Actinium
Actinium is a chemical element with the symbol Ac and atomic number 89. It was first isolated by Friedrich Oskar Giesel in 1902, who gave it the name ''emanium''; the element got its name by being wrongly identified with a substance And ...
(
89Ac) has no stable
isotope
Isotopes are two or more types of atoms that have the same atomic number (number of protons in their nuclei) and position in the periodic table (and hence belong to the same chemical element), and that differ in nucleon numbers (mass numbers) ...
s and no characteristic terrestrial isotopic composition, thus a
standard atomic weight cannot be given. There are 33 known isotopes, from
204Ac to
236Ac, and 7
isomers
In chemistry, isomers are molecules or polyatomic ions with identical molecular formulae – that is, same number of atoms of each element – but distinct arrangements of atoms in space. Isomerism is existence or possibility of isomers.
Iso ...
. Three isotopes are found in nature,
225Ac,
227Ac and
228Ac, as intermediate decay products of, respectively,
237Np,
235U, and
232Th.
228Ac and
225Ac are extremely rare, so almost all natural actinium is
227Ac.
The most stable isotopes are
227Ac with a half-life of 21.772 years,
225Ac with a half-life of 10.0 days, and
226Ac with a half-life of 29.37 hours. All other isotopes have half-lives under 10 hours, and most under a minute. The shortest-lived known isotope is
217Ac with a half-life of 69
ns.
Purified
227Ac comes into equilibrium with its decay products (
227Th and
223Fr) after 185 days.
[
]
List of isotopes
, -
,
204Ac
,
, style="text-align:right" , 89
, style="text-align:right" , 115
,
,
,
α
,
200Fr
,
,
, -
,
205Ac
,
, style="text-align:right" , 89
, style="text-align:right" , 116
,
,
, α
,
201Fr
, 9/2−?
,
, -
,
206Ac
,
, style="text-align:right" , 89
, style="text-align:right" , 117
, 206.01450(8)
, 25(7) ms
, α
,
202Fr
, (3+)
,
, -
, style="text-indent:1em" ,
206m1Ac
,
, colspan="3" style="text-indent:2em" , 80(50) keV
, 15(6) ms
, α
,
202Fr
,
,
, -
, style="text-indent:1em" ,
206m2Ac
,
, colspan="3" style="text-indent:2em" , 290(110)# keV
, 41(16) ms
, α
,
202mFr
, (10−)
,
, -
,
207Ac
,
, style="text-align:right" , 89
, style="text-align:right" , 118
, 207.01195(6)
, 31(8) ms
7(+11−6) ms, α
,
203Fr
, 9/2−#
,
, -
, rowspan=2,
208Ac
, rowspan=2,
, rowspan=2 style="text-align:right" , 89
, rowspan=2 style="text-align:right" , 119
, rowspan=2, 208.01155(6)
, rowspan=2, 97(16) ms
5(+24−16) ms, α (99%)
,
204Fr
, rowspan=2, (3+)
, rowspan=2,
, -
, β
+ (1%)
,
208Ra
, -
, rowspan=3 style="text-indent:1em" ,
208mAc
, rowspan=3,
, rowspan=3 colspan="3" style="text-indent:2em" , 506(26) keV
, rowspan=3, 28(7) ms
5(+9−5) ms, α (89%)
,
204Fr
, rowspan=3, (10−)
, rowspan=3,
, -
,
IT (10%)
,
208Ac
, -
, β
+ (1%)
,
208Ra
, -
, rowspan=2,
209Ac
, rowspan=2,
, rowspan=2 style="text-align:right" , 89
, rowspan=2 style="text-align:right" , 120
, rowspan=2, 209.00949(5)
, rowspan=2, 92(11) ms
, α (99%)
,
205Fr
, rowspan=2, (9/2−)
, rowspan=2,
, -
, β
+ (1%)
,
209Ra
, -
, rowspan=2,
210Ac
, rowspan=2,
, rowspan=2 style="text-align:right" , 89
, rowspan=2 style="text-align:right" , 121
, rowspan=2, 210.00944(6)
, rowspan=2, 350(40) ms
, α (96%)
,
206Fr
, rowspan=2, 7+#
, rowspan=2,
, -
, β
+ (4%)
,
210Ra
, -
, rowspan=2,
211Ac
, rowspan=2,
, rowspan=2 style="text-align:right" , 89
, rowspan=2 style="text-align:right" , 122
, rowspan=2, 211.00773(8)
, rowspan=2, 213(25) ms
, α (99.8%)
,
207Fr
, rowspan=2, 9/2−#
, rowspan=2,
, -
, β
+ (.2%)
,
211Ra
, -
, rowspan=2,
212Ac
, rowspan=2,
