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In the physical sciences, a particle (or corpuscule in older texts) is a small localized object which can be described by several physical or chemical properties, such as volume, density, or mass. [ 1 ] [ 2 ] They vary greatly in size or quantity, from subatomic particles like the electron , to microscopic particles like atoms and molecules ...
Atoms are the smallest neutral particles into which matter can be divided by chemical reactions. An atom consists of a small, heavy nucleus surrounded by a relatively large, light cloud of electrons. An atomic nucleus consists of 1 or more protons and 0 or more neutrons. Protons and neutrons are, in turn, made of quarks.
The neutrino [a] was postulated first by Wolfgang Pauli in 1930 to explain how beta decay could conserve energy, momentum, and angular momentum ().In contrast to Niels Bohr, who proposed a statistical version of the conservation laws to explain the observed continuous energy spectra in beta decay, Pauli hypothesized an undetected particle that he called a "neutron", using the same -on ending ...
In addition to the classification by particle size, dispersions can also be labeled by the combination of the dispersed phase and the medium phase that the particles are suspended in. Aerosols are liquids dispersed in a gas, sols are solids in liquids, emulsions are liquids dispersed in liquids (more specifically a dispersion of two immiscible ...
[237] A 2011 study concluded that traffic exhaust is the single most serious preventable cause of heart attack in the general public, the cause of 7.4% of all attacks. [ 238 ] Particulate matter studies in Bangkok, Thailand from 2008 indicated a 1.9% increased risk of dying from cardiovascular disease, and 1.0% risk of all disease for every 10 ...
Besides being cheap and convenient, the wet chemical approach allows fine control of the particle's chemical composition. Even small quantities of dopants, such as organic dyes and rare earth metals, can be introduced in the reagent solutions end up uniformly dispersed in the final product. [109] [110]
The exchange or sharing of the electrons between two or more atoms is the main cause of chemical bonding. [17] In 1838, British natural philosopher Richard Laming first hypothesized the concept of an indivisible quantity of electric charge to explain the chemical properties of atoms. [3]
In the standard framework of particle interactions (part of a more general formulation known as perturbation theory), gluons are constantly exchanged between quarks through a virtual emission and absorption process. When a gluon is transferred between quarks, a color change occurs in both; for example, if a red quark emits a red–antigreen ...