Isotopes of einsteinium

Einsteinium (₉₉Es) 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 ²⁵³Es in 1952. There are 18 known radioisotopes, from ²⁴⁰Es to ²⁵⁷Es, and 8 nuclear isomers. The longest-lived isotope is ²⁵²Es with a half-life of 471.7 days or 1.291 years; the second longest, ²⁵⁴Es with half-life of 275.7 days is more available.

List of isotopes

|-id=Einsteinium-240 | rowspan=3|²⁴⁰Es | rowspan=3 style="text-align:right" | 99 | rowspan=3 style="text-align:right" | 141 | rowspan=3|240.06895(39)# | rowspan=3| | α (70%) | ²³⁶Bk | rowspan=3|4−# |- | β⁺ (30%) | ²⁴⁰Cf |- | β⁺, SF (0.16%) | (various) |-id=Einsteinium-241 | ²⁴¹Es | style="text-align:right" | 99 | style="text-align:right" | 142 | 241.06859(25)# | | α | ²³⁷Bk | 3/2−# |-id=Einsteinium-242 | rowspan=3|²⁴²Es | rowspan=3 style="text-align:right" | 99 | rowspan=3 style="text-align:right" | 143 | rowspan=3|242.06957(28)# | rowspan=3| | β⁺ | ²⁴²Cf | rowspan=3|2+# |- | α (41%) | ²³⁸Bk |- | β⁺, SF (1.5%) | (various) |-id=Einsteinium-243 | rowspan=2|²⁴³Es | rowspan=2 style="text-align:right" | 99 | rowspan=2 style="text-align:right" | 144 | rowspan=2|243.06951(22)# | rowspan=2| | α (61%) | ²³⁹Bk | rowspan=2|(7/2+) |- | β⁺? (39%) | ²⁴³Cf |-id=Einsteinium-243m | rowspan=3 style="text-indent:1em" | ^243mEs | rowspan=3 colspan=3 style="text-indent:2em" | 50(50)#&nbsp;keV | rowspan=3|>50#&nbsp;μs | IT? | ²⁴³Es | rowspan=3|3/2−# |- | α? | ²³⁹Bk |- | β⁺? | ²⁴³Cf |-id=Einsteinium-244 | rowspan=3|²⁴⁴Es | rowspan=3 style="text-align:right" | 99 | rowspan=3 style="text-align:right" | 145 | rowspan=3|244.07088(20)# | rowspan=3| | β⁺ (95%) | ²⁴⁴Cf | rowspan=3|6+# |- | α (5%) | ²⁴⁰Bk |- | β⁺, SF (0.011%) | (various) |-id=Einsteinium-245 | rowspan=2|²⁴⁵Es | rowspan=2 style="text-align:right" | 99 | rowspan=2 style="text-align:right" | 146 | rowspan=2|245.07119(18)# | rowspan=2| | β⁺ (51%) | ²⁴⁵Cf | rowspan=2|(3/2−) |- | α (49%) | ²⁴¹Bk |-id=Einsteinium-245m | rowspan=3 style="text-indent:1em" | ^245mEs | rowspan=3 colspan="3" style="text-indent:2em" | 30(15)#&nbsp;keV | rowspan=3|>50#&nbsp;μs | IT? | ²⁴⁵Es | rowspan=3|7/2+# |- | α? | ²⁴¹Bk |- | β⁺? | ²⁴⁵Cf |-id=Einsteinium-246 | rowspan=3|²⁴⁶Es | rowspan=3 style="text-align:right" | 99 | rowspan=3 style="text-align:right" | 147 | rowspan=3|246.07281(10) | rowspan=3| | β⁺ (90.1%) | ²⁴⁶Cf | rowspan=3|4−# |- | α (9.9%) | ²⁴²Bk |- | β⁺, SF (0.003%) | (various) |-id=Einsteinium-247 | rowspan=2|²⁴⁷Es | rowspan=2 style="text-align:right" | 99 | rowspan=2 style="text-align:right" | 148 | rowspan=2|247.073622(21) | rowspan=2| | β⁺ (93%) | ²⁴⁷Cf | rowspan=2|(7/2+) |- | α (7%) | ²⁴³Bk |-id=Einsteinium-247m | rowspan=3 style="text-indent:1em" | ^247mEs | rowspan=3 colspan=3 style="text-indent:2em" | 50(50)#&nbsp;keV | rowspan=3|>20#&nbsp;μs | IT? | ²⁴⁷Es | rowspan=3|(3/2−) |- | α? | ²⁴³Bk |- | β⁺ | ²⁴⁷Cf |-id=Einsteinium-248 | rowspan=3|²⁴⁸Es | rowspan=3 style="text-align:right" | 99 | rowspan=3 style="text-align:right" | 149 | rowspan=3|248.07547(6)# | rowspan=3| | β⁺ (99.75%) | ²⁴⁸Cf | rowspan=3|2−# |- | α (0.25%) | ²⁴⁴Bk |- | β⁺, SF (3.5×10^{−4}%) | (various) |-id=Einsteinium-249 | rowspan=2|²⁴⁹Es | rowspan=2 style="text-align:right" | 99 | rowspan=2 style="text-align:right" | 150 | rowspan=2|249.07641(3)# | rowspan=2| | β⁺ (99.43%) | ²⁴⁹Cf | rowspan=2|7/2+ |- | α (0.57%) | ²⁴⁵Bk |-id=Einsteinium-250 | ²⁵⁰Es | style="text-align:right" | 99 | style="text-align:right" | 151 | 250.07861(11)# | | β⁺ | ²⁵⁰Cf | 6(+) |-id=Einsteinium-250m | style="text-indent:1em" | ^250mEs | colspan="3" style="text-indent:2em" | 200(150)#&nbsp;keV | | β⁺ | ²⁵⁰Cf | 1(−) |-id=Einsteinium-251 | rowspan=2|²⁵¹Es | rowspan=2 style="text-align:right" | 99 | rowspan=2 style="text-align:right" | 152 | rowspan=2|251.079991(6) | rowspan=2| | EC (99.5%) | ²⁵¹Cf | rowspan=2|3/2− |- | α (0.5%) | ²⁴⁷Bk |-id=Einsteinium-251m | rowspan=2 style="text-indent:1em" | ^251mEs | rowspan=2 colspan=3 style="text-indent:2em" | 8.4(10)&nbsp;keV | rowspan=2 | >200#&nbsp;μs | IT? | ²⁵¹Es | rowspan=2|(7/2+) |- | EC? | ²⁵¹Cf |-id=Einsteinium-252 | rowspan=2|²⁵²Es | rowspan=2 style="text-align:right" | 99 | rowspan=2 style="text-align:right" | 153 | rowspan=2|252.08298(5) | rowspan=2| | α (78%) | ²⁴⁸Bk | rowspan=2|(4+) |- | EC (22%) | ²⁵²Cf |-id=Einsteinium-253 | rowspan=2|²⁵³Es | rowspan=2 style="text-align:right" | 99 | rowspan=2 style="text-align:right" | 154 | rowspan=2|253.0848212(13) | rowspan=2| | α | ²⁴⁹Bk | rowspan=2|7/2+ |- | SF (8.7×10^{−6}%) | (various) |-id=Einsteinium-253m | style="text-indent:1em" | ^253mEs | colspan=3 style="text-indent:2em" | 106(4)&nbsp;keV | >10#&nbsp;μs | IT? | ²⁵³Es | 3/2−# |-id=Einsteinium-254 | rowspan=3|²⁵⁴Es | rowspan=3 style="text-align:right" | 99 | rowspan=3 style="text-align:right" | 155 | rowspan=3|254.088024(3) | rowspan=3| | α | ²⁵⁰Bk | rowspan=3|7+ |- | β^− (1.74×10^{−4}%) | ²⁵⁴Fm |- | SF (<3×10^{−6}%) | (various) |-id=Einsteinium-254m | rowspan=5 style="text-indent:1em" | ^254mEs | rowspan=5 colspan="3" style="text-indent:2em" | 80.4(11)&nbsp;keV | rowspan=5| | β^− (98%) | ²⁵⁴Fm | rowspan=5|2+ |- | IT (<3%) | ²⁵⁴Es |- | α (0.32%) | ²⁵⁰Bk |- | EC (0.076%) | ²⁵⁴Cf |- | SF (<0.045%) | (various) |-id=Einsteinium-255 | rowspan=3|²⁵⁵Es | rowspan=3 style="text-align:right" | 99 | rowspan=3 style="text-align:right" | 156 | rowspan=3|255.090274(12) | rowspan=3| | β^− (92.0%) | ²⁵⁵Fm | rowspan=3|(7/2+) |- | α (8.0%) | ²⁵¹Bk |- | SF (0.0041%) | (various) |-id=Einsteinium-256 | rowspan=2|²⁵⁶Es | rowspan=2 style="text-align:right" | 99 | rowspan=2 style="text-align:right" | 157 | rowspan=2| 256.09360(11)# | rowspan=2| | β^− | ²⁵⁶Fm | rowspan=2|7+# |- | β^−, SF (0.002%) | (various) |-id=Einsteinium-256m | style="text-indent:1em" |^256mEs | colspan="3" style="text-indent:2em" | 0(100)#&nbsp;keV | | β^− | ²⁵⁶Fm | 0+# |-id=Einsteinium-257 | ²⁵⁷Es | style="text-align:right" | 99 | style="text-align:right" | 158 | 257.09598(44)# | | β^− | ²⁵⁷Fm | 7/2+#

References