, rowspan=2 style="text-align:right" , 89
, rowspan=2 style="text-align:right" , 123
, rowspan=2, 212.00781(7)
, rowspan=2, 920(50) ms
, α (97%)
,
208Fr
, rowspan=2, 6+#
, rowspan=2,
, -
, β
+ (3%)
,
212Ra
, -
, rowspan=2,
213Ac
, rowspan=2,
, rowspan=2 style="text-align:right" , 89
, rowspan=2 style="text-align:right" , 124
, rowspan=2, 213.00661(6)
, rowspan=2, 731(17) ms
, α
,
209Fr
, rowspan=2, (9/2−)#
, rowspan=2,
, -
, β
+ (rare)
,
213Ra
, -
, rowspan=2,
214Ac
, rowspan=2,
, rowspan=2 style="text-align:right" , 89
, rowspan=2 style="text-align:right" , 125
, rowspan=2, 214.006902(24)
, rowspan=2, 8.2(2) s
, α (89%)
,
210Fr
, rowspan=2, (5+)#
, rowspan=2,
, -
, β
+ (11%)
,
214Ra
, -
, rowspan=2,
215Ac
, rowspan=2,
, rowspan=2 style="text-align:right" , 89
, rowspan=2 style="text-align:right" , 126
, rowspan=2, 215.006454(23)
, rowspan=2, 0.17(1) s
, α (99.91%)
,
211Fr
, rowspan=2, 9/2−
, rowspan=2,
, -
, β
+ (.09%)
,
215Ra
, -
, rowspan=2,
216Ac
, rowspan=2,
, rowspan=2 style="text-align:right" , 89
, rowspan=2 style="text-align:right" , 127
, rowspan=2, 216.008720(29)
, rowspan=2, 0.440(16) ms
, α
,
212Fr
, rowspan=2, (1−)
, rowspan=2,
, -
, β
+ (7×10
−5%)
,
216Ra
, -
, style="text-indent:1em" ,
216mAc
,
, colspan="3" style="text-indent:2em" , 44(7) keV
, 443(7) µs
,
,
, (9−)
,
, -
, rowspan=2,
217Ac
, rowspan=2,
, rowspan=2 style="text-align:right" , 89
, rowspan=2 style="text-align:right" , 128
, rowspan=2, 217.009347(14)
, rowspan=2, 69(4) ns
, α (98%)
,
213Fr
, rowspan=2, 9/2−
, rowspan=2,
, -
, β
+ (6.9×10
−9%)
,
217Ra
, -
, style="text-indent:1em" ,
217mAc
,
, colspan="3" style="text-indent:2em" , 2012(20) keV
, 740(40) ns
,
,
, (29/2)+
,
, -
,
218Ac
,
, style="text-align:right" , 89
, style="text-align:right" , 129
, 218.01164(5)
, 1.08(9) µs
, α
,
214Fr
, (1−)#
,
, -
, style="text-indent:1em" ,
218mAc
,
, colspan="3" style="text-indent:2em" , 584(50)# keV
, 103(11) ns
,
,
, (11+)
,
, -
, rowspan=2,
219Ac
, rowspan=2,
, rowspan=2 style="text-align:right" , 89
, rowspan=2 style="text-align:right" , 130
, rowspan=2, 219.01242(5)
, rowspan=2, 11.8(15) µs
, α
,
215Fr
, rowspan=2, 9/2−
, rowspan=2,
, -
, β
+ (10
−6%)
,
219Ra
, -
, rowspan=2,
220Ac
, rowspan=2,
, rowspan=2 style="text-align:right" , 89
, rowspan=2 style="text-align:right" , 131
, rowspan=2, 220.014763(16)
, rowspan=2, 26.36(19) ms
, α
,
216Fr
, rowspan=2, (3−)
, rowspan=2,
, -
, β
+ (5×10
−4%)
,
220Ra
, -
,
221Ac
,
, style="text-align:right" , 89
, style="text-align:right" , 132
, 221.01559(5)
, 52(2) ms
, α
,
217Fr
, 9/2−#
,
, -
, rowspan=2,
222Ac
, rowspan=2,
, rowspan=2 style="text-align:right" , 89
, rowspan=2 style="text-align:right" , 133
, rowspan=2, 222.017844(6)
, rowspan=2, 5.0(5) s
, α (99%)
,
218Fr
, rowspan=2, 1−
, rowspan=2,
, -
, β
+ (1%)
,
222Ra
, -
, rowspan=3 style="text-indent:1em" ,
222mAc
, rowspan=3,
, rowspan=3 colspan="3" style="text-indent:2em" , 200(150)# keV
, rowspan=3, 1.05(7) min
, α (88.6%)
,
218Fr
, rowspan=3, high
, rowspan=3,
, -
, IT (10%)
,
222Ac
, -
, β
+ (1.4%)
,
222Ra
, -
, rowspan=3,
223Ac
, rowspan=3,
, rowspan=3 style="text-align:right" , 89
, rowspan=3 style="text-align:right" , 134
, rowspan=3, 223.019137(8)
, rowspan=3, 2.10(5) min
, α (99%)
,
219Fr
, rowspan=3, (5/2−)
, rowspan=3,
, -
,
EC (1%)
,
223Ra
, -
,
CD (3.2×10
−9%)
, ''
209Bi''
14C
, -
, rowspan=3,
224Ac
, rowspan=3,
, rowspan=3 style="text-align:right" , 89
, rowspan=3 style="text-align:right" , 135
, rowspan=3, 224.021723(4)
, rowspan=3, 2.78(17) h
, β
+ (90.9%)
,
224Ra
, rowspan=3, 0−
, rowspan=3,
, -
, α (9.1%)
,
