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need to protect themselves from welding sparks, which are heated metal particles that fly off the welding surface.]] In the physical sciences, a particle (or corpuscule in older texts) is a small object to which can be ascribed several physical or chemical properties such as volume or mass. The term 'particle' is rather general in meaning, and is refined as needed by various scientific fields. Something that is composed of particles may be referred to as being particulate.

Conceptual properties

. This figure could represent the movement of atoms in a gas, people in crowds or stars in the night sky.]] The concept of particles is particularly useful when modelling nature, as the full treatment of many phenomena can be complex and also involve difficult computation.


are so large that stars can be considered particles relative to them]] The term "particle" is usually applied differently to three classes of sizes. The term macroscopic particle, usually refers to particles much larger than atoms and molecules. These are usually abstracted as point-like particles, even though they have volumes, shapes, structures, etc. Examples of macroscopic particles would include powder, dust, sand, pieces of debris during a car accident, or even objects as big as the stars of a galaxy. Another type, microscopic particles usually refers to particles of sizes ranging from atoms to molecules, such as carbon dioxide, nanoparticles, and colloidal particles. These particles are studied in chemistry, as well as atomic and molecular physics. The smallest of particles are the subatomic particles, which refer to particles smaller than atoms. Because of their extremely small size, the study of microscopic and subatomic particles fall in the realm of quantum mechanics. They will exhibit phenomena demonstrated in the particle in a box model,


is composed of three quarks.]] Particles can also be classified according to composition. Composite particles refer to particles that have – that is particles which are made of other particles.


Both elementary (such as muons) and composite particles (such as uranium nuclei), are known to undergo particle decay. Those that do not are called stable particles, such as the electron or a helium-4 nucleus. The lifetime of stable particles can be either infinite or large enough to hinder attempts to observe such decays. In the latter case, those particles are called " observationally stable". In general, a particle decays from a high- energy state to a lower-energy state by emitting some form of radiation, such as the emission of photons.

N-body simulation

In computational physics, N-body simulations (also called N-particle simulations) are simulations of dynamical systems of particles under the influence of certain conditions, such as being subject to gravity. N refers to the number of particles considered. As simulations with higher N are more computationally intensive, systems with large numbers of actual particles will often be approximated to a smaller number of particles, and simulation algorithms need to be optimized through various methods.

Distribution of particles

Colloidal particles are the components of a colloid. A colloid is a substance microscopically dispersed evenly throughout another substance.

See also


Further reading

  • {{cite web
|date=23 July 2010 |title=What is a particle? |url=http://perc.ufl.edu/particle.asp |publisher= University of Florida, Particle Engineering Research Center }}
  • {{cite book
|author=D. J. Griffiths |year=2008 |edition=2nd |title=Introduction to Particle Physics |publisher= Wiley-VCH |isbn=978-3-527-40601-2 }}
  • {{cite book
|author1=M. Alonso |author2=E. J. Finn |year=1967 |chapter=Dynamics of a particle |title=Fundamental University Physics, Volume 1 |publisher= Addison-Wesley |lccn=66010828 }}
  • {{cite book
|author1=M. Alonso |author2=E. J. Finn |year=1967 |chapter=Dynamics of a system of particles |title=Fundamental University Physics, Volume 1 |publisher= Addison-Wesley |lccn=66010828 }}
  • {{cite web
|author=S. Segal |year=n.d. |title=What is a Particle? - Definition & Theory |url=http://study.com/academy/lesson/what-is-a-particle-definition-theory-quiz.html |url-access=subscription |work=High School Chemistry: Help and Review |at=Chapter 4, Lesson 6 |publisher=Study.com }}
  • {{cite web
|year=2015 |title=A basic guide to particle characterization |url=http://www.cif.iastate.edu/sites/default/files/uploads/Other_Inst/Particle%20Size/Particle%20Characterization%20Guide.pdf |publisher= Malvern Instruments }}
"green air" © 2007 - Ingo Malchow, Webdesign Neustrelitz
This article based upon the http://en.wikipedia.org/wiki/particle, the free encyclopaedia Wikipedia and is licensed under the GNU Free Documentation License.
Further informations available on the list of authors and history: http://en.wikipedia.org/w/index.php?title=particle&action=history
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