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This Review contains major "Nucleus"- related terms, short phrases and links grouped together in the form of Encyclopedia article.
- A nucleus is a bound state of protons and neutrons (nucleons).
- A nucleus is a collection of a large number of up and down quarks, confined into triplets (neutrons and protons).
- A nucleus is a collection of protons and neutrons, in the same way that a wall is a collection of bricks.
- A nucleus is a dense clustering of stars at the very center of a galaxy.
- A nucleus is most stable when all of its nucleons occupy the lowest possible states without violating this occupancy rule.
- As the number of protons increases, an increasing ratio of neutrons are needed to form a stable nucleus (see graph at right).
- Thus, the final, stable nucleus was one unit higher in mass number and one unit higher in atomic number than the initial target nucleus.
- Hence the energy required to separate an electron from the atom varies inversely with its distance from the nucleus.
- The total energy required to break up a nucleus into its constituent protons and neutrons can be calculated from, called nuclear binding energy.
- At the atomic level binding energy is derived from Electromagnetic interaction and is the energy required to assemble an atom from electrons and a nucleus.
- Nuclear binding energy can be computed from the difference in mass of a nucleus and the sum of the mass of the neutrons and protons that make up the nucleus.
- The amount of energy required to break the nucleus of an atom into its isolated nucleons is called nuclear binding energy.
- Nuclear binding energy is derived from the strong nuclear force and is the energy required to disassemble a nucleus into free unbound neutrons and protons.
- Nuclear fission is the process of splitting a nucleus into roughly equal parts, and releasing energy and neutrons in the process.
- Nuclear fission is the opposite process, causing the nucleus to emit some amount of nucleons—usually through radioactive decay.
- The number of protons and neutrons in the atomic nucleus may also change, via nuclear fusion, nuclear fission or radioactive decay.
- Other ways a nucleus can become unstable is for one or more extra nucleons to be introduced into the nucleus, creating an unstable nucleus.
- It is an unstable nucleus, but everything is stuck together (with binding energy or nuclear glue) until the instability "wins" and the nucleus decays.
- An unstable nucleus spontaneously emits particles and energy in a process known as radioactive decay.
- At the same time, the nucleus emits very quickly a number of fast neutrons, the same type of particle that initiated the fission of the uranium nucleus.
- Hahn and Strassmann, two german scientists, demonstrate that the uranium nucleus can be cut in two parts: this is the fission of the nucleus.
- Also, once a uranium nucleus is split, multiple neutrons are released which are used to split other uranium nuclei.
- Gamma rays consist of high energy photons with energies above about 100 keV. Nuclear physics is the branch of physics concerned with the nucleus of the atom.
- Nuclear physics is the branch of physics concerned with the nucleus of the atom.
- Similar, but not identical, arguments can be applied to the protons and neutrons in the atomic nucleus: see the shell model of nuclear physics.
- After the nucleus of the atom was discovered in 1911 by Ernest Rutherford, the nucleus of ordinary hydrogen was recognized to be a single proton.
- Ernest Rutherford suggested that the nucleus of an atom was a small, highly condensed and positively charged structure.
- This model was later proved incorrect when Ernest Rutherford showed that the positive charge is concentrated in the nucleus of the atom.
- Following the discovery of the nucleus in 1911, a model was developed in which each atom is made up of electrons surrounding a central nucleus.
- The atom is a basic unit of matter that consists of a dense, central nucleus surrounded by a cloud of negatively charged electrons.
- The model of an atom whose electrons are pictured as describing "Keplerian" orbits about the central nucleus.
- Alpha particle: (Image) the nucleus of a helium atom, made up of two neutrons and two protons with a charge of +2.
- In hydrogen atom and helium atom, the buoyant force is the only force that keeps the electron (electrons in helium) from falling into the nucleus.
- Alpha particles have the same nucleus as the helium atom but lack the two electrons that make helium stable.
- Earlier, I was telling Alex about the mass defect: the mass of any nucleus is less than the sum of the separate masses of its protons and neutrons.
- Mass Defect The difference in the mass of a nucleus and the sum of the masses of its constituent particles.
- When the nucleons are grouped together to form a nucleus, they lose a small amount of mass, i.e., there is mass defect.
