编辑“︁铷”︁（章节）

===同位素===
{{Main|銣的同位素}}
自然界中的銣元素由兩種同位素組成：[[穩定同位素|穩定]]的<sup>85</sup>Rb（佔72.2%）以及長壽[[放射性同位素]]<sup>87</sup>Rb（佔27.8%），故銣是一種[[單一同位素元素]]（即只有一種穩定同位素）。<ref name="Audi">{{Cite journal| last = Audi |first = Georges |title = The NUBASE Evaluation of Nuclear and Decay Properties |journal = Nuclear Physics A |volume = 729| issue = 1 |pages = 3–128| publisher = Atomic Mass Data Center |year = 2003| doi=10.1016/j.nuclphysa.2003.11.001| bibcode=2003NuPhA.729....3A| last2 = Bersillon| first2 = O.| last3 = Blachot| first3 = J.| last4 = Wapstra| first4 = A.H.}}</ref><sup>87</sup>Rb的存在使得自然界中的銣具有放射性，比活性約為670 [[貝克勒爾|Bq]]/g。這樣的輻射水平可以在110天內於照相[[底片]]上留下影像。<ref>{{cite journal | last1 = Strong | first1 = W. W. | title = On the Possible Radioactivity of Erbium, Potassium and Rubidium | url = https://archive.org/details/sim_physical-review_1909-08_29_2/page/170 | journal = Physical Review | series = Series I | volume = 29 | issue = 2 | pages = 170–173 | year = 1909 | doi = 10.1103/PhysRevSeriesI.29.170 |bibcode = 1909PhRvI..29..170S }}</ref><ref>{{cite book | url = http://books.google.com/books?id=6khCAQAAIAAJ | pages = 4–25 | title = CRC handbook of chemistry and physics: a ready-reference book of chemical and physical data | isbn = 978-0-8493-0476-7 | author1 = Lide, David R | author2 = Frederikse, H. P. R | date = June 1995 | access-date = 2014-12-17 | archive-date = 2013-11-03 | archive-url = https://web.archive.org/web/20131103052935/http://books.google.com/books?id=6khCAQAAIAAJ | dead-url = no }}</ref>除<sup>85</sup>Rb和<sup>87</sup>Rb之外，還有30種人造的銣同位素，它們都具有放射性，且[[半衰期#物理學|半衰期]]都在3個月以內。<ref>{{cite web |url=http://www.nucleonica.net/unc.aspx |title=Universal Nuclide Chart |publisher=nucleonica |registration=yes |accessdate=2017-01-03 |archive-date=2017-02-19 |archive-url=https://web.archive.org/web/20170219043412/http://www.nucleonica.net/unc.aspx |dead-url=no }}</ref>

銣-87的[[半衰期#物理學|半衰期]]為{{val|48.8|e=9}}年，這是[[宇宙年齡]]{{val|13.798|e=9}}年的三倍有餘。<ref name='planck_cosmological_parameters'>{{cite journal | arxiv=1303.5076 | title=Planck 2013 results. XVI. Cosmological parameters | author=Planck collaboration | journal=Submitted to Astronomy & Astrophysics | year=2013 | bibcode=2014A&A...571A..16P | last2=Ade | first2=P. A. R. | last3=Aghanim | first3=N. | last4=Armitage-Caplan | first4=C. | last5=Arnaud | first5=M. | last6=Ashdown | first6=M. | last7=Atrio-Barandela | first7=F. | last8=Aumont | first8=J. | last9=Baccigalupi | first9=C. |displayauthors=8 | volume=1303 | pages=5076 | doi=10.1051/0004-6361/201321591}}</ref>它是一種[[原生核素]]，在地球形成時便已存在。在[[礦物]]中，銣常會代替[[鉀]]元素的位置，所以其分佈廣泛。<sup>87</sup>Rb在釋放一個負[[β粒子]]之後，會衰變成穩定的[[鍶|<sup>87</sup>Sr]]，這可以用於[[放射性定年法|測定岩石的年齡]]。在地球內部的[[分級結晶]]過程中，鍶會集中在[[斜長石]]中，留下處於液態的銣。因此，在殘餘[[岩漿]]中銣對鍶的比例會隨時間增加，經[[活成分異作用]]形成銣/鍶比例較高的岩石。[[偉晶岩]]中的銣/鍶比例最高（10以上）。如果可以測得或推算出最初的鍶含量，那麼通過測量目前銣和鍶的含量以及<sup>87</sup>Sr/<sup>86</sup>Sr比例，就可以算出該岩石樣本的年齡。這一年齡只有在岩石不曾受變動的情況下才等於真實的年齡值<!-- 參見[[銣鍶定年法]]（[[rubidium-strontium dating]]） -->。<ref>{{Cite book |url = http://books.google.com/?id=k90iAnFereYC&pg=PA162 |chapter = Rubidium-Strontium Dating |title = Isotopes in the Earth Sciences |first1 = H. -G. |last1 = Attendorn |first2 = Robert |last2 = Bowen |publisher = Springer |year = 1988 |isbn = 978-0-412-53710-3| pages = 162–165}}</ref><ref>{{Cite book |url =http://books.google.com/?id=cYWNAZbPhMYC&pg=PA383 |title = Essentials of geochemistry |first1 =John Victor |last1 =Walther |publisher =Jones & Bartlett Learning| year = 1988 2009 |isbn =978-0-7637-5922-3| chapter =Rubidium-Strontium Systematics| pages = 383–385}}</ref>

銣-82是銣的人造同位素之一，可經鍶-82的[[電子捕獲]]衰變過程產生，反應的半衰期為25.36天。銣-82會再經[[正電子發射]]衰變為穩定的[[氪]]-82，半衰期為76秒。<ref name="Audi"/>