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Nuclides with atomic number of 99 but with different mass numbers
Einsteinium
(
99
Es) is a
synthetic element
, and thus a
standard atomic weight
cannot be given. Like all synthetic elements, it has no
stable isotopes
. The first
isotope
to be discovered (in nuclear
fallout
from the
Ivy Mike
H-bomb
test
) was
253
Es in 1952. There are 18 known
radioisotopes
from
240
Es to
257
Es, and 5
nuclear isomers
. The longest-lived isotope is
252
Es with a
half-life
of 471.7 days, or around 1.293 years.
List of isotopes
[
edit
]
Nuclide
[n 1]
|
Z
|
N
|
Isotopic mass
(
Da
)
[2]
[n 2]
[n 3]
|
Half-life
[1]
|
Decay
mode
[1]
[n 4]
|
Daughter
isotope
|
Spin
and
parity
[1]
[n 5]
[n 6]
|
Excitation energy
[n 6]
|
240
Es
|
99
|
141
|
240.06895(39)#
|
6.0(17) s
|
α
(70%)
|
236
Bk
|
4?#
|
β
+
(30%)
|
240
Cf
|
β
+
,
SF
(0.16%)
|
(various)
|
241
Es
[3]
|
99
|
142
|
241.06859(25)#
|
4.3
+2.4
?1.2
s
|
α
|
237
Bk
|
3/2?#
|
β
+
?
|
241
Cf
|
242
Es
[4]
|
99
|
143
|
242.06957(28)#
|
16.9(8) s
|
β
+
|
242
Cf
|
2+#
|
α (41%)
|
238
Bk
|
β
+
, SF (1.5%)
|
(various)
|
243
Es
|
99
|
144
|
243.06951(22)#
|
22.1(14) s
|
α (61%)
|
239
Bk
|
(7/2+)
|
β
+
(39%)
|
243
Cf
|
244
Es
|
99
|
145
|
244.07088(20)#
|
37(4) s
|
β
+
(95%)
|
244
Cf
|
6+#
|
α (5%)
|
240
Bk
|
β
+
, SF (0.011%)
|
(various)
|
245
Es
|
99
|
146
|
245.07119(18)#
|
1.11(6) min
|
β
+
(51%)
|
245
Cf
|
(3/2?)
|
α (49%)
|
241
Bk
|
245m1
Es
|
30(15)# keV
|
>50# us
|
IT
?
|
245
Es
|
7/2+#
|
α?
|
241
Bk
|
β
+
?
|
245
Cf
|
245m2
Es
|
283(15)# keV
|
|
IT
|
245
Es
|
(7/2?)
|
246
Es
|
99
|
147
|
246.072806(97)
|
7.5(5) min
|
β
+
(90.1%)
|
246
Cf
|
4?#
|
α (9.9%)
|
242
Bk
|
β
+
, SF (.003%)
|
(various)
|
247
Es
|
99
|
148
|
247.073622(21)
|
4.55(26) min
|
β
+
(93%)
|
247
Cf
|
(7/2+)
|
α (7%)
|
243
Bk
|
SF?
|
(various)
|
248
Es
|
99
|
149
|
248.075469(56)#
|
24(3) min
|
β
+
(99.75%)
|
248
Cf
|
2?#
|
α (.25%)
|
244
Bk
|
β
+
, SF (3.5×10
?4
%)
|
(various)
|
249
Es
|
99
|
150
|
249.076409(32)#
|
102.2(6) min
|
β
+
(99.43%)
|
249
Cf
|
7/2+
|
α (.57%)
|
245
Bk
|
250
Es
|
99
|
151
|
250.07861(11)#
|
8.6(1) h
|
β
+
|
250
Cf
|
6(+)
|
α?
|
246
Bk
|
250m
Es
|
200(150)# keV
|
2.22(5) h
|
β
+
|
250
Cf
|
1(?)
|
α?
|
246
Bk
|
251
Es
|
99
|
152
|
251.0799914(57)
|
33(1) h
|
EC
(99.5%)
|
251
Cf
|
3/2?
|
α (.5%)
|
247
Bk
|
252
Es
|
99
|
153
|
252.082979(54)
|
471.7(19) d
|
α (78(2)%)
|
248
Bk
|
(4+)
|
EC (22(2)%)
|
252
Cf
|
253
Es
[n 7]
|
99
|
154
|
253.0848212(13)
|
20.47(3) d
|
α
|
249
Bk
|
7/2+
|
SF (8.7×10
?6
%)
|
(various)
|
254
Es
|
99
|
155
|
254.0880243(32)
|
275.7(5) d
|
α
[n 8]
|
250
Bk
|
7+
|
β
?
(1.74×10
?4
%)
|
254
Fm
|
SF (<3×10
?6
%)
|
(various)
|
254m
Es
|
80.4(11) keV
|
39.3(2) h
|
β
?
(98(2)%)
|
254
Fm
|
2+
|
IT (<3%)
|
254
Es
|
α (0.32(1)%)
|
250
Bk
|
EC (0.076(7)%)
|
254
Cf
|
SF (<0.045%)
|
(various)
|
255
Es
|
99
|
156
|
255.090274(12)
|
39.8(12) d
|
β
?
(92.0%)
|
255
Fm
|
(7/2+)
|
α (8.0%)
|
251
Bk
|
SF (.0041%)
|
(various)
|
256
Es
|
99
|
157
|
256.09360(11)#
|
7.6 h
|
β
?
|
256
Fm
|
7+#
|
β
?
