Number224
Neutron Number135
Relative Atomic Mass
224.021722249 ± 0.000004389 Da
G-Factor
0
Abundance
Radioactivity☢️ Radioactive
Half Life
2.78 ± 0.16 h
Spin0
Quadrupole Moment
0
Discovery Year1948
Parity-

Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)90.5%
α (α emission)9.5%
β (β decay)

225Ac

Mass Number225
Neutron Number136
Relative Atomic Mass
225.023228601 ± 0.000005107 Da
G-Factor
Abundance
Radioactivity☢️ Radioactive
Half Life
9.919 ± 0.0021 d
Spin3/2
Quadrupole Moment
Discovery Year1947
Parity-

Decay ModeIntensity
α (α emission)100%
14C5.3%

226Ac

Mass Number226
Neutron Number137
Relative Atomic Mass
226.026096999 ± 0.000003327 Da
G-Factor
Abundance
Radioactivity☢️ Radioactive
Half Life
29.37 ± 0.12 h
Spin1
Quadrupole Moment
Discovery Year1950
Parity-

Decay ModeIntensity
β (β decay)83%
ϵ (electron capture)17%
α (α emission)0.006%

227Ac

Mass Number227
Neutron Number138
Relative Atomic Mass
227.027750594 ± 0.000002068 Da
G-Factor
Abundance
Radioactivity☢️ Radioactive
Half Life
21.772 ± 0.003 y
Spin3/2
Quadrupole Moment
Discovery Year1851
Parity-

Decay ModeIntensity
β (β decay)98.62%
α (α emission)1.38%

228Ac

Mass Number228
Neutron Number139
Relative Atomic Mass
228.031019685 ± 0.000002247 Da
G-Factor
Abundance
Radioactivity☢️ Radioactive
Half Life
6.15 ± 0.02 h
Spin3
Quadrupole Moment
Discovery Year1908
Parity+

Decay ModeIntensity
β (β decay)100%

229Ac

Mass Number229
Neutron Number140
Relative Atomic Mass
229.032947 ± 0.000013 Da
G-Factor
Abundance
Radioactivity☢️ Radioactive
Half Life
62.7 ± 0.5 m
Spin3/2
Quadrupole Moment
Discovery Year1952
Parity+

Decay ModeIntensity
β (β decay)100%

230Ac

Mass Number230
Neutron Number141
Relative Atomic Mass
230.036327 ± 0.000017 Da
G-Factor
Abundance
Radioactivity☢️ Radioactive
Half Life
122 ± 3 s
Spin1
Quadrupole Moment
Discovery Year1973
Parity+

Decay ModeIntensity
β (β decay)100%
β SF (β-delayed fission)1.2%

231Ac

Mass Number231
Neutron Number142
Relative Atomic Mass
231.038393 ± 0.000014 Da
G-Factor
Abundance
Radioactivity☢️ Radioactive
Half Life
7.5 ± 0.1 m
Spin1/2
Quadrupole Moment
0
Discovery Year1973
Parity+

Decay ModeIntensity
β (β decay)100%

232Ac

Mass Number232
Neutron Number143
Relative Atomic Mass
232.042034 ± 0.000014 Da
G-Factor
Abundance
Radioactivity☢️ Radioactive
Half Life
1.98 ± 0.08 m
Spin1
Quadrupole Moment
Discovery Year1986
Parity+

Decay ModeIntensity
β (β decay)100%

233Ac

Mass Number233
Neutron Number144
Relative Atomic Mass
233.044346 ± 0.000014 Da
G-Factor
Abundance
Radioactivity☢️ Radioactive
Half Life
143 ± 10 s
Spin1/2
Quadrupole Moment
0
Discovery Year1983
Parity+

Decay ModeIntensity
β (β decay)100%

234Ac

Mass Number234
Neutron Number145
Relative Atomic Mass
234.048139 ± 0.000015 Da
G-Factor
Abundance
Radioactivity☢️ Radioactive
Half Life
45 ± 2 s
Spin1
Quadrupole Moment
Discovery Year1986
Parity+

Decay ModeIntensity
β (β decay)100%

235Ac

Mass Number235
Neutron Number146
Relative Atomic Mass
235.05084 ± 0.000015 Da
G-Factor
Abundance
Radioactivity☢️ Radioactive
Half Life
62 ± 4 s
Spin1/2
Quadrupole Moment
0
Discovery Year2006
Parity+

Decay ModeIntensity
β (β decay)100%

236Ac

Mass Number236
Neutron Number147
Relative Atomic Mass
236.054988 ± 0.000041 Da
G-Factor
Abundance
Radioactivity☢️ Radioactive
Half Life
4.5 ± 3.6 m
Spin3
Quadrupole Moment
Discovery Year2010
Parity+

Decay ModeIntensity
β (β decay)100%

237Ac

Mass Number237
Neutron Number148
Relative Atomic Mass
237.057993 ± 0.000429 Da
G-Factor
Abundance
Radioactivity☢️ Radioactive
Half Life
Spin1/2
Quadrupole Moment
0
Discovery Year
Parity+

Decay ModeIntensity
β (β decay)
Actinium sample (31481701837)
Electron shell 089 Actinium

History

André-Louis Debierne, a French chemist, discovered actinium in 1899. He separated it from pitchblende residues left by Marie and Pierre Curie after they had extracted radium. Friedrich Oskar Giesel independently discovered actinium in 1902 as a substance being similar to lanthanum. From the Greek aktis, aktinos, meaning beam or ray

DiscoverersAndré Debierne
Discovery LocationFrance
Discovery Year1899
Etymology (Name Origin)Greek: akis, aktinos (ray).
Pronunciationak-TIN-i-em (English)
Actinium is highly radioactive
Actinium glows in the dark with a pale blue light

Uses

Actinium is used as an active element of radioisotope thermoelectric generators, for example in spacecraft. The medium half-life of 227Ac makes it very convenient radioactive isotope in modeling the slow vertical mixing of oceanic waters. 225Ac is applied in medicine to produce 213Bi in a reusable generator or can be used alone as an agent for radiation therapy. It has no significant commercial applications.

