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particle
subject			fact

particle	obeys uncertainty principle
	has frequency inversely proportional to the wavelength
	has wavelength inversely proportional to its momentum
	has charge
	has mass
	has definition Fundamental unit of matter and energy. All may be classed as fermions, which have half-integral spin and obey the exclusion principle, and bosons, which have integral spin and do not obey the exclusion principle. The term particle is metaphoric, in that all subatomic particles also evince aspects of wave-like behavior.
	is a kind of natural object
physical object	has location or center of gravity
	has angular momentum
	has velocity
	has momentum
	has temperature
	has volume
	has extent
	has material

Kinds of particle :

• antiparticle (5 kinds, 39 facts) - An elementary particle of opposite charge but otherwise identical to its partner. Most of the observable universe consists of particles and matter, as opposed to antiparticles and antimatter., For every known type of particle, there exists an antiparticle with exactly the same mass, but with the opposite electric charge. When a particle and its antiparticle come together, they can always annihilate to form gamma rays. The antiparticle of an electrically neutral particle is sometimes the same as the original particle (e.g., photons) and sometimes it is distinct (e.g., neutrons)., Particles predicted by combining the theories of special relativity and quantum mechanics. For each particle, there must exist an antiparticle with the opposite charge, magnetic moment and other internal quantum numbers (e.g., lepton number, baryon number, strangeness, charm, etc.), but with the same mass, spin and lifetime. Note that certain neutral particles (such as the photon and π⁰) are their own antiparticles., Atomic particles that have the same mass as, but opposite charge and orbital direction to, an ordinary particle. Thus, instead of negatively charged electrons, atoms of antimatter have positrons. A quantity of antimatter coming into contact with matter would "cancel out" - annihilate, with total conversion of mass to energy - an exact proportion of matter corresponding to the original quantity of antimatter, provided that the elements in the matter also corresponded with the "elements" in the antimatter, i.e., that the atoms were equivalent but opposite., Particles with identical mass and spin as those of ordinary matter, but with opposite charge. Antimatter has been produced experimentally, but little of it is found in nature. Why this should be so is one of the questions that must be answered by any adequate theory of the early universe.
• boson (63 kinds, 245 facts) - A particle which does not obey Pauli's exclusion principle. It is denoted by an integer (or zero) spin., Any particle with integer spin: 0, h bar, 2h bar etc., A class of elementary particles whose spin is an integer multiple of a fundamental quantized value. The major function of bosons is to mediate the fundamental forces. The best-known boson is the photon., A subatomic particle whose spin is an integral multiple of h bar (cf. fermion). Bosons include the photons, the pions, the gravitons, and all Bose-Einstein nuclei. Boson number is not conserved., Elementary particles with integer spin that do not obey the Pauli exclusion principle. They include the photons and the W and Z particles, carriers of the electromagnetic and the electroweak forces respectively., Elementary particles that have integral spins. Force particles such as the photon, gluon, and vector bosons are all bosons. But note that there can also exist composite particles formed out of collections of fermions such as a helium atom-which act collectively as bosons., A particle, or pattern of string vibration, with a whole number amount of spin; typically a messenger particle.
• charged particle (42 kinds, 186 facts) - A particle with non-zero charge
• element (349 kinds, 5084 facts) (atom) - Different elements are distinguished by the number of protons in their nuclei. All hydrogen atoms have one proton; all helium atoms have two protons; all oxygen atoms have eight protons., The smallest component of matter that retains its chemical properties. An atom consists of a nucleus and at least one electron., The building block of matter. The nucleus of an atom consists of one or more protons and may contain neutrons as well; any electrons surround the nucleus. The number of protons in the atom - the atomic number - determines the element., The fundamental unit of a chemical element. An atom consists of a nucleus, which may contain protons and neutrons, and electrons, which occupy shells that surround the nucleus and are centered on it.
• elementary particle (97 kinds, 416 facts) - A particle considered to be fundamental, i.e. not composite, a particle which cannot be separated into components
• fermion (38 kinds, 202 facts) - Any particle with half-integer spin: 1/2 h bar, 3/2 h bar, 5/2 h bar, etc. All fermions obey Pauli's exclusion principle., An elementary particle whose spin is a half-integral multiple of h/2π. Fermions include the baryons, the leptons and their antiparticles, and obey the Pauli exclusion principle (cf. boson)., A particle, or pattern of string vibration, with half a whole odd number amount of spin; typically a matter particle., Particle with half-integral spin. Fermions obey the exclusion principle, which says that no two fermions can exist in an atom in the same quantum state; in practice this restricts the number of electrons, which are fermions, permitted in each electron shell., Elementary particle with fractional spin. The proton, electron, neutron, and other elementary particles are all fermions.
• hypothetical particle (53 kinds, 232 facts)
• massless particle (47 kinds, 171 facts) - A particle with zero mass
• molecule (38 kinds, 110 facts) - The smallest unit of a chemical compound. A molecule is composed of two or more atoms, linked by interactions of their electrons.
• neutral particle (59 kinds, 226 facts) - A particle with zero charge
• radioactive particle (35 kinds, 408 facts) - A particle which can produce harmful radioactivity directly through its decay or by interacting with other particles.
• secondary cosmic ray (2 facts) - Atomic fragment - mainly muons - produced by collisions between primary cosmic rays and the molecules in Earth's atmosphere.
• virtual particle (1 kind, 7 facts) - A particle that exists for an extremely short time in an intermediate stage of a reaction or transition., Particles which take part in virtual processes. They are said to be "off mass-shell", meaning that the relation E² = p²c² + m₀² c⁴ does not hold., Particles that erupt from the vacuum momentarily; they exist on borrowed energy, consistent with the uncertainty principle, and rapidly annihilate, thereby repaying the energy loan., Quantum uncertainties in energy make it possible for virtual particles to be constantly created and annihilated during elementary particle interactions. Elementary particles are able to make use of these virtual particles within their interactions.