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Quantum mechanics is a fundamental theory that describes the behavior of nature at and below the scale of atoms. [2]: 1.1 It is the foundation of all quantum physics, which includes quantum chemistry, quantum field theory, quantum technology, and quantum information science. Quantum mechanics can describe many systems that classical physics cannot.
A synthetic element is one of 24 known chemical elements that do not occur naturally on Earth: they have been created by human manipulation of fundamental particles in a nuclear reactor, a particle accelerator, or the explosion of an atomic bomb; thus, they are called "synthetic", "artificial", or "man-made".
The word quantum is the neuter singular of the Latin interrogative adjective quantus, meaning "how much"."Quanta", the neuter plural, short for "quanta of electricity" (electrons), was used in a 1902 article on the photoelectric effect by Philipp Lenard, who credited Hermann von Helmholtz for using the word in the area of electricity.
Leptonic atoms, named using -onium, are exotic atoms constituted by the bound state of a lepton and an antilepton. Examples of such atoms include positronium (e − e +), muonium (e − μ +), and "true muonium" (μ − μ +). Of these positronium and muonium have been experimentally observed, while "true muonium" remains only theoretical.
Due to the nature of electrons to obey the Pauli exclusion principle, in which no two electrons may be found in the same quantum state, bound electrons pair up with each other, with one member of each pair in a spin up state and the other in the opposite, spin down state. Thus these spins cancel each other out, reducing the total magnetic ...
Applications of quantum mechanics include explaining phenomena found in nature as well as developing technologies that rely upon quantum effects, like integrated circuits and lasers. [note 1] Quantum mechanics is also critically important for understanding how individual atoms are joined by covalent bonds to form molecules.
In the words of quantum physicist Richard Feynman, quantum mechanics deals with "nature as She is—absurd". [4] Features of quantum mechanics often defy simple explanations in everyday language. One example of this is the uncertainty principle : precise measurements of position cannot be combined with precise measurements of velocity.
Quantum tunneling is a direct consequence of this wave-like nature of quantum entities that permits the passing-through of a potential energy barrier that would otherwise restrict the entity. [91] Moreover, it depends on the shape and size of a potential barrier relative to the incoming energy of a particle. [92]