Neptünyum İzotopları​

Neptünyum (Np) kararlı izotoplara sahip değildir. Standart bir atom ağırlığı yoktur. 225Np 93 132 225.03391(8) 3# ms 9/2-# 226Np 93 133 226.03515(10)# 35(10) ms 227Np 93 134 227.03496(8) 510(60) ms 5/2-# 228Np 93 135 228.03618(21)# 61.4(14) s 229Np 93 136 229.03626(9) 4.0(2) min 5/2+# 230Np 93 137 230.03783(6) 4.6(3) min 231Np 93 138 231.03825(5) 48.8(2) min (5/2)(+#) 232Np 93 139 232.04011(11)# 14.7(3) min (4+) 233Np 93 140 233.04074(5) 36.2(1) min (5/2+) 234Np 93 141 234.042895(9) 4.4(1) d (0+) 235Np 93 142 235.0440633(21) 396.1(12) d 5/2+ 236Np 93 143 236.04657(5) 154(6)E+3 a (6-) 236mNp 60(50) keV 22.5(4) h 1 237Np 93 144 237.0481734(20) 2.144(7)E+6 a 5/2+ 238Np 93 145 238.0509464(20) 2.117(2) d 2+ 238mNp 2300(200)# keV 112(39) ns 239Np 93 146 239.0529390(22) 2.356(3) d 5/2+ 240Np 93 147 240.056162(16) 61.9(2) min (5+) 240mNp 20(15) keV 7.22(2) min 1(+) 241Np 93 148 241.05825(8) 13.9(2) min (5/2+) 242Np 93 149 242.06164(21) 2.2(2) min (1+) 242mNp 0(50)# keV 5.5(1) min 6+# 243Np 93 150 243.06428(3)# 1.85(15) min (5/2-) 244Np 93 151 244.06785(32)# 2.29(16) min (7-)