, SF (.002%)
|
(various)
|
256m
Es
|
0(100)# keV
|
25.4(12) min
|
β
?
|
256
Fm
|
0+#
|
257
Es
|
99
|
158
|
257.09598(44)#
|
7.7(2) d
|
β
?
|
257
Fm
|
7/2+#
|
α?
|
253
Bk
|
This table header & footer:
|
- ^
m
Es – Excited
nuclear isomer
.
- ^
( ) – Uncertainty (1
σ
) is given in concise form in parentheses after the corresponding last digits.
- ^
# – Atomic mass marked #: value and uncertainty derived not from purely experimental data, but at least partly from trends from the Mass Surface (TMS).
- ^
Modes of decay:
- ^
( ) spin value – Indicates spin with weak assignment arguments.
- ^
a
b
# – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).
- ^
Most common isotope
- ^
Theoretically capable of electron capture to
254
Cf
[1]
References
[
edit
]
- ^
a
b
c
d
e
Kondev, F. G.; Wang, M.; Huang, W. J.; Naimi, S.; Audi, G. (2021).
"The NUBASE2020 evaluation of nuclear properties"
(PDF)
.
Chinese Physics C
.
45
(3): 030001.
doi
:
10.1088/1674-1137/abddae
.
- ^
Wang, Meng; Huang, W.J.; Kondev, F.G.; Audi, G.; Naimi, S. (2021). "The AME 2020 atomic mass evaluation (II). Tables, graphs and references*".
Chinese Physics C
.
45
(3): 030003.
doi
:
10.1088/1674-1137/abddaf
.
- ^
Khuyagbaatar, J.; Albers, H. M.; Block, M.; Brand, H.; Cantemir, R. A.; Di Nitto, A.; Dullmann, Ch. E.; Gotz, M.; Gotz, S.; Heßberger, F. P.; Jager, E.; Kindler, B.; Kratz, J. V.; Krier, J.; Kurz, N.; Lommel, B.; Lens, L.; Mistry, A.; Schausten, B.; Uusitalo, J.; Yakushev, A. (1 October 2020).
"Search for Electron-Capture Delayed Fission in the New Isotope
244
Md"
.
Physical Review Letters
.
125
(14): 142504.
Bibcode
:
2020PhRvL.125n2504K
.
doi
:
10.1103/PhysRevLett.125.142504
.
PMID
33064498
.
S2CID
223546973
.
- ^
Khuyagbaatar, J.; Cantemir, R. A.; Dullmann, Ch. E.; Jager, E.; Kindler, B.; Krier, J.; Kurz, N.; Lommel, B.; Schausten, B.; Yakushev, A. (2024-03-18). "Decay properties of the neutron-deficient isotope Es 242".
Physical Review C
.
109
(3).
doi
:
10.1103/PhysRevC.109.034311
.
ISSN
2469-9985
.
- Isotope masses from:
- Half-life, spin, and isomer data selected from the following sources.
- Audi, Georges; Bersillon, Olivier; Blachot, Jean;
Wapstra, Aaldert Hendrik
(2003),
"The N
UBASE
evaluation of nuclear and decay properties"
,
Nuclear Physics A
,
729
: 3?128,
Bibcode
:
2003NuPhA.729....3A
,
doi
:
10.1016/j.nuclphysa.2003.11.001
- National Nuclear Data Center
.
"NuDat 2.x database"
.
Brookhaven National Laboratory
.
- Holden, Norman E. (2004). "11. Table of the Isotopes". In Lide, David R. (ed.).
CRC Handbook of Chemistry and Physics
(85th ed.).
Boca Raton, Florida
:
CRC Press
.
ISBN
978-0-8493-0485-9
.
|
---|
Group
|
1
|
2
|
|
3
|
4
|
5
|
6
|
7
|
8
|
9
|
10
|
11
|
12
|
13
|
14
|
15
|
16
|
17
|
18
|
Period
|
Hydrogen and
alkali metals
|
Alkaline
earth metals
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Pnictogens
|
Chalcogens
|
Halogens
|
Noble gases
|
①
|
1
|
|
2
|
②
|
3
|
4
|
|
5
|
6
|
7
|
8
|
9
|
10
|
③
|
11
|
12
|
|
13
|
14
|
15
|
16
|
17
|
18
|
④
|
19
|
20
|
|
21
|
22
|
23
|
24
|
25
|
26
|
27
|
28
|
29
|
30
|
31
|
32
|
33
|
34
|
35
|
36
|
⑤
|
37
|
38
|
|
39
|
40
|
41
|
42
|
43
|
44
|
45
|
46
|
47
|
48
|
49
|
50
|
51
|
52
|
53
|
54
|
⑥
|
55
|
56
|
|
71
|
72
|
73
|
74
|
75
|
76
|
77
|
78
|
79
|
80
|
81
|
82
|
83
|
84
|
85
|
86
|
⑦
|
87
|
88
|
|
103
|
104
|
105
|
106
|
107
|
108
|
109
|
110
|
111
|
112
|
113
|
114
|
115
|
116
|
117
|
118
|
⑧
|
119
|
120
|
|
|
|
|
|
57
|
58
|
59
|
60
|
61
|
62
|
63
|
64
|
65
|
66
|
67
|
68
|
69
|
70
|
|
|
|
89
|
90
|
91
|
92
|
93
|
94
|
95
|
96
|
97
|
98
|
99
|
100
|
101
|
102
|
|
|