Editing Neutron emission (section)

==Spontaneous neutron emission==
As a consequence of the [[Pauli exclusion principle]], nuclei with an excess of protons or neutrons have a higher average energy per nucleon. Nuclei with a sufficient excess of neutrons have a greater energy than the combination of a free neutron and a nucleus with one less neutron, and therefore can decay by neutron emission. Nuclei which can decay by this process are described as lying beyond the [[neutron drip line]].

Two examples of isotopes that emit neutrons are [[beryllium-13]] (decaying to [[beryllium-12]] with a mean life {{val|2.7|e=-21|ul=s}}) and [[helium-5]] ([[helium-4]], {{val|7|e=-22|u=s}}).<ref>{{cite web|url=http://education.jlab.org/glossary/neutron_emission.html |title=Neutron Emission|format=webpage |access-date=2014-10-30}}</ref>

In tables of nuclear decay modes, neutron emission is commonly denoted by the abbreviation ''n''.

:{| class="wikitable" align="left"
|+ Neutron emitters to the left of lower dashed line (see also: [[Table of nuclides]])
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{{Isotones|-2_0}}
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{{Isotones|12_0}}
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{{Isotones|13_0}}
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{{Isotones|14_0}}
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{{clear}}

=== Double neutron emission ===
Some neutron-rich isotopes decay by the emission of two or more neutrons. For example, hydrogen-5 and helium-10 decay by the emission of two neutrons, hydrogen-6 by the emission of 3 or 4 neutrons, and hydrogen-7 by emission of 4 neutrons.