Isotopes of mendelevium

Mendelevium (101Md) is a synthetic element, and thus a standard atomic weight cannot be given. Like all artificial elements, it has no stable isotopes. The first isotope to be synthesized was 256Md (which was also the first isotope of any element produced one atom at a time) in 1955. There are 17 known radioisotopes, ranging in atomic mass from 244Md to 260Md, and 5 isomers. The longest-lived isotope is 258Md with a half-life of 51.3 days, and the longest-lived isomer is 258mMd with a half-life of 57 minutes.

List of isotopes

 * 244Md
 * style="text-align:right" | 101
 * style="text-align:right" | 143
 * α
 * 240Es
 * α
 * 240Es
 * 240Es


 * rowspan=2|245Md
 * rowspan=2 style="text-align:right" | 101
 * rowspan=2 style="text-align:right" | 144
 * rowspan=2|245.08081(33)#
 * rowspan=2|$0.3 s$
 * α
 * 241Es
 * rowspan=2|7/2−#
 * β+ (rare)
 * 245Fm
 * style="text-indent:1em" | 245mMd
 * colspan="3" style="text-indent:2em" | 200(100)# keV
 * 0.90(25) ms
 * SF
 * (various)
 * 1/2−#
 * rowspan=2|246Md
 * rowspan=2 style="text-align:right" | 101
 * rowspan=2 style="text-align:right" | 145
 * rowspan=2|246.08171(28)#
 * rowspan=2|0.9(2) s
 * α
 * 242Es
 * rowspan=2|
 * β+?
 * 246Fm
 * rowspan=3 style="text-indent:1em" | 246mMd
 * rowspan=3 colspan="3" style="text-indent:2em" | 60(60) keV
 * rowspan=3|4.4(8) s
 * β+ (>67%)
 * 246Fm
 * rowspan=3|
 * α (<23%)
 * 242Es
 * β+, SF (>10%)
 * (various)
 * rowspan=3|247Md
 * rowspan=3 style="text-align:right" | 101
 * rowspan=3 style="text-align:right" | 146
 * rowspan=3|247.08152(22)#
 * rowspan=3|1.20(12) s
 * α (99.14%)
 * 243Es
 * rowspan=3|(7/2−)
 * SF (0.86%)
 * (various)
 * β+?
 * 247Fm
 * rowspan=2 style="text-indent:1em" | 247mMd
 * rowspan=2 colspan="3" style="text-indent:2em" | 153 keV
 * rowspan=2|0.23(3) s
 * α (80%)
 * 243Es
 * rowspan=2|(1/2−)
 * SF (20%)
 * (various)
 * rowspan=3|248Md
 * rowspan=3 style="text-align:right" | 101
 * rowspan=3 style="text-align:right" | 147
 * rowspan=3|248.08282(26)#
 * rowspan=3|7(3) s
 * β+ (80%)
 * 248Fm
 * rowspan=3|
 * α (20%)
 * 244Es
 * β+, SF (.05%)
 * (various)
 * rowspan=2|249Md
 * rowspan=2 style="text-align:right" | 101
 * rowspan=2 style="text-align:right" | 148
 * rowspan=2|249.08291(22)#
 * rowspan=2|26(1) s
 * α (75%)
 * 245Es
 * rowspan=2|(7/2−)
 * β+ (25%)
 * 249Fm
 * style="text-indent:1em" | 249mMd
 * colspan="3" style="text-indent:2em" | 100(100)# keV
 * α
 * 245Es
 * (1/2−)
 * rowspan=3|250Md
 * rowspan=3 style="text-align:right" | 101
 * rowspan=3 style="text-align:right" | 149
 * rowspan=3|250.08442(32)#
 * rowspan=3|54(4) s
 * β+ (93.0%)
 * 250Fm
 * rowspan=3|
 * α (7.0%)
 * 246Es
 * β+, SF (0.026%)
 * (various)
 * rowspan=2|251Md
 * rowspan=2 style="text-align:right" | 101
 * rowspan=2 style="text-align:right" | 150
 * rowspan=2|251.084774(20)
 * rowspan=2|4.27(26) min
 * β+ (90%)
 * 251Fm
 * rowspan=2|(7/2−)
 * α (10%)
 * 247Es
 * rowspan=2|252Md
 * rowspan=2 style="text-align:right" | 101
 * rowspan=2 style="text-align:right" | 151
 * rowspan=2|252.08643(14)#
 * rowspan=2|2.3(8) min
 * β+
 * 252Fm
 * rowspan=2|
 * α (rare)
 * 248Es
 * rowspan=2|253Md
