atomic nucleus
Quick Summary
The atomic nucleus is the positively charged center of an atom, containing almost all of its mass. It is composed of protons, which carry a positive charge, and neutrons, which have no charge. Protons and neutrons are collectively known as nucleons.1234
The nucleus is incredibly small compared to the overall size of the atom, with its volume occupying only a tiny fraction of the atom's space. Despite its size, the nucleus is held together by the strong nuclear force, which overcomes the electrical repulsion between the positively charged protons. The number of protons in a nucleus determines the chemical element, while the number of neutrons can vary, creating isotopes of that element. The nucleus is also the site of nuclear reactions, such as fission and fusion, which release immense amounts of energy.12356
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- spectroscopyPerturbations of levels
…the finite mass of the nucleus. For heavier atoms, the main contribution comes from the fact that the volume of the nucleus increases as the number of neutrons increases. The nucleus may behave as a small magnet because of internal circulating currents; the magnetic fields produced in this way may…
Read More…the finite mass of the nucleus. For heavier atoms, the main contribution comes from the fact that the volume of the nucleus increases as the number of neutrons increases. The nucleus may behave as a small magnet because of internal circulating currents; the magnetic fields produced in this way may…
Read More - isotopePhysical properties associated with isotopes
…the interplay, distinctive for each nucleus, of nuclear and electrostatic forces between neutrons, protons, and electrons. Helium-6, for example, is radioactive, whereas helium-4 is stable. Second, the spatial distribution of the protons in the nucleus affects in measurable ways the behaviour of the surrounding electrons. The addition of one neutron…
Read More…the interplay, distinctive for each nucleus, of nuclear and electrostatic forces between neutrons, protons, and electrons. Helium-6, for example, is radioactive, whereas helium-4 is stable. Second, the spatial distribution of the protons in the nucleus affects in measurable ways the behaviour of the surrounding electrons. The addition of one neutron…
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atomNuclear energy…can be derived from the atomic nucleus. The basic physical principle behind this fact is that the total mass present after a nuclear reaction is less than before the reaction. This difference in mass, via the equation E = mc2, is converted into what is called nuclear energy.
Read More…can be derived from the atomic nucleus. The basic physical principle behind this fact is that the total mass present after a nuclear reaction is less than before the reaction. This difference in mass, via the equation E = mc2, is converted into what is called nuclear energy.
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subatomic particle…the small but very dense nucleus of the atom, the positively charged protons and the electrically neutral neutrons. But these basic atomic components are by no means the only known subatomic particles. Protons and neutrons, for instance, are themselves made up of elementary particles called quarks, and the electron is
Read More…the small but very dense nucleus of the atom, the positively charged protons and the electrically neutral neutrons. But these basic atomic components are by no means the only known subatomic particles. Protons and neutrons, for instance, are themselves made up of elementary particles called quarks, and the electron is
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- atomThe nucleus
The primary constituents of the nucleus are the proton and the neutron, which have approximately equal mass and are much more massive than the electron. For reference, the accepted mass of the proton is 1.672621777 × 10−24 gram, while that of the…
Read MoreThe primary constituents of the nucleus are the proton and the neutron, which have approximately equal mass and are much more massive than the electron. For reference, the accepted mass of the proton is 1.672621777 × 10−24 gram, while that of the…
Read More - spectroscopyBasic atomic structure
…charged electrons bound to a nucleus containing an equal number of positively charged protons. The nucleus contains a certain number (Z) of protons and a generally different number (N) of neutrons. The diameter of a nucleus depends on the number of protons and neutrons and is typically 10−14 to 10−15
Read More…charged electrons bound to a nucleus containing an equal number of positively charged protons. The nucleus contains a certain number (Z) of protons and a generally different number (N) of neutrons. The diameter of a nucleus depends on the number of protons and neutrons and is typically 10−14 to 10−15
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chemical elementThe structure of atoms…within an atom, a small nucleus, which generally contains both protons and neutrons, is surrounded by a swarm, or cloud, of electrons. The fundamental properties of these subatomic particles are their weight and electrical charge. Whereas protons carry a positive charge and electrons a negative one, neutrons are electrically neutral.…
Read More…within an atom, a small nucleus, which generally contains both protons and neutrons, is surrounded by a swarm, or cloud, of electrons. The fundamental properties of these subatomic particles are their weight and electrical charge. Whereas protons carry a positive charge and electrons a negative one, neutrons are electrically neutral.…
Read More- magic number
The magic numbers for nuclei are 2, 8, 20, 28, 50, 82, and 126. Thus, tin (atomic number 50), with 50 protons in its nucleus, has 10 stable isotopes, whereas indium (atomic number 49) and antimony (atomic number 51) have only 2 stable isotopes apiece. The doubly magic alpha…
Read MoreThe magic numbers for nuclei are 2, 8, 20, 28, 50, 82, and 126. Thus, tin (atomic number 50), with 50 protons in its nucleus, has 10 stable isotopes, whereas indium (atomic number 49) and antimony (atomic number 51) have only 2 stable isotopes apiece. The doubly magic alpha…
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- spectroscopyRadio-frequency spectroscopy
the electrons and the nucleus and by the mutual repulsion of the electrons. Electrons and nuclei have magnetic properties in addition to these electrostatic properties. The spin-orbit interaction has been discussed above (see Fine and hyperfine structure of spectra). Other, usually weaker, magnetic interactions within the atom exist between…
Read Morethe electrons and the nucleus and by the mutual repulsion of the electrons. Electrons and nuclei have magnetic properties in addition to these electrostatic properties. The spin-orbit interaction has been discussed above (see Fine and hyperfine structure of spectra). Other, usually weaker, magnetic interactions within the atom exist between…
Read More - excitation
…to a system—such as an atomic nucleus, an atom, or a molecule—that results in its alteration, ordinarily from the condition of lowest energy (ground state) to one of higher energy (excited state).
