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 4 nuclear isomers. The longest-lived isotope is 252Es with a half-life of 471.7 days, or around 1.293 years.

List of isotopes

 * rowspan=3|240Es
 * rowspan=3 style="text-align:right" | 99
 * rowspan=3 style="text-align:right" | 141
 * rowspan=3|240.06895(39)#
 * rowspan=3|6.0(17) s
 * α (70%)
 * 236Bk
 * rowspan=3|4−#
 * β+ (30%)
 * 240Cf
 * β+, SF (0.16%)
 * (various)
 * rowspan=2|241Es
 * rowspan=2 style="text-align:right" | 99
 * rowspan=2 style="text-align:right" | 142
 * rowspan=2|241.06859(25)#
 * rowspan=2|$4.3 s$
 * α
 * 237Bk
 * rowspan=2|3/2−#
 * β+?
 * 241Cf
 * rowspan=3|242Es
 * rowspan=3 style="text-align:right" | 99
 * rowspan=3 style="text-align:right" | 143
 * rowspan=3|242.06957(28)#
 * rowspan=3|16.9(8) s
 * β+
 * 242Cf
 * rowspan=3|2+#
 * α (41%)
 * 238Bk
 * β+, SF (1.5%)
 * (various)
 * rowspan=2|243Es
 * rowspan=2 style="text-align:right" | 99
 * rowspan=2 style="text-align:right" | 144
 * rowspan=2|243.06951(22)#
 * rowspan=2|22.1(14) s
 * α (61%)
 * 239Bk
 * rowspan=2|(7/2+)
 * β+ (39%)
 * 243Cf
 * rowspan=3|244Es
 * rowspan=3 style="text-align:right" | 99
 * rowspan=3 style="text-align:right" | 145
 * rowspan=3|244.07088(20)#
 * rowspan=3|37(4) s
 * β+ (95%)
 * 244Cf
 * rowspan=3|6+#
 * α (5%)
 * 240Bk
 * β+, SF (0.011%)
 * (various)
 * rowspan=2|245Es
 * rowspan=2 style="text-align:right" | 99
 * rowspan=2 style="text-align:right" | 146
 * rowspan=2|245.07119(18)#
 * rowspan=2|1.11(6) min
 * β+ (51%)
 * 245Cf
 * rowspan=2|(3/2−)
 * α (49%)
 * 241Bk
 * rowspan=3 style="text-indent:1em" | 245mEs
 * rowspan=3 colspan="3" style="text-indent:2em" | 30(15)# keV
 * rowspan=3|>50# us
 * IT?
 * 245Es
 * rowspan=3|7/2+#
 * α?
 * 241Bk
 * β+?
 * 245Cf
 * rowspan=3|246Es
 * rowspan=3 style="text-align:right" | 99
 * rowspan=3 style="text-align:right" | 147
 * rowspan=3|246.072806(97)
 * rowspan=3|7.5(5) min
 * β+ (90.1%)
 * 246Cf
 * rowspan=3|4−#
 * α (9.9%)
 * 242Bk
 * β+, SF (.003%)
 * (various)
 * rowspan=3|247Es
 * rowspan=3 style="text-align:right" | 99
 * rowspan=3 style="text-align:right" | 148
 * rowspan=3|247.073622(21)
 * rowspan=3|4.55(26) min
 * β+ (93%)
 * 247Cf
 * rowspan=3|(7/2+)
 * α (7%)
 * 243Bk
 * SF?
 * (various)
 * rowspan=3|248Es
 * rowspan=3 style="text-align:right" | 99
 * rowspan=3 style="text-align:right" | 149
 * rowspan=3|248.075469(56)#
 * rowspan=3|24(3) min
 * β+ (99.75%)
 * 248Cf
 * rowspan=3|2−#
 * α (.25%)
 * 244Bk
 * β+, SF (3.5×10−4%)
 * (various)
 * rowspan=2|249Es
 * rowspan=2 style="text-align:right" | 99
 * rowspan=2 style="text-align:right" | 150
 * rowspan=2|249.076409(32)#
 * rowspan=2|102.2(6) min
 * β+ (99.43%)
 * 249Cf
 * rowspan=2|7/2+
 * α (.57%)
 * 245Bk
 * rowspan=2|250Es
 * rowspan=2 style="text-align:right" | 99
 * rowspan=2 style="text-align:right" | 151
 * rowspan=2|250.07861(11)#
 * rowspan=2|8.6(1) h
 * β+
 * 250Cf
 * rowspan=2|6(+)
 * α?
 * 246Bk
 * rowspan=2 style="text-indent:1em" | 250mEs
 * rowspan=2 colspan="3" style="text-indent:2em" | 200(150)# keV
 * rowspan=2|2.22(5) h
 * β+
 * 250Cf
 * rowspan=2|1(−)
 * α?
