Isotopes of mendelevium
List of isotopes
Abbreviations: EC: Electron capture IT: Isomeric transition SF: Spontaneous fission Not directly synthesized, occurs as decay product of ²⁵⁹No

Isotopes of mendelevium

Section Title: List of isotopes
Table Section Text: Abbreviations: EC: Electron capture IT: Isomeric transition SF: Spontaneous fission Not directly synthesized, occurs as decay product of ²⁵⁹No

nuclide symbol	Z(p)	N(n)	isotopic mass (u)	half-life	decay mode(s)	daughter isotope(s)	nuclear spin and parity

excitation energy

245Md	101	144	245.08081(33)#	0.90(25) ms	SF	(various)	(1/2−)#

α (rare)	241Es

245mMd	200(100)# keV	400(200) ms [0.35(+23−16) s]	α	241Es	(7/2+)

β+ (rare)	245Fm

246Md	101	145	246.08171(28)#	1.0(4) s	α	242Es

β+ (rare)	246Fm

247Md	101	146	247.08152(22)#	1.12(22) s	SF	(various)	1/2−#

α (rare)	243Es

247mMd	~0.2 s	α (99.99%)	243Es

SF (10−4%)	(various)

248Md	101	147	248.08282(26)#	7(3) s	β+ (80%)	248Fm

α (20%)	244Es

β+, SF (.05%)	(various)

249Md	101	148	249.08291(22)#	24(4) s	α (60%)	245Es	(7/2−)

β+ (40%)	249Fm

249mMd	100(100)# keV	1.9(9) s	(1/2−)

250Md	101	149	250.08442(32)#	52(6) s	β+ (93%)	250Fm

α (7%)	246Es

β+, SF (.02%)	(various)

251Md	101	150	251.084774(20)	4.0(5) min	β+ (90%)	251Fm	7/2−#

α (10%)	247Es

252Md	101	151	252.08643(14)#	2.3(8) min	β+ (50%)	252Fm

α (50%)	248Es

253Md	101	152	253.08714(3)#	12(8) min [6(+12−3) min]	β+	253Fm	7/2−#

α	249Es

254Md	101	153	254.08959(11)#	10(3) min	β+	254Fm	(0−)

α (rare)	250Es

254mMd	50(100)# keV	28(8) min	β+	254Fm	(3−)

α (rare)	250Es

255Md	101	154	255.091084(7)	27(2) min	β+ (92%)	255Fm	(7/2−)

α (8%)	251Es

SF (.15%)	(various)

256Md	101	155	256.09389(13)#	77(2) min	β+ (89%)	256Fm	(1−)

α (11%)	252Es

257Md	101	156	257.0955424(29)	5.52(5) h	EC (84.8%)	257Fm	(7/2−)

α (15.2%)	253Es

SF (1%)	(various)

258Md	101	157	258.098431(5)	51.5(3) d	α (99.99%)	254Es	(8−)#

β− (.0015%)	258No

β+ (.0015%)	258Fm

258mMd	0(200)# keV	57.0(9) min	EC (70%)	258Fm	1−#

SF (20%)	(various)

β− (10%)	258No

α (1.2%)	254Es

259Md	101	158	259.10051(22)#	1.60(6) h	SF (98.7%)	(various)	7/2−#

α (1.3%)	255Es

260Md	101	159	260.10365(34)#	27.8(8) d	SF (85%)	(various)

α (5%)	256Es

EC (5%)	260Fm

β− (3.5%)	260No

Sentence(s)

The longest-lived isotope is ²⁵⁸Md.

final_sentence: The longest-lived isotope is ²⁵⁸Md.