- Fission: The splitting of a heavy nucleus into two, accompanied by the release of a relatively large amount of energy and usually one or more neutrons.
- The modern understanding of the atom is that it consists of a heavy nucleus of positive charge surrounded by a cloud of light, negatively charged electrons.
- Fission occurs because of the electrostatic repulsion created by the large number of positively charged protons contained in a heavy nucleus.
- In physics, nuclear fission is a process where a large nucleus such as uranium is split into two smaller nuclei.
- Spontaneous Fission: In this process, the nucleus disintegrates into two or more smaller nuclei and other particles.
- When a nucleus splits, there are several decay products including radiation, neutrons, and two new smaller nuclei (usually referred to as fission products).
- Some organelles, such as mitochondria and chloroplasts, have their own genetic material separate from that found in the nucleus of the cell.
- These areas include the nucleus, numerous mitochondria and other organelles such as the golgi body, and or chloroplasts within each of their cells.
- Prokaryotes do not have a nucleus, mitochondria or any other membrane bound organelles.
- Structurally, the nucleus is composed of three main parts, the nucleolus, the nuclear envelope, and the chromatin.
- It contains a number of proteins involved in the structural organization of the nucleus and the attachment of chromatin to the nuclear envelope.
- Especially intensively stained are the structures that are found in the nucleus, such as chromatin granules, nucleolus and nuclear envelope.
- For example, it requires only 13.6 eV to strip a ground-state electron from a hydrogen atom, compared to 2.23 million eV for splitting a deuterium nucleus.
- To summarize, the deuterium nucleus is antisymmetric in terms of isospin, and has spin 1 and even (+1) parity.
- Tritium is also produced in heavy water-moderated reactors whenever a deuterium nucleus captures a neutron.
- The deuterium nucleus is twice as heavy as the hydrogen nucleus because it contains a neutron as well as a proton.
- This diagram illustrates a nuclear fusion process that forms a deuterium nucleus, consisting of a proton and a neutron, from two protons.
- The deuterium nucleus, or deuteron (one proton plus one neutron), makes an excellent bombarding particle for inducing nuclear reactions.
- Almost all of the mass in an atom is made up from the protons and neutrons in the nucleus, with a very small contribution from the orbiting electrons.
- In normal circumstances the number of orbiting electrons equals the number of protons in the nucleus, and the atom as a whole is electrically neutral.
- The Spin on Spintronics An atom includes a nucleus of protons and neutrons, and a shell of orbiting electrons.
- Just like Rutherford's model, Bohr's atom had a positively charged nucleus surrounded by electrons … with some slight modifications.
- Now, Rutherford's atom, which has electrons orbiting the nucleus, definitely has accelerated charges (i.e., the orbiting electrons).
- Protons had been identified in 1902, and Rutherford had proposed in 1914 that they must form part of the nucleus.
- In a neutral atom, the number of electrons orbiting the nucleus equals the number of protons in the nucleus.
- Helium-4 is made up of six fermi particles: two electrons orbiting a nucleus made up of two protons and two neutrons.
- The arrangement of an atoms's energy orbits depends on the number of protons and neutrons in the nucleus and the number of electrons orbiting the nucleus.
- Just as electrons orbit around the nucleus of an atom, neutrons and protons move around in orbits within the nucleus itself.
- Protons and neutrons cluster together to form the nucleus (central mass) of the atom while the electrons orbit the nucleus much like planets around a sun.
- The protons are grouped at the center of the atom in the nucleus, while the electrons orbit around the nucleus of the atom.
- These parts include the hypothalamus, nucleus of the solitary tract, reticular formation, amygdala, hippocampus, and olfactory cortex.
- The amygdala is a nucleus known to contribute a great deal to the emotion of fear.
- Structures contained in the basal ganglia include the amygdala, globus pallidus, and striatum (containing the caudate nucleus and the putamen).
- At that moment, the fMRI scan showed, the neurons in a reflexive, or emotional, part of my brain called the nucleus accumbens fired like wild.
- Nucleus accumbens can be found at the point where the internal capsule does not comppleteley separate the caudate from putamen.
- The nucleus accumbens is a nucleus just below the previous nuclei.
