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<img src="../../media/nuclear/nuctitle.gif" alt="Nuclear Chemistry" width="271" height="91">
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<p>Radioactive elements are elements that do not have a stable nucleus.
These elements give off particles and/or rays to change their nucleus and
become a stable element. Some lightweight isotopes are radioactive but, all
elements that have an atomic number greater
than 82 are radioactive. The process of changing the nucleus to a stable
one is called radioactive decay.
<!--mstheme--></font><!--msthemelist--><table border="0" cellpadding="0" cellspacing="0" width="100%">
<!--msthemelist--><tr><td valign="baseline" width="42"><img src="../../../../_themes/education/blbull1.gif" width="15" height="15" hspace="13"></td><td valign="top" width="100%"><!--mstheme--><a href="#nuc">Nuclear Equations</a>
<!--msthemelist--><tr><td valign="baseline" width="42"><img src="../../../../_themes/education/blbull1.gif" width="15" height="15" hspace="13"></td><td valign="top" width="100%"><!--mstheme--><a href="#decay">Radioactive Decay</a>
<!--msthemelist--><tr><td valign="baseline" width="42"><img src="../../../../_themes/education/blbull1.gif" width="15" height="15" hspace="13"></td><td valign="top" width="100%"><!--mstheme--><a href="#bomb">Nuclear Bombardment Reactions</a>
<!--msthemelist--><tr><td valign="baseline" width="42"><img src="../../../../_themes/education/blbull1.gif" width="15" height="15" hspace="13"></td><td valign="top" width="100%"><!--mstheme--><a href="#half">Half-Life</a>
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<img src="../../media/nuclear/nuclearequ.jpg" alt="Nuclear Equations" width="320" height="66">
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<p>Nuclear notations are used to represent the decay of one element into
another. The generic formula for a radioactive element is as follows:
<center>
<p><img src="../../media/nuclear/gen.gif" alt="Generic Equation" width="239" height="106">
</center>
<p>Some examples of nuclear decay equations are:
<center>
<p><img src="../../media/nuclear/ex_1.gif" alt="example one" width="280" height="54">
<p><img src="../../media/nuclear/ex_2.gif" alt="example two" width="243" height="62">
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<img src="../../media/nuclear/radioactive.jpg" alt="Radioactive Decay" width="328" height="55">
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<p>There are three types of natural radioactive decay. They are
alpha emisson, beta emission, and gamma
emission. Alpha emission results in releasing an alpha particle. An alpha
particle has two protons and two neutrons, so it has a positive
charge. (Since it has two
protons it is a helium nucleus.) It is written in equations like this:
<p><img src="../../media/nuclear/alpha.gif" alt="alpha particle" width="52" height="42">
<p>Beta emission is when a high speed electron (negative charge) leaves the
nucleus. Beta emission occurs in elements with more neutons than
protons, so a neutron splits into a proton and an electron. The proton
stays in the nucleus and the electron is emitted. Negative electrons are
represented as follows:
<p><img src="../../media/nuclear/electron.gif" alt="electron" width="38" height="44">
<p>Gamma Emission is when an excited nucleus gives off a ray in the gamma
part of the spectrum. A gamma ray has no mass and no charge. This often
occurs in radioactive elements because the
other types of emission can result in an excited nucleus. Gamma rays are
represented with the following symbol.
<p><img src="../../media/nuclear/gamma.gif" alt="gamma ray symbol" width="41" height="42">
<p><h3><!--mstheme--><font color="#6666CC">The two types of artificial radiation are positron emission and electron
capture.<!--mstheme--></font></h3>
<p>Positron emission involves a particle that has the same mass as an electron
but a positive charge. The particle is released from the nucleus.
<p><img src="../../media/nuclear/positron.gif" alt="Positron" width="38" height="44">
<p>Electron capture is when an unstable nucleus grabs an electron from
its inner shell to help stabilize the nucleus. The electrons combine with
a proton to form a neutron which stays in the nucleus.
<p><img src="../../media/nuclear/ec.gif" alt="Electron Capture" width="260" height="58">
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<a href="#nuc">Nuclear Equations</a> |
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<a href="#bomb">Nuclear Bombardment Reactions</a> |
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<img src="../../media/nuclear/nuclearbomb.jpg" alt="Nuclear Bombardment Reactions" width="422" height="103">
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<p>Bombardment reactions involve the nucleus of the atom being bombarded
(hence the name) with particles from the nucleus or an entire nucleus.
Examples of the particles are neutrons and alpha particles. These reactions
usually give off a different particle than the one that they were bombarded
with. Here is an example equation for a bombardment reaction.
<center>
<p><img src="../../media/nuclear/ex_3.gif" alt="bombardment example" width="335" height="55">
</center>
<p>Particle accelerators are where most of the bombarding takes place. The
accelerators move the particles toward each other at great speeds, to
overcome the repulsive forces.
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<img src="../../media/nuclear/halflife.jpg" alt="Half-Life" width="198" height="74">
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<p>No one can say for sure when a particular nucleus will decay but one can
predict how many in a given sample will decay over time. Radioactive elements have
a half-life. The half life of any given element is the time that is required
for one half of the sample to decay. So if you have 10
grams of a radioactive element, after one half-life there will be 5 grams of
the radioactive element left. After another half-life, there will be 2.5 g of the original element left, after another half-life, 1.25 g will be left.
The equation for half-life calculations is as
follows:
<p><img src="../../media/nuclear/halflife/halfequ.gif" alt="Half life equation" width="212" height="78">
<!--mstheme--></font><!--msthemelist--><table border="0" cellpadding="0" cellspacing="0" width="100%">
<!--msthemelist--><tr><td valign="baseline" width="42"><img src="../../../../_themes/education/blbull1.gif" width="15" height="15" hspace="13"></td><td valign="top" width="100%"><!--mstheme-->A<sub>E</sub> is the amount of substance left
<!--msthemelist--><tr><td valign="baseline" width="42"><img src="../../../../_themes/education/blbull1.gif" width="15" height="15" hspace="13"></td><td valign="top" width="100%"><!--mstheme-->A<sub>0</sub> is the original amount of substance
<!--msthemelist--><tr><td valign="baseline" width="42"><img src="../../../../_themes/education/blbull1.gif" width="15" height="15" hspace="13"></td><td valign="top" width="100%"><!--mstheme-->t is the elasped time
<!--msthemelist--><tr><td valign="baseline" width="42"><img src="../../../../_themes/education/blbull1.gif" width="15" height="15" hspace="13"></td><td valign="top" width="100%"><!--mstheme-->t<sub>1/2</sub> is the half-life of the substance
<!--msthemelist--></table><!--mstheme-->
<p>Other variations on the half-life equation are as follows:
<p><img src="../../media/nuclear/halflife/halftime.gif" alt="time equation" width="229" height="104">
<p><img src="../../media/nuclear/halflife/halflife.gif" alt="half life equation" width="224" height="113">
<p>An example problem is if you originally had 157 grams of carbon-14 and the
half-life of carbon-14 is 5730 years, how much would there be after 2000 years?
<p><img src="../../media/nuclear/halflife/ex_1.gif" alt="example one" width="222" height="63">
<p>There would be 123 grams left.
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