鋂是人造元素，沒有穩定同位素，也無法確認標準原子質量。目前已發現 229Am 至 247Am（231Am 除外）共 18 種同位素，以及未確認的 223Am。其中，243Am 最穩定，半衰期 7350 年。 圖表 223Am styletextalignright 95 styletextalignright 128 22304584 32 10 9 ms 219Np 92 229Am styletextalignright 95 styletextalignright 134 22904528 11 18 15 s 225Np 52 rowspan2 230Am rowspan2 styletextalignright 95 rowspan2 styletextalignright 135 rowspan2 23004603 15 rowspan2 40 9 s 70 230Pu rowspan2 1 30 various rowspan3232Am rowspan3 styletextalignright 95 rowspan3 styletextalignright 137 rowspan323204659 32 rowspan379 2 s 98 232Pu rowspan3 2 228Np 069 various rowspan2233Am rowspan2 styletextalignright 95 rowspan2 styletextalignright 138 rowspan223304635 11 rowspan232 8 min 233Pu rowspan2 229Np rowspan3234Am rowspan3 styletextalignright 95 rowspan3 styletextalignright 139 rowspan323404781 22 rowspan3232 8 min 9995 234Pu rowspan3 04 230Np SF 0066 various rowspan2235Am rowspan2 styletextalignright 95 rowspan2 styletextalignright 140 rowspan223504795 13 rowspan299 5 min 235Pu rowspan252 （不常見） 231Np rowspan2236Am rowspan2 styletextalignright 95 rowspan2 styletextalignright 141 rowspan223604958 11 rowspan236 1 min 236Pu rowspan2 232Np rowspan2237Am rowspan2 styletextalignright 95 rowspan2 styletextalignright 142 rowspan223705000 6 rowspan2730 10 min 9997 237Pu rowspan252 025 233Np rowspan2238Am rowspan2 styletextalignright 95 rowspan2 styletextalignright 143 rowspan223805198 5 rowspan298 2 min 238Pu rowspan21 104 234Np styletextindent1em 238mAm colspan3 styletextindent2em 2500 200 keV 35 10 µs rowspan2239Am rowspan2 styletextalignright 95 rowspan2 styletextalignright 144 rowspan22390530245 26 rowspan2119 1 h 9999 239Pu rowspan252 01 235Np styletextindent1em 239mAm colspan3 styletextindent2em 2500 200 keV 163 12 ns 72 rowspan2240Am rowspan2 styletextalignright 95 rowspan2 styletextalignright 145 rowspan2240055300 15 rowspan2508 3 h 240Pu rowspan23 19104 236Np rowspan3241AmMost common isotopes rowspan3 styletextalignright 95 rowspan3 styletextalignright 146 rowspan32410568291 20 rowspan34322 7 y 237Np rowspan352 741010 207Tl 34Si SF 431010 various styletextindent1em 241mAm colspan3 styletextindent2em 2200 100 keV 12 3 µs rowspan2242Am rowspan2 styletextalignright 95 rowspan2 styletextalignright 147 rowspan22420595492 20 rowspan21602 2 h 827 242Cm rowspan21 173 242Pu rowspan3 styletextindent1em 242m1Am rowspan3 colspan3 styletextindent2em 4860 5 keV rowspan3141 2 y IT 9954 242Am rowspan35 46 238Np SF 15108 various styletextindent1em 242m2Am colspan3 styletextindent2em 2200 80 keV 140 10 ms 23 rowspan2243Am rowspan2 styletextalignright 95 rowspan2 styletextalignright 148 rowspan22430613811 25 rowspan27370 40 y 239Np rowspan252 SF 37109 various 244Am styletextalignright 95 styletextalignright 149 2440642848 22 101 1 h 244Cm 6 rowspan2 styletextindent1em 244mAm rowspan2 colspan3 styletextindent2em 861 10 keV rowspan226 1 min 9996 244Cm rowspan21 0361 244Pu 245Am styletextalignright 95 styletextalignright 150 245066452 4 205 1 h 245Cm 52 246Am styletextalignright 95 styletextalignright 151 246069775 20 39 3 min 246Cm 7 rowspan2 styletextindent1em 246m1Am rowspan2 colspan3 styletextindent2em 30 10 keV rowspan2250 2 min 9999 246Cm rowspan22 IT 01 246Am styletextindent1em 246m2Am colspan3 styletextindent2em 2000 keV 73 10 µs 247Am styletextalignright 95 styletextalignright 152 24707209 11 230 13 min 247Cm 52 參考文獻 Isotope masses from Ame2003 Atomic Mass Evaluation by G Audi AH Wapstra C Thibault J Blachot and O Bersillon in Nuclear Physics A729 2003 Halflife spin and isomer data selected from these sources Editing notes on this articles talk page Audi Bersillon Blachot Wapstra The Nubase2003 evaluation of nuclear and decay properties Nuc Phys A 729 pp 3128 2003 National Nuclear Data Center Brookhaven National Laboratory Information extracted from the NuDat 21 database retrieved Sept 2005 David R Lide ed Norman E Holden in CRC Handbook of Chemistry and Physics 85th Edition online version CRC Press Boca Raton Florida 2005 Section 11 Table of the Isotopes Am Category 鋂