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Elementary particle

Elementary particle
In particle physics, an elementary particle or fundamental particle is a particle whose substructure is unknown, thus it is unknown whether it is composed of other particles.[1] Known elementary particles include the fundamental fermions (quarks, leptons, antiquarks, and antileptons), which generally are "matter particles" and "antimatter particles", as well as the fundamental bosons (gauge bosons and Higgs boson), which generally are "force particles" that mediate interactions among fermions.[1] A particle containing two or more elementary particles is a composite particle. Everyday matter is composed of atoms, once presumed to be matter's elementary particles—atom meaning "indivisible" in Greek—although the atom's existence remained controversial until about 1910, as some leading physicists regarded molecules as mathematical illusions, and matter as ultimately composed of energy.[1][2] Soon, subatomic constituents of the atom were identified. Overview[edit] Main article: Standard Model Related:  Atomic structure

Atom The atom is a basic unit of matter that consists of a dense central nucleus surrounded by a cloud of negatively charged electrons. The atomic nucleus contains a mix of positively charged protons and electrically neutral neutrons (except in the case of hydrogen-1, which is the only stable nuclide with no neutrons). The electrons of an atom are bound to the nucleus by the electromagnetic force. Likewise, a group of atoms can remain bound to each other by chemical bonds based on the same force, forming a molecule. An atom containing an equal number of protons and electrons is electrically neutral, otherwise it is positively or negatively charged and is known as an ion. Chemical atoms, which in science now carry the simple name of "atom," are minuscule objects with diameters of a few tenths of a nanometer and tiny masses proportional to the volume implied by these dimensions. Etymology History of atomic theory Atomism First evidence-based theory The structure of atoms The physicist J. Structure

CSUCI-Olli courses Past &Present The Osher Lifelong Learning Institute courses span a wide range of topics from the arts, sciences, social sciences and more – in fact, all disciplines found in an excellent university. They are taught by university faculty and other professional experts. To enhance variety, no course is repeated within a two year span. Classes may have readings, but there are no tests, grades, or college credit, so readings are optional. To take advantage of classes, mature learners must be over the age of 50 and members of the Institute. Winter and Spring 2014 Courses Winter and Spring 2014 course descriptions (PDF, 58.2 KB) Updated 11/25/2013 Spring 2014 enrollment form (PDF, 98.6 KB) Updated 2/10/2014 Please call us at (805) 437-2748 to enroll in any of these courses! Taste of OLLI Courses Our Taste of OLLI Courses are our mini-courses provided on our Thousand Oaks Campus. Past OLLI Courses Fall 2013 course descriptions (PDF, 133.6 KB) Fall 2013 Enrollment Form (PDF, 90.0 KB) Classes Flyer (PDF, 808.7 KB)

Flavour (particle physics) In particle physics, flavour or flavor refers to a species of an elementary particle. The Standard Model counts six flavours of quarks and six flavours of leptons. They are conventionally parameterized with flavour quantum numbers that are assigned to all subatomic particles, including composite ones. For hadrons, these quantum numbers depend on the numbers of constituent quarks of each particular flavour. In atomic physics the principal quantum number of an electron specifies the electron shell in which it resides, which determines the energy level of the whole atom. In an analogous way, the five flavour quantum numbers of a quark specify which of six flavours (u, d, s, c, b, t) it has, and when these quarks are combined this results in different types of baryons and mesons with different masses, electric charges, and decay modes. If there are two or more particles which have identical interactions, then they may be interchanged without affecting the physics. Jump up ^ See table in S.

Atomic orbital The shapes of the first five atomic orbitals: 1s, 2s, 2px, 2py, and 2pz. The colors show the wave function phase. These are graphs of ψ(x, y, z) functions which depend on the coordinates of one electron. To see the elongated shape of ψ(x, y, z)2 functions that show probability density more directly, see the graphs of d-orbitals below. Each orbital in an atom is characterized by a unique set of values of the three quantum numbers n, ℓ, and m, which correspond to the electron's energy, angular momentum, and an angular momentum vector component, respectively. Atomic orbitals are the basic building blocks of the atomic orbital model (alternatively known as the electron cloud or wave mechanics model), a modern framework for visualizing the submicroscopic behavior of electrons in matter. Electron properties[edit] Wave-like properties: The electrons do not orbit the nucleus in the sense of a planet orbiting the sun, but instead exist as standing waves. Particle-like properties: History[edit]