- The lentiform nucleus or lenticular nucleus comprises the putamen and the globus pallidus within the basal ganglia.
- In reality, the caudate and the putamen are all one nucleus, which was coincidentally cut in half by the internal capsule.
- Putamen. The putamen is also part of the basal ganglia, being one of the components (with the globus pallidus) of the lenticular nucleus.
- Components of the subthalamus include the SUBTHALAMIC NUCLEUS, zona incerta, nucleus of field H, and the nucleus of ansa lenticularis.
- The basal ganglia (BG) are deep brain nuclei that include the striatum, the globus pallidus, the subthalamic nucleus, and the substantia nigra.
- The other parts of the basal ganglia include the dorsal striatum, substantia nigra, nucleus accumbens, and the subthalamic nucleus.
- In physics, nuclear fusion (a thermonuclear reaction) is a process in which two nuclei join to form a larger nucleus, thereby giving off energy.
- The sun is powered by nuclear fusion, in which two nuclei collide and merge to form a larger nucleus.
- Protons and neutrons are most important and best known for constituting atomic nuclei, but they can also be found on their own, not part of a larger nucleus.
- At the nuclear level, binding energy is derived from the strong nuclear force and is the energy required to disassemble a nucleus into neutrons and protons.
- The second order effect for the Strong Nuclear Force is to hold protons and neutrons together in the nucleus of an atom.
- The strong nuclear force is responsible for the cohesion of the quarks inside a proton or a neutron and of the protons and neutrons inside an atomic nucleus.
- When a nucleus emits an α or β particle, the daughter nucleus is sometimes left in an excited state.
- The daughter nucleus will have two less protons and two less neutrons than the parent nucleus.
- Most radionuclides after an alpha decay or a beta decay leave the daughter nucleus in an excited state.
- If one of the neutrons could beta decay it would produce a Lithium 4 nucleus (3 protons and one neutron) plus an electron and an anti-electron type neutrino.
- A nucleus with an excess of neutrons is radioactive; the extra neutrons convert to protons by beta decay (see radioactivity).
- Each of the two types of beta decay acts to move a nucleus toward a ratio of neutrons and protons which has the least energy for the combination.
- In a neutral atom the number of electrons is identical to the number of positive charges on the nucleus.
- The positive charges on the protons are balanced by a number of negatively-charged electrons in motion around the nucleus.
- The energy depended on the atomic number for that element, and the atomic number corresponded to the number of positive charges in the nucleus.
- The nucleus of an atom is the very small dense region, of positive charge, in its centre consisting of nucleons (protons and neutrons).
- Electrons have a negative charge, and the protons that make up the nucleus of an atom have a positive charge.
- Its main job is to hold together the subatomic particles of the nucleus (protons, which carry a positive charge, and neutrons, which carry no charge.
- The nucleus of the most common isotope of the hydrogen atom is a single proton (it contains no neutrons).
- When two deuterium nuclei fuse, they momentarily form the nucleus of the common isotope of helium, called helium-4.
- This tightly bound quartet emerges during radioactive decay of nuclei like uranium-238, and is itself the nucleus of the common isotope of helium.
- The nucleus of most atoms (all except the most common isotope of hydrogen, protium, which consists of a single proton only) consists of protons and neutrons.
- Except for the nucleus of ordinary (light) hydrogen, which has a single proton, all atomic nuclei contain both protons and neutrons.
- The nucleus of a hydrogen atom consists of a single proton, and the nucleus of any other atom contains protons and neutrons, collectively called nucleons.
- Also, particles that interact by means of the strong force, the force that holds parts of the nucleus together, are explained in terms of quarks.
- A force called the strong force opposes and overcomes the force of repulsion between the protons and holds the nucleus together.
- The strong force between baryons in the nucleus is called the residual strong force.
- When a nucleon (proton or neutron) is added to a nucleus, it is attracted by the strong force to other nucleons, but only to those in direct contact.
- A nucleon at the surface of a nucleus interacts with fewer other nucleons that one in the interior of the nucleus and hence its binding energy is less.
- Reason for Variation of Binding Energy The binding energy of a nucleon is due to its (nuclear) interaction with the immediate neighbours in the nucleus.