 * rowspan=2 style="text-align:right" | 101
 * rowspan=2 style="text-align:right" | 152
 * rowspan=2|253.08714(3)#
 * rowspan=2|12(8) min [$0.33 s$]
 * β+ (~99%)
 * 253Fm
 * rowspan=2|(7/2−)
 * α (~1%)
 * 249Es
 * rowspan=2|254Md
 * rowspan=2 style="text-align:right" | 101
 * rowspan=2 style="text-align:right" | 153
 * rowspan=2|254.08959(11)#
 * rowspan=2|10(3) min
 * β+
 * 254Fm
 * rowspan=2|(0−)
 * α (rare)
 * 250Es
 * rowspan=2 style="text-indent:1em" | 254mMd
 * rowspan=2 colspan="3" style="text-indent:2em" | 50(100)# keV
 * rowspan=2|28(8) min
 * β+
 * 254Fm
 * rowspan=2|(3−)
 * α (rare)
 * 250Es
 * rowspan=3|255Md
 * rowspan=3 style="text-align:right" | 101
 * rowspan=3 style="text-align:right" | 154
 * rowspan=3|255.091084(7)
 * rowspan=3|27(2) min
 * β+ (92%)
 * 255Fm
 * rowspan=3|(7/2−)
 * α (8%)
 * 251Es
 * SF (.15%)
 * (various)
 * rowspan=2|256Md
 * rowspan=2 style="text-align:right" | 101
 * rowspan=2 style="text-align:right" | 155
 * rowspan=2|256.09389(13)#
 * rowspan=2|77(2) min
 * β+ (89%)
 * 256Fm
 * rowspan=2|(1−)
 * α (11%)
 * 252Es
 * rowspan=3|257Md
 * rowspan=3 style="text-align:right" | 101
 * rowspan=3 style="text-align:right" | 156
 * rowspan=3|257.0955424(29)
 * rowspan=3|5.52(5) h
 * EC (84.8%)
 * 257Fm
 * rowspan=3|(7/2−)
 * α (15.2%)
 * 253Es
 * SF (rare)
 * (various)
 * rowspan=3|258Md
 * rowspan=3 style="text-align:right" | 101
 * rowspan=3 style="text-align:right" | 157
 * rowspan=3|258.098431(5)
 * rowspan=3|51.59(29) d
 * α
 * 254Es
 * rowspan=3|(8−)#
 * β− (<0.0015%)
 * 258No
 * β+ (<0.0015%)
 * 258Fm
 * rowspan=4 style="text-indent:1em" | 258mMd
 * rowspan=4 colspan="3" style="text-indent:2em" | 0(200)# keV
 * rowspan=4|57.0(9) min
 * EC
 * 258Fm
 * rowspan=4|1−#
 * SF (<15%)
 * (various)
 * α (<1.2%)
 * 254Es
 * β− (rare)
 * 258No
 * rowspan=2|259Md
 * rowspan=2 style="text-align:right" | 101
 * rowspan=2 style="text-align:right" | 158
 * rowspan=2|259.10051(22)#
 * rowspan=2|1.60(6) h
 * SF
 * (various)
 * rowspan=2|7/2−#
 * α (rare)
 * 255Es
 * rowspan=4|260Md
 * rowspan=4 style="text-align:right" | 101
 * rowspan=4 style="text-align:right" | 159
 * rowspan=4|260.10365(34)#
 * rowspan=4|27.8(8) d
 * SF
 * (various)
 * rowspan=4|
 * α (<5%)
 * 256Es
 * EC (<5%)
 * 260Fm
 * β− (<3.5%)
 * 260No
 * 254Es
 * rowspan=3|(8−)#
 * β− (<0.0015%)
 * 258No
 * β+ (<0.0015%)
 * 258Fm
 * rowspan=4 style="text-indent:1em" | 258mMd
 * rowspan=4 colspan="3" style="text-indent:2em" | 0(200)# keV
 * rowspan=4|57.0(9) min
 * EC
 * 258Fm
 * rowspan=4|1−#
 * SF (<15%)
 * (various)
 * α (<1.2%)
 * 254Es
 * β− (rare)
 * 258No
 * rowspan=2|259Md
 * rowspan=2 style="text-align:right" | 101
 * rowspan=2 style="text-align:right" | 158
 * rowspan=2|259.10051(22)#
 * rowspan=2|1.60(6) h
 * SF
 * (various)
 * rowspan=2|7/2−#
 * α (rare)
 * 255Es
 * rowspan=4|260Md
 * rowspan=4 style="text-align:right" | 101
 * rowspan=4 style="text-align:right" | 159
 * rowspan=4|260.10365(34)#
 * rowspan=4|27.8(8) d
 * SF
 * (various)
 * rowspan=4|
 * α (<5%)
 * 256Es
 * EC (<5%)
 * 260Fm
 * β− (<3.5%)
 * 260No
 * SF
 * (various)
 * rowspan=4|
 * α (<5%)
 * 256Es
 * EC (<5%)
 * 260Fm
 * β− (<3.5%)
 * 260No
 * β− (<3.5%)
 * 260No
 * 260No