Fm
Фермій
Z 100 257,0 г/мольАктиноїд Радіоактивний
| 241Fm | 141 | 241,0743 | 69 220,0 | --- | 730,0 мкс | (5/2+) | α→237Cf(<14%) β⁺→241Es(<12%) SF | 2008 |
| 242Fm | 142 | 242,0734 | 68 400,0 | --- | 800,0 мкс | 0+ | SF(100%) α→238Cf | 1975 |
| 243Fm | 143 | 243,0744 | 69 320,0 | --- | 231,0 мс | (7/2-) | α→239Cf(91%) SF(9%) β⁺→243Es | 1981 |
| 244Fm | 144 | 244,074 | 68 960,0 | --- | 3,12 мс | 0+ | SF(>97%) β⁺→244Es(<2%) α→240Cf(<1%) | 1967 |
| 245Fm | 145 | 245,0754 | 70 190,0 | --- | 4,2 с | (1/2+) | α→241Cf(100%) β⁺→245Es(<7%) SF(<0,3%) | 1967 |
| 246Fm | 146 | 246,0754 | 70 191,0 | --- | 1,54 с | 0+ | α→242Cf(93,2%) SF(6,8%) EC→246Es(<1,3%) | 1966 |
| 247Fm | 147 | 247,0769 | 71 670,0 | --- | 31,0 с | (7/2+) | α→243Cf(64%) β⁺→247Es | 1967 |
| 247mFm | 147 | 247,077 | 71 720,0 | --- | 5,1 с | (1/2+) | α→243Cf(88%) β⁺→247Es γ→247Fm | 1967 |
| 248Fm | 148 | 248,0772 | 71 898,0 | --- | 34,5 с | 0+ | α→244Cf(~100%) SF(0,1%) β⁺→248Es | 1958 |
| 248mFm | 148 | 248,0785 | 73 100,0 | --- | 10,1 мс | (6+) | γ→248Fm α→244Cf β⁺→248Es | 2010 |
| 249Fm | 149 | 249,0789 | 73 519,0 | --- | 1,6 хв | 7/2+ | α→245Cf(33%) β⁺→249Es | 1960 |
| 250Fm | 150 | 250,0795 | 74 072,0 | --- | 31,0 хв | 0+ | α→246Cf(~100%) SF(0,007%) EC→250Es | 1954 |
| 250mFm | 150 | 250,0808 | 75 271,0 | --- | 1,92 с | (8-) | γ→250Fm(100%) α→246Cf β⁺→250Es SF | 1973 |
| 251Fm | 151 | 251,0815 | 75 959,0 | --- | 5,3 год | 9/2- | β⁺→251Es(98,2%) α→247Cf(1,8%) | 1957 |
| 251mFm | 151 | 251,0818 | 76 159,0 | --- | 21,8 мкс | 5/2+ | γ→251Fm(100%) | 1970 |
| 252Fm | 152 | 252,0825 | 76 817,0 | --- | 1,06 д | 0+ | α→248Cf(~100%) SF(0,002%) β⁺ | 1956 |
| 253Fm | 153 | 253,0852 | 79 345,5 | --- | 3,0 д | 1/2+ | EC→253Es(88%) α→249Cf(12%) | 1957 |
| 253mFm | 153 | 253,0853 | 79 486,0 | --- | --- | (7/2+) | γ→253Fm | --- |
| 253nFm | 153 | 253,0856 | 79 697,0 | --- | 560,0 нс | (11/2-) | γ→253Fm(100%) | 2011 |
| 254Fm | 154 | 254,0869 | 80 902,5 | --- | 3,24 год | 0+ | α→250Cf(99,941%) SF(0,059%) | 1954 |
| 255Fm | 155 | 255,09 | 83 800,0 | --- | 20,07 год | 7/2+ | α→251Cf(~100%) SF(2,4е-5%) | 1954 |
| 256Fm | 156 | 256,0918 | 85 485,0 | --- | 2,62 год | 0+ | SF(91,9%) α→252Cf(8,1%) | 1955 |
| 257Fm | 157 | 257,0951 | 88 590,0 | --- | 100,5 д | 9/2+ | α→253Cf(99,79%) SF(0,21%) | 1964 |
| 258Fm | 158 | 258,0971 | 90 430,0 | --- | 370,0 мкс | 0+ | SF(100%) α→254Cf | 1971 |
| 259Fm | 159 | 259,1006 | 93 700,0 | --- | 1,5 с | --- | SF(100%) | 1980 |
| 260Fm | 160 | 260,1028 | 95 770,0 | --- | 1,0 хв | 0+ | SF | --- |