Read More…to a system—such as an atomic nucleus, an atom, or a molecule—that results in its alteration, ordinarily from the condition of lowest energy (ground state) to one of higher energy (excited state).
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- spin
…with a subatomic particle or nucleus and measured in multiples of a unit called the Dirac h, or h-bar (ℏ), equal to the Planck constant divided by 2π. For electrons, neutrons, and protons, the multiple is 0.5; pions have zero spin. The total angular momentum of nuclei more complex than…
Read More…with a subatomic particle or nucleus and measured in multiples of a unit called the Dirac h, or h-bar (ℏ), equal to the Planck constant divided by 2π. For electrons, neutrons, and protons, the multiple is 0.5; pions have zero spin. The total angular momentum of nuclei more complex than…
Read More - quantum mechanicsCesium clock
Like electrons, many atomic nuclei have spin. The spin of these nuclei produces a set of small effects in the spectra, known as hyperfine structure. (The effects are small because, though the angular momentum of a spinning nucleus is of the same magnitude as that of an electron,…
Read MoreLike electrons, many atomic nuclei have spin. The spin of these nuclei produces a set of small effects in the spectra, known as hyperfine structure. (The effects are small because, though the angular momentum of a spinning nucleus is of the same magnitude as that of an electron,…
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chemical analysisNuclear magnetic resonance…sufficient to cause a spinning nucleus in some atoms to move to a different spin state in the presence of a magnetic field. Consequently, nuclear magnetic resonance spectrometry is useful for examining atomic nuclei and the transitions between their possible spin states. Because nuclei from different atoms have different possible…
Read More…sufficient to cause a spinning nucleus in some atoms to move to a different spin state in the presence of a magnetic field. Consequently, nuclear magnetic resonance spectrometry is useful for examining atomic nuclei and the transitions between their possible spin states. Because nuclei from different atoms have different possible…
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magnetic resonanceNuclear magnetic resonance…increased by the interaction between nuclear spins. As already mentioned in connection with motion narrowing in liquids, the usual magnetic dipolar interactions are averaged out by molecular motion and do not split the NMR spectra. There exists, however, an indirect interaction between nuclear spins, caused by the electrons, that splits…
Read More…increased by the interaction between nuclear spins. As already mentioned in connection with motion narrowing in liquids, the usual magnetic dipolar interactions are averaged out by molecular motion and do not split the NMR spectra. There exists, however, an indirect interaction between nuclear spins, caused by the electrons, that splits…
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- Aage N. Bohr
…the asymmetrical shapes of certain atomic nuclei.
Read More…the asymmetrical shapes of certain atomic nuclei.
Read More - Ben Roy Mottelson
…distort the shape of the nucleus, thus challenging the widely accepted theory that all nuclei are perfectly spherical. Subsequently it was discovered that such asymmetries occur in atoms of all elements.
Read More…distort the shape of the nucleus, thus challenging the widely accepted theory that all nuclei are perfectly spherical. Subsequently it was discovered that such asymmetries occur in atoms of all elements.
Read More - James Rainwater
…the asymmetrical shapes of certain atomic nuclei.
Read More…the asymmetrical shapes of certain atomic nuclei.
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Rutherford model…positively charged core called a nucleus, in which nearly all the mass is concentrated, around which the light, negative constituents, called electrons, circulate at some distance, much like planets revolving around the Sun.
Read More…positively charged core called a nucleus, in which nearly all the mass is concentrated, around which the light, negative constituents, called electrons, circulate at some distance, much like planets revolving around the Sun.
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principles of physical scienceDevelopment of the atomic theory…determined that a small, massive nucleus carries all the positive charge whose magnitude, expressed as a multiple of the fundamental charge of the proton, is the atomic number. An equal number of electrons carrying a negative charge numerically equal to that of the proton form a cloud whose diameter is…
Read More…determined that a small, massive nucleus carries all the positive charge whose magnitude, expressed as a multiple of the fundamental charge of the proton, is the atomic number. An equal number of electrons carrying a negative charge numerically equal to that of the proton form a cloud whose diameter is…
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Ernest RutherfordUniversity of Cambridge… is the same as the nucleus of an ordinary helium atom—consisting of two protons and two neutrons—and the beta particle is the same as an electron or its positive version, a positron.) For the next several years these radiations were of primary interest; later the
Read More… is the same as the nucleus of an ordinary helium atom—consisting of two protons and two neutrons—and the beta particle is the same as an electron or its positive version, a positron.) For the next several years these radiations were of primary interest; later the
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