Sources

Extremely rare, found in all uranium ores. Usually obtained by treating radium with neutrons in a reactor.

Abundance
Abundance in Earth's crust
0.00000000055 mg/kg
Natural Abundance (Oceans)
Natural Abundance (Human Body)
0 %
Natural Abundance (Meteor)
Natural Abundance (Sun)
0 %
Abundance in Universe
0 %

Nuclear Screening Constants

Also Known As

  • Ac
  • element 89
  • emanium
  • 89Ac

Translations

  • Frenchactinium
  • Italianattinio
  • Norwegian Bokmålactinium
  • GermanActinium
  • Spanishactinio
  • Dutchactinium
  • Norwegian Nynorskactinium
  • Danishactinium
  • Swedishaktinium
  • Portugueseactínio
  • Afrikaansaktinium
  • Amharicአክቲኒየም
  • Arabicأكتينيوم
  • AsturianActiniu
  • AzerbaijaniAktinium
  • Belarusianактыній
  • Bulgarianактиний
  • Banglaঅ্যাক্টিনিয়াম
  • Bosnianaktinij
  • Catalanactini
  • CorsicanAttiniu
  • Czechaktinium
  • ChuvashАктини
  • WelshActiniwm
  • Greekακτίνιο
  • Esperantoaktinio
  • Estonianaktiinium
  • Basqueaktinio
  • Persianاکتینیم
  • Finnishaktinium
  • FriulianAtini
  • Irishachtainiam
  • Galicianactinio
  • Manxaghtinnium
  • Hebrewאקטיניום
  • Hindiऐक्टिनियम
  • Fiji HindiActinium
  • Croatianaktinij
  • Haitian CreoleAktiniòm
  • Hungarianaktínium
  • Armenianակտինիում
  • Interlinguaactinium
  • Indonesianaktinium
  • Idoaktiniumo
  • Japaneseアクチニウム
  • Lojbanjinmrtaktini
  • JavaneseAktinium
  • KazakhАктиний
  • Korean악티늄
  • KomiАктиний
  • Latinactinium
  • LuxembourgishActinium
  • LigurianAttinio
  • Lithuanianaktinis
  • Latvianaktīnijs
  • Malayalamആക്റ്റിനിയം
  • Mongolianактини
  • Marathiअॅक्टिनियम
  • Western MariАктиний
  • MalayAktinium
  • Burmeseအက်တီနီယမ်
  • Low GermanActinium
  • Newariएक्टिनियम
  • Occitanactini
  • Polishaktyn
  • Western Panjabiایکٹینیم
  • QuechuaAktinyu
  • Romanianactiniu
  • Russianактиний
  • RusynАктіній
  • YakutАктиниум
  • Sicilianattiniu
  • Serbo-CroatianAktinijum
  • Slovakaktínium
  • Slovenianaktinij
  • Albanianaktiniumi
  • Serbianактинијум
  • Saterland FrisianAktinium
  • Tamilஅக்டினியம்
  • Thaiแอกทิเนียม
  • TagalogAktinyo
  • Turkishaktinyum
  • Uyghurئاكتىنىي
  • Ukrainianактиній
  • Urduعیکٹنیئم
  • VepsAktinii
  • Vietnameseactini
  • WarayActinyo
  • KalmykАктиниум
  • YorubaÀktíníọ̀m
  • Chinese
  • Georgianაქტინიუმი
  • CebuanoActinyo
  • BretonAktiniom
  • Central Kurdishئەکتینیۆم
  • Odiaଆକ୍ଟିନିଅମ
  • Gujaratiએક્ટિનીયમ
  • Macedonianактиниум
  • PiedmonteseActini
  • TatarАктиний
  • Kannadaಆಕ್ಟಿನಿಯಮ್
  • Cantonese
  • SomaliAktiiniyaam
  • Belarusian (Taraskievica orthography)актын
  • UzbekAktiniy
  • Chinese (China)
  • Chinese (Simplified)
  • Chinese (Traditional)
  • Chinese (Hong Kong SAR China)
  • Chinese (Taiwan)
  • AromanianActiniu
  • KyrgyzАктиний
  • LimburgishActinium
  • Teluguఅక్టీనియం
  • Sanskritएक्टिनियम
  • Malteseaktinju
  • Scottish GaelicActinium
  • Nepaliएक्टिनियम
  • Paliएक्टिनियम
  • Hakka Chineseactinium
  • cdoActinium
  • Min Nan ChineseActinium
  • Bhojpuriएक्टिनियम
  • Tibetanཨེག་ཊི་ནིམ།
  • Portuguese (Brazil)actínio
  • Literary Chinese
  • TajikАктиний
  • kbpAkɩtɩnɩyɔm
  • Lingua Franca Novaactinio
  • Northern FrisianAktiinium
  • oloAktiinii
  • Volapüklaktinin
  • Wu Chinese
  • SwahiliAktini
  • SardinianAtìniu
  • Moroccan Arabicآكتينيوم
  • Northern SamiAktinium
  • Egyptian Arabicاكتينيوم
  • Pashtoآکټېنيوم
  • CornishAktiniom
  • BalineseAktinium
  • BikolAktinyo
  • ZuluIsAcagu