编辑“︁钫”︁（章节）

==同位素==
{{main|鈁的同位素}}
鈁共有34個[[同位素]]，[[質量數]]從199到232不等，<ref name="CRC2006P180">{{Cite book |year = 2006 |title = CRC Handbook of Chemistry and Physics |editor-last = Lide |editor-first = David R. |volume = 11 |pages = 180–181 |publisher = CRC |isbn=0-8493-0487-3}}</ref>另有7種[[亞穩態]][[同核異構體]]<ref name="CRC2006P180" />。所有鈁同位素都具有極高的[[放射性]]，半衰期很短，非常不穩定。只有鈁-223和鈁-221存在於自然界中，其中鈁-221罕見得多。<ref name="nostrand679">{{cite book|year = 2005|title= Francium, in Van Nostrand's Encyclopedia of Chemistry|url = https://archive.org/details/vannostrandsency0036unse|editor-last = Considine| editor-first = Glenn D.| page= [https://archive.org/details/vannostrandsency0036unse/page/678 679]|location= New York| publisher = Wiley-Interscience| isbn = 0-471-61525-0}}</ref>

鈁-223是最長壽的鈁同位素，半衰期為21.8分鐘。<ref name="CRC2006P180" />再發現或合成半衰期更長的鈁同位素的可能性極低。<ref name="mcgraw" />鈁-223是[[錒衰變系]]的第五個產物，是[[錒]]-227的子同位素，錒-227-{只}-有1.38%的概率會[[α衰變]]成鈁-223。<ref name="nostrand332">{{cite book|year = 2005|title= Chemical Elements, in Van Nostrand's Encyclopedia of Chemistry|url = https://archive.org/details/vannostrandsency0036unse|editor-last = Considine| editor-first = Glenn D.|page=[https://archive.org/details/vannostrandsency0036unse/page/332 332]|location= New York| publisher = Wiley-Interscience| isbn = 0-471-61525-0}}</ref>鈁-223會再[[β衰變]]為[[鐳]]-223（衰變能量為1149&nbsp;keV），另有0.006%的α衰變路徑，產物為[[砹]]-219（衰變能量為5.4&nbsp;MeV）。<ref>{{cite web |author=National Nuclear Data Center |year=1990 |title=Table of Isotopes decay data |url=http://ie.lbl.gov/toi/nuclide.asp?iZA=870223 |publisher=Brookhaven National Laboratory |accessdate=2007-04-04 |deadurl=yes |archiveurl=https://web.archive.org/web/20061031212436/http://ie.lbl.gov/toi/nuclide.asp?iZA=870223 |archivedate=2006-10-31 }}</ref>鈁-223在出現於自然[[衰變鏈]]之前原本被稱為'''[[actinium]] K'''。

鈁-221的半衰期為4.8分鐘。<ref name="CRC2006P180" />它是[[錼衰變系]]的第九個產物，是錒-225的子同位素。<ref name="nostrand332" />鈁-221會再α衰變成砹-217（衰變能量為6.457&nbsp;MeV）。<ref name="CRC2006P180" />錼衰變系從[[錼]]-237開始，一直到砹-217都只有唯一的衰變途徑，因此鈁-221是唯一位在主要衰變途徑中的鈁同位素，惟自然界中的錼衰變系早已衰變殆盡，現時地殼中的錼衰變系初始同位素錼-237主要由[[鈾-238]]發生{{le|核散裂|Nuclear spallation}}而痕量生成。<ref name="chain">{{cite book|title=Chemistry and Analysis of Radionuclides: Laboratory Techniques and Methodology|publisher=Wiley-VCH|pages=2–3|year=2011 | isbn = 978-3-527-32658-7 |first1=Jukka|last1=Lehto|first2=Xiaolin|last2=Hou}}</ref>

[[基態]]最不穩定的同位素是鈁-215，半衰期只有0.12[[微秒]]。它會α衰變為砹-211，能量為9.54&nbsp;MeV。<ref name="CRC2006P180" />