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{{Short description|Remaining nuclide left over from radioactive decay}}
{{More citations needed|date=December 2007}}
{{Nuclear physics}}

In [[nuclear physics]], a '''decay product''' (also known as a '''daughter product''', '''daughter isotope''', '''radio-daughter''', or '''daughter nuclide''') is the remaining [[nuclide]] left over from [[radioactive decay]]. Radioactive decay often proceeds via a sequence of steps ([[decay chain]]). For example, [[uranium-238|238U]] decays to [[thorium|234Th]] which decays to [[Isotopes of protactinium#Protactinium-234|234mPa]] which decays, and so on, to 206Pb (which is stable):

:<math chem>
\ce{^{238}U ->} \overbrace{ \underbrace\ce{^{234}Th}_\ce{daughter~of~^{238}U} \ce{->} \underbrace\ce{^{234\!m}Pa}_\ce{granddaughter~of~^{238}U} \ce{-> \cdots -> {^{206}Pb} }}^\ce{decay~products~of~^{238}U}
</math>

[[file:Thorium decay chain from lead-212 to lead-208.svg|thumb|left|upright|The decay chain from lead-212 down to lead-208, showing the intermediate decay products]]

In this example:
* 234Th, 234mPa,...,206Pb are the decay products of 238U.
* 234Th is the daughter of the parent 238U.
* 234mPa (234 [[nuclear isomer|metastable]]) is the granddaughter of 238U.
These might also be referred to as the daughter products of 238U.<ref>[http://www.gulflink.osd.mil/library/randrep/du/mr1018.7.gloss.html Glossary of Volume 7] {{Webarchive|url=https://web.archive.org/web/20170103181840/http://www.gulflink.osd.mil/library/randrep/du/mr1018.7.gloss.html |date=2017-01-03 }} (''Depleted Uranium'' — authors: Naomi H. Harley, Ernest C. Foulkes, Lee H. Hilborne, Arlene Hudson, and C. Ross Anthony) of ''A review of the scientific literature as it pertains to gulf war illnesses''.</ref>

Decay products are important in understanding radioactive decay and the management of [[radioactive waste]].

For elements above [[lead]] in [[atomic number]], the decay chain typically ends with an [[isotope]] of lead or [[bismuth]]. Bismuth itself decays to [[thallium]], but the decay is so slow as to be practically negligible.

In many cases, individual members of the decay chain are as radioactive as the parent, but far smaller in volume/mass. Thus, although uranium is not dangerously radioactive when pure, some pieces of naturally occurring [[Uraninite|pitchblende]] are quite dangerous owing to their [[radium-226]] content,<ref name=Ra226>{{cite journal |last=Peh |first=W. C. G. |title=The Discovery of Radioactivity and Radium |date=1996 |journal=Singapore Medical Journal |volume=37 |issue=6 |pages=627–630 |url=http://smj.sma.org.sg/3706/3706a16.pdf |pmid=9104065}}</ref> which is soluble and not a ceramic like the parent. Similarly, [[thorium]] [[gas mantle]]s are very slightly radioactive when new, but become more radioactive after only a few months of storage as the daughters of 232Th build up.

Although it cannot be predicted whether any given atom of a radioactive substance will decay at any given time, the decay products of a radioactive substance are extremely predictable. Because of this, decay products are important to scientists in many fields who need to know the quantity or type of the parent product. Such studies are done to measure pollution levels (in and around nuclear facilities) and for other matters.

== See also ==
* [[Decay chain]]

== References ==

{{Reflist}}

[[Category:Nuclear physics]]
[[Category:Nuclear chemistry]]

Decay product - Revision history

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