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  • Define and discuss nuclear decay.
  • State the conservation laws.
  • Explain parent and daughter nucleus.
  • Calculate the energy emitted during nuclear decay.

Nuclear decay    has provided an amazing window into the realm of the very small. Nuclear decay gave the first indication of the connection between mass and energy, and it revealed the existence of two of the four basic forces in nature. In this section, we explore the major modes of nuclear decay; and, like those who first explored them, we will discover evidence of previously unknown particles and conservation laws.

Some nuclides are stable, apparently living forever. Unstable nuclides decay (that is, they are radioactive), eventually producing a stable nuclide after many decays. We call the original nuclide the parent    and its decay products the daughters . Some radioactive nuclides decay in a single step to a stable nucleus. For example, 60 Co size 12{"" lSup { size 8{"60"} } "Co"} {} is unstable and decays directly to 60 Ni size 12{"" lSup { size 8{"60"} } "Ni"} {} , which is stable. Others, such as 238 U size 12{"" lSup { size 8{"238"} } U} {} , decay to another unstable nuclide, resulting in a decay series    in which each subsequent nuclide decays until a stable nuclide is finally produced. The decay series that starts from 238 U size 12{"" lSup { size 8{"238"} } U} {} is of particular interest, since it produces the radioactive isotopes 226 Ra size 12{"" lSup { size 8{"226"} } "Ra"} {} and 210 Po size 12{"" lSup { size 8{"210"} } "Po"} {} , which the Curies first discovered (see [link] ). Radon gas is also produced ( 222 Rn size 12{"" lSup { size 8{"222"} } "Rn"} {} in the series), an increasingly recognized naturally occurring hazard. Since radon is a noble gas, it emanates from materials, such as soil, containing even trace amounts of 238 U size 12{"" lSup { size 8{"238"} } U} {} and can be inhaled. The decay of radon and its daughters produces internal damage. The 238 U size 12{"" lSup { size 8{"238"} } U} {} decay series ends with 206 Pb size 12{"" lSup { size 8{"206"} } "Pb"} {} , a stable isotope of lead.

A graph is shown in which decay of alpha and beta is shown. Also half lives of each isotope are shown. Uranium decays in one mode but some isotopes decay by more than one mode. Finally a stable isotope of lead results.
The decay series produced by 238 U size 12{"" lSup { size 8{"238"} } U} {} , the most common uranium isotope. Nuclides are graphed in the same manner as in the chart of nuclides. The type of decay for each member of the series is shown, as well as the half-lives. Note that some nuclides decay by more than one mode. You can see why radium and polonium are found in uranium ore. A stable isotope of lead is the end product of the series.

Note that the daughters of α size 12{α} {} decay shown in [link] always have two fewer protons and two fewer neutrons than the parent. This seems reasonable, since we know that α size 12{α} {} decay is the emission of a 4 He size 12{"" lSup { size 8{4} } "He"} {} nucleus, which has two protons and two neutrons. The daughters of β size 12{β} {} decay have one less neutron and one more proton than their parent. Beta decay is a little more subtle, as we shall see. No γ size 12{γ} {} decays are shown in the figure, because they do not produce a daughter that differs from the parent.

Alpha decay

In alpha decay    , a 4 He size 12{"" lSup { size 8{4} } "He"} {} nucleus simply breaks away from the parent nucleus, leaving a daughter with two fewer protons and two fewer neutrons than the parent (see [link] ). One example of α size 12{α} {} decay is shown in [link] for 238 U size 12{"" lSup { size 8{"238"} } U} {} . Another nuclide that undergoes α size 12{α} {} decay is 239 Pu size 12{"" lSup { size 8{"239"} } "Pu"} {} . The decay equations for these two nuclides are

238 U 234 Th 92 234 + 4 He


239 Pu 235 U + 4 He . size 12{"" lSup { size 8{"239"} } "Pu" rightarrow "" lSup { size 8{"235"} } U+"" lSup { size 8{4} } "He"} {}
The image shows conditions before and after alpha decay. Before alpha decay the nucleus is labeled parent and after decay the nucleus is labeled daughter.
Alpha decay is the separation of a 4 He size 12{"" lSup { size 8{4} } "He"} {} nucleus from the parent. The daughter nucleus has two fewer protons and two fewer neutrons than the parent. Alpha decay occurs spontaneously only if the daughter and 4 He size 12{"" lSup { size 8{4} } "He"} {} nucleus have less total mass than the parent.

Questions & Answers

anyone know any internet site where one can find nanotechnology papers?
Damian Reply
Introduction about quantum dots in nanotechnology
Praveena Reply
what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
Damian Reply
absolutely yes
how to know photocatalytic properties of tio2 nanoparticles...what to do now
Akash Reply
it is a goid question and i want to know the answer as well
characteristics of micro business
for teaching engĺish at school how nano technology help us
Do somebody tell me a best nano engineering book for beginners?
s. Reply
there is no specific books for beginners but there is book called principle of nanotechnology
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
what is the actual application of fullerenes nowadays?
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
Mostly, they use nano carbon for electronics and for materials to be strengthened.
is Bucky paper clear?
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Do you know which machine is used to that process?
how to fabricate graphene ink ?
for screen printed electrodes ?
What is lattice structure?
s. Reply
of graphene you mean?
or in general
in general
Graphene has a hexagonal structure
On having this app for quite a bit time, Haven't realised there's a chat room in it.
what is biological synthesis of nanoparticles
Sanket Reply
what's the easiest and fastest way to the synthesize AgNP?
Damian Reply
types of nano material
abeetha Reply
I start with an easy one. carbon nanotubes woven into a long filament like a string
many many of nanotubes
what is the k.e before it land
what is the function of carbon nanotubes?
I'm interested in nanotube
what is nanomaterials​ and their applications of sensors.
Ramkumar Reply
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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Source:  OpenStax, Concepts of physics with linear momentum. OpenStax CNX. Aug 11, 2016 Download for free at http://legacy.cnx.org/content/col11960/1.9
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