# 11.6 Nuclear decay and conservation laws

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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, ${}^{\text{60}}\text{Co}$ is unstable and decays directly to ${}^{\text{60}}\text{Ni}$ , which is stable. Others, such as ${}^{\text{238}}\text{U}$ , 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 ${}^{\text{238}}\text{U}$ is of particular interest, since it produces the radioactive isotopes ${}^{\text{226}}\text{Ra}$ and ${}^{\text{210}}\text{Po}$ , which the Curies first discovered (see [link] ). Radon gas is also produced ( ${}^{\text{222}}\text{Rn}$ 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 ${}^{\text{238}}\text{U}$ and can be inhaled. The decay of radon and its daughters produces internal damage. The ${}^{\text{238}}\text{U}$ decay series ends with ${}^{\text{206}}\text{Pb}$ , a stable isotope of lead.

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

## Alpha decay

In alpha decay    , a ${}^{4}\text{He}$ 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 $\alpha$ decay is shown in [link] for ${}^{\text{238}}\text{U}$ . Another nuclide that undergoes $\alpha$ decay is ${}^{\text{239}}\text{Pu}$ . The decay equations for these two nuclides are

${}^{\text{238}}\text{U}\to {}^{\text{234}}{\text{Th}}_{\text{92}}^{\text{234}}+{}^{4}\text{He}$

and

${}^{\text{239}}\text{Pu}\to {}^{\text{235}}\text{U}+{}^{4}\text{He}.$

anyone know any internet site where one can find nanotechnology papers?
research.net
kanaga
Introduction about quantum dots in nanotechnology
what does nano mean?
nano basically means 10^(-9). nanometer is a unit to measure length.
Bharti
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
absolutely yes
Daniel
how to know photocatalytic properties of tio2 nanoparticles...what to do now
it is a goid question and i want to know the answer as well
Maciej
Abigail
for teaching engĺish at school how nano technology help us
Anassong
Do somebody tell me a best nano engineering book for beginners?
there is no specific books for beginners but there is book called principle of nanotechnology
NANO
what is fullerene does it is used to make bukky balls
are you nano engineer ?
s.
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.
Tarell
what is the actual application of fullerenes nowadays?
Damian
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.
Tarell
what is the Synthesis, properties,and applications of carbon nano chemistry
Mostly, they use nano carbon for electronics and for materials to be strengthened.
Virgil
is Bucky paper clear?
CYNTHIA
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
NANO
so some one know about replacing silicon atom with phosphorous in semiconductors device?
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.
Harper
Do you know which machine is used to that process?
s.
how to fabricate graphene ink ?
for screen printed electrodes ?
SUYASH
What is lattice structure?
of graphene you mean?
Ebrahim
or in general
Ebrahim
in general
s.
Graphene has a hexagonal structure
tahir
On having this app for quite a bit time, Haven't realised there's a chat room in it.
Cied
what is biological synthesis of nanoparticles
what's the easiest and fastest way to the synthesize AgNP?
China
Cied
types of nano material
I start with an easy one. carbon nanotubes woven into a long filament like a string
Porter
many many of nanotubes
Porter
what is the k.e before it land
Yasmin
what is the function of carbon nanotubes?
Cesar
I'm interested in nanotube
Uday
what is nanomaterials​ and their applications of sensors.
how did you get the value of 2000N.What calculations are needed to arrive at it
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