 * 246Bk
 * rowspan=2|251Es
 * rowspan=2 style="text-align:right" | 99
 * rowspan=2 style="text-align:right" | 152
 * rowspan=2|251.0799914(57)
 * rowspan=2|33(1) h
 * EC (99.5%)
 * 251Cf
 * rowspan=2|3/2−
 * α (.5%)
 * 247Bk
 * rowspan=2|252Es
 * rowspan=2 style="text-align:right" | 99
 * rowspan=2 style="text-align:right" | 153
 * rowspan=2|252.082979(54)
 * rowspan=2|471.7(19) d
 * α (78(2)%)
 * 248Bk
 * rowspan=2|(4+)
 * EC (22(2)%)
 * 252Cf
 * rowspan=2|253Es
 * rowspan=2 style="text-align:right" | 99
 * rowspan=2 style="text-align:right" | 154
 * rowspan=2|253.0848212(13)
 * rowspan=2|20.47(3) d
 * α
 * 249Bk
 * rowspan=2|7/2+
 * SF (8.7×10−6%)
 * (various)
 * rowspan=3|254Es
 * rowspan=3 style="text-align:right" | 99
 * rowspan=3 style="text-align:right" | 155
 * rowspan=3|254.0880243(32)
 * rowspan=3|275.7(5) d
 * α
 * 250Bk
 * rowspan=3|7+
 * β− (1.74×10−4%)
 * 254Fm
 * SF (<3×10−6%)
 * (various)
 * rowspan=5 style="text-indent:1em" | 254mEs
 * rowspan=5 colspan="3" style="text-indent:2em" | 80.4(11) keV
 * rowspan=5|39.3(2) h
 * β− (98(2)%)
 * 254Fm
 * rowspan=5|2+
 * IT (<3%)
 * 254Es
 * α (0.32(1)%)
 * 250Bk
 * EC (0.076(7)%)
 * 254Cf
 * SF (<0.045%)
 * (various)
 * rowspan=3|255Es
 * rowspan=3 style="text-align:right" | 99
 * rowspan=3 style="text-align:right" | 156
 * rowspan=3|255.090274(12)
 * rowspan=3|39.8(12) d
 * β− (92.0%)
 * 255Fm
 * rowspan=3|(7/2+)
 * α (8.0%)
 * 251Bk
 * SF (.0041%)
 * (various)
 * rowspan=2|256Es
 * rowspan=2| 99
 * rowspan=2| 157
 * rowspan=2| 256.09360(11)#
 * rowspan=2|7.6 h
 * β−
 * 256Fm
 * rowspan=2|7+#
 * β−, SF (.002%)
 * (various)
 * style="text-indent:1em" |256mEs
 * colspan="3" style="text-indent:2em" | 0(100)# keV
 * 25.4(12) min
 * β−
 * 256Fm
 * 0+#
 * rowspan=2|257Es
 * rowspan=2 style="text-align:right" | 99
 * rowspan=2 style="text-align:right" | 158
 * rowspan=2|257.09598(44)#
 * rowspan=2|7.7(2) d
 * β−
 * 257Fm
 * rowspan=2|7/2+#
 * α?
 * 253Bk
 * α (0.32(1)%)
 * 250Bk
 * EC (0.076(7)%)
 * 254Cf
 * SF (<0.045%)
 * (various)
 * rowspan=3|255Es
 * rowspan=3 style="text-align:right" | 99
 * rowspan=3 style="text-align:right" | 156
 * rowspan=3|255.090274(12)
 * rowspan=3|39.8(12) d
 * β− (92.0%)
 * 255Fm
 * rowspan=3|(7/2+)
 * α (8.0%)
 * 251Bk
 * SF (.0041%)
 * (various)
 * rowspan=2|256Es
 * rowspan=2| 99
 * rowspan=2| 157
 * rowspan=2| 256.09360(11)#
 * rowspan=2|7.6 h
 * β−
 * 256Fm
 * rowspan=2|7+#
 * β−, SF (.002%)
 * (various)
 * style="text-indent:1em" |256mEs
 * colspan="3" style="text-indent:2em" | 0(100)# keV
 * 25.4(12) min
 * β−
 * 256Fm
 * 0+#
 * rowspan=2|257Es
 * rowspan=2 style="text-align:right" | 99
 * rowspan=2 style="text-align:right" | 158
 * rowspan=2|257.09598(44)#
 * rowspan=2|7.7(2) d
 * β−
 * 257Fm
 * rowspan=2|7/2+#
 * α?
 * 253Bk
 * rowspan=2|257Es
 * rowspan=2 style="text-align:right" | 99
 * rowspan=2 style="text-align:right" | 158
 * rowspan=2|257.09598(44)#
 * rowspan=2|7.7(2) d
 * β−
 * 257Fm
 * rowspan=2|7/2+#
 * α?
 * 253Bk
 * 253Bk