220Fr
, -
, β
− (1.6%)
,
224Th
, -
, rowspan=2,
225Ac[Has medical uses]
, rowspan=2,
, rowspan=2 style="text-align:right" , 89
, rowspan=2 style="text-align:right" , 136
, rowspan=2, 225.023230(5)
, rowspan=2, 10.0(1) d
, α
,
221Fr
, rowspan=2, (3/2−)
, rowspan=2, Trace
[Intermediate decay product of 237Np]
, -
, CD (6×10
−10%)
,
211Bi
14C
, -
, rowspan=3,
226Ac
, rowspan=3,
, rowspan=3 style="text-align:right" , 89
, rowspan=3 style="text-align:right" , 137
, rowspan=3, 226.026098(4)
, rowspan=3, 29.37(12) h
, β
− (83%)
,
226Th
, rowspan=3, (1)(−#)
, rowspan=3,
, -
, EC (17%)
,
226Ra
, -
, α (.006%)
,
222Fr
, -
, rowspan=2,
227Ac
, rowspan=2, Actinium
[Source of element's name]
, rowspan=2 style="text-align:right" , 89
, rowspan=2 style="text-align:right" , 138
, rowspan=2, 227.0277521(26)
, rowspan=2, 21.772(3) y
, β
− (98.61%)
,
227Th
, rowspan=2, 3/2−
, rowspan=2, Trace
[Intermediate ]decay product
In nuclear physics, a decay product (also known as a daughter product, daughter isotope, radio-daughter, or daughter nuclide) is the remaining nuclide left over from radioactive decay. Radioactive decay often proceeds via a sequence of steps ( ...
of 235U
, -
, α (1.38%)
,
223Fr
, -
, rowspan=2,
228Ac
, rowspan=2, Mesothorium 2
, rowspan=2 style="text-align:right" , 89
, rowspan=2 style="text-align:right" , 139
, rowspan=2, 228.0310211(27)
, rowspan=2, 6.13(2) h
, β
−
,
228Th
, rowspan=2, 3+
, rowspan=2, Trace
[Intermediate decay product of 232Th]
, -
, α (5.5×10
−6%)
,
224Fr
, -
,
229Ac
,
, style="text-align:right" , 89
, style="text-align:right" , 140
, 229.03302(4)
, 62.7(5) min
, β
−
,
229Th
, (3/2+)
,
, -
,
230Ac
,
, style="text-align:right" , 89
, style="text-align:right" , 141
, 230.03629(32)
, 122(3) s
, β
−
,
230Th
, (1+)
,
, -
,
231Ac
,
, style="text-align:right" , 89
, style="text-align:right" , 142
, 231.03856(11)
, 7.5(1) min
, β
−
,
231Th
, (1/2+)
,
, -
,
232Ac
,
, style="text-align:right" , 89
, style="text-align:right" , 143
, 232.04203(11)
, 119(5) s
, β
−
, ''
232Th''
, (1+)
,
, -
,
233Ac
,
, style="text-align:right" , 89
, style="text-align:right" , 144
, 233.04455(32)#
, 145(10) s
, β
−
,
233Th
, (1/2+)
,
, -
,
234Ac
,
, style="text-align:right" , 89
, style="text-align:right" , 145
, 234.04842(43)#
, 44(7) s
, β
−
,
234Th
,
,
, -
,
235Ac
,
, style="text-align:right" , 89
, style="text-align:right" , 146
, 235.05123(38)#
, 60(4) s
, β
−
,
235Th
, 1/2+#
,
, -
,
236Ac
,
, style="text-align:right" , 89
, style="text-align:right" , 147
, 236.05530(54)#
,
, β
−
,
236Th
,
,
Actinides vs fission products
See also
*
Actinium series
In nuclear science, the decay chain refers to a series of radioactive decays of different radioactive decay products as a sequential series of transformations. It is also known as a "radioactive cascade". Most radioisotopes do not decay directly ...
*
Actinide
The actinide () or actinoid () series encompasses the 15 metallic chemical elements with atomic numbers from 89 to 103, actinium through lawrencium. The actinide series derives its name from the first element in the series, actinium. The inform ...
References
* Isotope masses from:
**
* Isotopic compositions and standard atomic masses from:
**
**
* Half-life, spin, and isomer data selected from the following sources.
**
**
**
{{Authority control
Actinium
Actinium
Actinium is a chemical element with the symbol Ac and atomic number 89. It was first isolated by Friedrich Oskar Giesel in 1902, who gave it the name ''emanium''; the element got its name by being wrongly identified with a substance And ...