- In the alpha decay of a nucleus, the change in binding energy appears as the kinetic energy of the alpha particle and the daughter nucleus.
- Alpha decay is a radioactive process in which a particle with two neutrons and two protons is ejected from the nucleus of a radioactive atom.
- Alpha decay can most simply be described like this: 1) The nucleus of an atom splits into two parts.
- In alpha decay the radioactive element decays by emitting a helium nucleus (2 protons and 2 neutrons), giving another element, plus helium-4.
- This, then, represents the "binding energy" of the protons and neutrons in the helium nucleus.
- An alpha particle is identical to a helium nucleus, and both mass number and atomic number are the same.
- In some atoms the binding energy is not strong enough to hold the nucleus together, and the nuclei of these atoms are said to be unstable.
- All nuclei contain protons and neutrons, except the nucleus of normal hydrogen (atomic mass of one), which consists of a single proton.
- Nuclei readily capture neutrons, which, unlike protons or alpha particles, are not repelled from the nucleus by a positive charge.
- It is made of a nucleus surrounded by cytoplasm, organelles (similar to organs in a body) and proteins.
- Some proteins that are made in the cytoplasm contain structural features that target them for transport into mitochondria or the nucleus.
- The nucleus is spheroid in shape and separated from the cytoplasm by a double membrane called the nuclear envelope.
- Tritium is occasionally a direct product of nuclear fission In physics, fission is a nuclear process, meaning it occurs in the nucleus of an atom.
- Fission (fissioning): the splitting of a nucleus into at least two other nuclei that releases a large amount of energy.
- Fission of uranium or thorium, on the other hand, is much easier because neutrons are used to induce destabilization and splitting of the nucleus.
- Radioactive decay refers to processes where the nucleus of an isotope emits particles such as electrons and photons (gamma rays).
- Depending on the number of protons and neutrons, the nucleus may be unstable and subject to radioactive decay.
- Nuclear fission is the opposite process, causing a nucleus to split into two smaller nuclei - usually through radioactive decay.
- On the way to V1, these fibers enter a nucleus in the center of the brain called the thalamus.
- The medial geniculate nucleus is a nucleus of the thalamus that acts as a relay for auditory information.
- MESENCEPHALON + BASAL GANGLIA: Also supplies posterior limb of internal capsule, and parts of the Thalamus and Lentiform Nucleus.
- Includes caudate nucleus, globus pallidus, and putamen; thalamus, subthalamus, substantia nigra, and red nucleus sometimes included.
- The basal ganglia consists of the caudate nucleus and the lenticular nucleus, the latter consisting of the putamen and the globus pallidus.
- She draws a diagram of how the basal ganglia is related to the caudate nucleus, the lentiform nucleus, the putemen, the globus pallidus, and the subthalamus.
- An atom consists of an extremely small, positively charged nucleus surrounded by a cloud of negatively charged electrons.
- An atom is a complex arrangement of negatively charged electrons arranged in defined shells about a positively charged nucleus.
- An atom consists of a number of negatively charged electrons, orbiting around a positively charged nucleus.
- It causes positively charged protons to attract negatively charged electrons and holds them in orbit around the nucleus of the atom.
- At the center of the atom is a tiny, positively charged nucleus composed of protons and neutrons (known as nucleons).
- Rutherford had shown that the atom consisted of a positively charged nucleus, with negatively charged electrons in orbit around it.
- A deuteron (the nucleus of a deuterium atom, with no electron) consists of one proton and one neutron.
- The nucleus of deuterium, called a deuteron, contains one proton and one neutron, whereas the far more common hydrogen nucleus contains no neutron.
- The nucleus of the atom of heavy hydrogen, or deuterium, is called a deuteron.
- Nature > Matter > Atoms > Atom
- Nature > Matter > Particles > Electrons
- Encyclopedia of Keywords > Nature > Matter > Particles
- Encyclopedia of Finance. > Technology > Energy
- Encyclopedia of Keywords > Nature > Matter > Mass
* Alpha Particle
* Atomic Nucleus
* Atomic Number
* Binding Energy
* Cell Nucleus
* Hydrogen Atom
* Hydrogen Nucleus
* Mass Number
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