List of particles This is a list of the different types of particles found or believed to exist in the whole of the universe. For individual lists of the different particles, see the individual pages given below. Elementary particles[edit] Fermions[edit] Fermions are one of the two fundamental classes of particles, the other being bosons. Fermions have half-integer spin; for all known elementary fermions this is 1⁄2. Quarks[edit] Leptons[edit] Bosons[edit] Bosons are one of the two fundamental classes of particles, the other being fermions. The fundamental forces of nature are mediated by gauge bosons, and mass is believed to be created by the Higgs Field. The graviton is added to the list[citation needed] although it is not predicted by the Standard Model, but by other theories in the framework of quantum field theory. Hypothetical particles[edit] Supersymmetric theories predict the existence of more particles, none of which have been confirmed experimentally as of 2014: Composite particles[edit] Hadrons[edit]

Atomic nucleus A model of the atomic nucleus showing it as a compact bundle of the two types of nucleons: protons (red) and neutrons (blue). In this diagram, protons and neutrons look like little balls stuck together, but an actual nucleus (as understood by modern nuclear physics) cannot be explained like this, but only by using quantum mechanics. In a nucleus which occupies a certain energy level (for example, the ground state), each nucleon has multiple locations at once. The nucleus is the very dense region consisting of protons and neutrons at the center of an atom. It was discovered in 1911 as a result of Ernest Rutherford's interpretation of the 1909 Geiger–Marsden gold foil experiment performed by Hans Geiger and Ernest Marsden under Rutherford's direction. The proton–neutron model of nucleus was proposed by Dmitry Ivanenko in 1932.[1] Almost all of the mass of an atom is located in the nucleus, with a very small contribution from the electron cloud. Introduction[edit] History[edit] Forces[edit]

Matthew C. Curtis Archaeology of Ethiopia and Eritrea Ceramic market, Yeha, Ethiopia, July 2008 Photo © M.C. Curtis Matt's Publications and Reports Curtis, M. C. 2013. Curtis, M. Curtis, M. Arthur, K. Curtis, M. Arthur, K. Curtis, M. Arthur, J. Schmidt, P. Curtis, M. Curtis, M. Curtis, M. Curtis, M. Schmidt, P. Schmidt, P. Wenig, S. and M. Schmidt, P. D’Andrea, A. Schmidt, P. Curtis, M. Curtis, M. Curtis, M. Curtis, M. Curtis, M. Schmidt, P. Curtis, M. Schmidt, P. Schmidt, P. Walz, J. Walz, J. Curtis, M. Curtis, M. Curtis, M. Curtis, M.

Fundamental interaction Fundamental interactions, also called fundamental forces or interactive forces, are modeled in fundamental physics as patterns of relations in physical systems, evolving over time, that appear not reducible to relations among entities more basic. Four fundamental interactions are conventionally recognized: gravitational, electromagnetic, strong nuclear, and weak nuclear. Everyday phenomena of human experience are mediated via gravitation and electromagnetism. The strong interaction, synthesizing chemical elements via nuclear fusion within stars, holds together the atom's nucleus, and is released during an atomic bomb's detonation. The weak interaction is involved in radioactive decay. (Speculations of a fifth force—perhaps an added gravitational effect—remain widely disputed.) In modern physics, gravitation is the only fundamental interaction still modeled as classical/continuous (versus quantum/discrete). Overview of the fundamental Interaction[edit] The interactions[edit]

Neutron The neutron is a subatomic hadron particle that has the symbol n or n0. Neutrons have no net electric charge and a mass slightly larger than that of a proton. With the exception of hydrogen-1, the nucleus of every atom consists of at least one or more of both protons and neutrons. Protons and neutrons are collectively referred to as "nucleons". While the bound neutrons in nuclei can be stable (depending on the nuclide), free neutrons are unstable; they undergo beta decay with a mean lifetime of just under 15 minutes (881.5±1.5 s).[5] Free neutrons are produced in nuclear fission and fusion. The neutron has been key to the production of nuclear power. Discovery[edit] In 1920, Ernest Rutherford conceived the possible existence of the neutron.[2][7] In particular, Rutherford considered that the disparity found between the atomic number of an atom and its atomic mass could be explained by the existence of a neutrally charged particle within the atomic nucleus. Intrinsic properties[edit]

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