Neutron: Difference between revisions
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A '''neutron''' is | A '''neutron''' is a subatomic particle that normally is part of the [[nucleus]] of a [[chemical element]]. When free (not bound to a nucleus), a neutron can have important physical, chemical, and biological<ref name=WHOion>{{citation | ||
| author = World Health Organization | | author = World Health Organization | ||
| title = Ionizing Radiation | | title = Ionizing Radiation | ||
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The mass ''m''<sub>n</sub> of a neutron<ref> Value retrieved from [http://physics.nist.gov/cgi-bin/cuu/Value?mn NIST] on October 1, 2008</ref> is close to, but not equal to, the mass of a [[proton]]: | The mass ''m''<sub>n</sub> of a neutron<ref> Value retrieved from [http://physics.nist.gov/cgi-bin/cuu/Value?mn NIST] on October 1, 2008</ref> is close to, but not equal to, the mass of a [[proton]]: | ||
:''m''<sub>n</sub> = 1.674 927 211 × 10<sup>−27</sup> kg . | :''m''<sub>n</sub> = 1.674 927 211 × 10<sup>−27</sup> kg. | ||
The neutron consists of three [[quarks]]. A free neutron shows beta decay, breaking down into a proton, an [[electron]], and an [[antineutrino]]. Because it disintegrates, the free neutron does not exist in nature. Neutrons do not carry electric charge, they pass unhindered through the electrical fields within liquids and solids. | |||
==History== | ==History== | ||
The existence of the neutron was discovered, in 1932, by Sir [[James Chadwick]], who received the 1935 [[Nobel Prize]] in Physics for his work. A repeatable experimental demonstration of the existence of the neutron solved a number of then-outstanding problems in physics, although the applications and significance of neutrons were in their infancy.<ref name=PhysLabNeutron>{{citation | The existence of the neutron was discovered, in 1932, by Sir [[James Chadwick]], who received the 1935 [[Nobel Prize]] in Physics for his work. A repeatable experimental demonstration of the existence of the neutron solved a number of then-outstanding problems in physics, although the applications and significance of neutrons were in their infancy.<ref name=PhysLabNeutron>{{citation | ||
Revision as of 07:29, 1 October 2008
Template:TOC-right A neutron is a subatomic particle that normally is part of the nucleus of a chemical element. When free (not bound to a nucleus), a neutron can have important physical, chemical, and biological[1] effects.
The mass mn of a neutron[2] is close to, but not equal to, the mass of a proton:
- mn = 1.674 927 211 × 10−27 kg.
The neutron consists of three quarks. A free neutron shows beta decay, breaking down into a proton, an electron, and an antineutrino. Because it disintegrates, the free neutron does not exist in nature. Neutrons do not carry electric charge, they pass unhindered through the electrical fields within liquids and solids.
History
The existence of the neutron was discovered, in 1932, by Sir James Chadwick, who received the 1935 Nobel Prize in Physics for his work. A repeatable experimental demonstration of the existence of the neutron solved a number of then-outstanding problems in physics, although the applications and significance of neutrons were in their infancy.[3]
Role in the nucleus
Health effects
From the biological standpoint, neutrons are indirectly ionizing. [1]
References
- ↑ 1.0 1.1 World Health Organization, Ionizing Radiation
- ↑ Value retrieved from NIST on October 1, 2008
- ↑ Colwell, Catharine H., Famous Experiments: The Discovery of the Neutron, PhysicsLab