Isotopes of lawrencium

Lawrencium (Lr) is an artificial element, and thus a standard atomic mass cannot be given. Like all artificial elements, it has no stable isotopes. The first isotope to be synthesized was 258Lr in 1961. There are eleven known radioisotopes from 252Lr to 262Lr, and 1 isomer (253mLr). The longest-lived isotope is 262Lr with a half-life of 216 minutes. Heavier isotopes are expected to have longer half-lives.

Table

nuclide
symbol
Z(p) N(n)  
isotopic mass (u)
 
half-life decay
mode(s)[1][n 1]
daughter
isotope(s)
nuclear
spin
excitation energy
252Lr[n 2] 103 149 252.09537(27)# 390(90) ms
[0.36(+11-7) s]
α (90%) 248Md
β+ (10%) 252No
SF (1%) (various)
253Lr[n 3] 103 150 253.09521(24)# 580(70) ms
[0.57(+7-6) s]
α (90%) 249Md (7/2-)
SF (9%) (various)
β+ (1%) 253No
253mLr[n 3] 30(100)# keV 1.5(3) s
[1.5(+3-2) s]
(1/2-)
254Lr[n 4] 103 151 254.09645(36)# 13(3) s α (78%) 250Md
β+ (22%) 254No
SF (.1%) (various)
255Lr 103 152 255.09668(22)# 22(4) s α (69%) 251Md 7/2-#
β+ (30%) 255No
SF (1%) (various)
256Lr 103 153 256.09863(24)# 27(3) s α (80%) 252Md
β+ (20%) 256No
SF (.01%) (various)
257Lr 103 154 257.09956(22)# 646(25) ms α (99.99%) 253Md 9/2+#
β+ (.01%) 257No
SF (.001%) (various)
258Lr 103 155 258.10181(11)# 4.1(3) s α (95%) 254Md
β+ (5%) 258No
259Lr 103 156 259.10290(8)# 6.2(3) s α (77%) 255Md 9/2+#
SF (23%) (various)
β+ (.5%) 259No
260Lr 103 157 260.10550(12)# 2.7 min α (75%) 256Md
β+ (15%) 260No
SF (10%) (various)
261Lr 103 158 261.10688(22)# 44 min SF (various)
α (rare) 257Md
262Lr 103 159 262.10963(22)# 216 min β+ 262No
α (rare) 258Md
  1. ^ Abbreviations:
    SF: Spontaneous fission
  2. ^ Not directly synthesized, occurs as a decay product of 256Db
  3. ^ a b Not directly synthesized, occurs as a decay product of 257Db
  4. ^ Not directly synthesized, occurs as a decay product of 258Db

Notes

References

  1. ^ http://www.nucleonica.net/unc.aspx
Isotopes of nobelium Isotopes of lawrencium Isotopes of rutherfordium
Index to isotope pages · Table of nuclides