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Any of various particles of matter smaller than a hydrogen atom, including the elementary particles and hadrons.
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
One of the basic units of which atoms and all matter are made. Protons, neutrons and electrons are subatomic particles.
Did You Know? Until the 20th century, scientists thought that atoms were the smallest units of matter. This view started to change following some experiments in the late 1800s involving electrical discharges. By the early 1900s it was clear that these discharges were composed of a new kind of particle, one that was much lighter than an atom of the lightest chemical element, hydrogen. These particles were named electrons. It was further learned that atoms themselves contained electrons; the electron thus became the first known subatomic particle. Since electrons have negative electrical charge, but the atoms containing them are neutral in charge, researchers believed that atoms must also contain positively-charged particles that balanced the negatively-charged electrons. This idea, together with research into radioactivity, led Ernest Rutherford to the discovery of the atomic nucleus in 1911. Rutherford saw the nucleus as the home of these positively-charged particles (now called protons). Further experiments on radioactivity showed, by 1932, that the nucleus also contained a third kind of particle, the neutron. While electrons, protons, and neutrons are the most familiar subatomic particles, they are not the only ones: dozens more have since been identified. Scientists now think that many subatomic particles are themselves made up of smaller units called elementary particles, such as neutrinos and quarks.
The American Heritage® Student Science Dictionary, Second Edition. Copyright © 2014 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
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|Noun||1.||subatomic particle - a body having finite mass and internal structure but negligible dimensions|
virion - (virology) a complete viral particle; nucleic acid and capsid (and a lipid envelope in some viruses)
alpha particle - a positively charged particle that is the nucleus of the helium atom; emitted from natural or radioactive isotopes
beta particle - a high-speed electron or positron emitted in the decay of a radioactive isotope
body - an individual 3-dimensional object that has mass and that is distinguishable from other objects; "heavenly body"
boson - any particle that obeys Bose-Einstein statistics but not the Pauli exclusion principle; all nuclei with an even mass number are bosons
deuteron - the nucleus of deuterium; consists of one proton and one neutron; used as a bombarding particle in accelerators
elementary particle, fundamental particle - (physics) a particle that is less complex than an atom; regarded as constituents of all matter
fermion - any particle that obeys Fermi-Dirac statistics and is subject to the Pauli exclusion principle
ion - a particle that is electrically charged (positive or negative); an atom or molecule or group that has lost or gained one or more electrons
magnetic monopole - a hypothetical particle with a single magnetic pole instead of the usual two
micelle - an electrically charged particle built up from polymeric molecules or ions and occurring in certain colloidal electrolytic solutions like soaps and detergents
prion - (microbiology) an infectious protein particle similar to a virus but lacking nucleic acid; thought to be the agent responsible for scrapie and other degenerative diseases of the nervous system
virino - (microbiology) a hypothetical infectious particle thought to be the cause of scrapie and other degenerative diseases of the central nervous system; consists of nucleic acid in a protective coat of host cell proteins
scintilla - a sparkling glittering particle
superstring - a hypothetical particle that is the elementary particle in a theory of space-time
thermion - an electrically charged particle (electron or ion) emitted by a substance at a high temperature
Based on WordNet 3.0, Farlex clipart collection. © 2003-2012 Princeton University, Farlex Inc.