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Topic: Bohr model

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Niels Bohr

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	The Bohr Model
		The Bohr Model is probably familar as the "planetary model" of the atom illustrated in the adjacent figure that, for example, is used as a symbol for atomic energy (a bit of a misnomer, since the energy in "atomic energy" is actually the energy of the nucleus, rather than the entire atom).
		In the Bohr Model the neutrons and protons (symbolized by red and blue balls in the adjacent image) occupy a dense central region called the nucleus, and the electrons orbit the nucleus much like planets orbiting the Sun (but the orbits are not confined to a plane as is approximately true in the Solar System).
		This similarity between a planetary model and the Bohr Model of the atom ultimately arises because the attractive gravitational force in a solar system and the attractive Coulomb (electrical) force between the positively charged nucleus and the negatively charged electrons in an atom are mathematically of the same form.
	csep10.phys.utk.edu /astr162/lect/light/bohr.html (0 words)

	O=CHemBohrModel
		The model bears his name because of his interpretation of the emission spectrum of hydrogen: If a small amount of hydrogen gas is confined within a glass tube and subjected to a high voltage, it emits light, some of which falls in the visible region of the electromagnetic spectrum.
		Bohr knew that the emission of light was the way the atoms released the energy they had absorbed when the high voltage was applied.
		Bohr's success in rationalizing the emission spectrum of hydrogen led to the general acceptance of the planetary model of the atom.
	www.usm.maine.edu /~newton/Chy251_253/Lectures/BohrModel/BohrModel.html (365 words)

	Bohr atom
		In the incorrect model of the atom, proposed by J. Thomson in 1904 (sometimes called the plum-pudding model), electrons were supposed to be embedded in a "sphere of positive electrification", and the mass of the atom was supposed to be contained in the electrons.
		In Bohr's model of the hydrogen atom the electron is allowed certain orbits around the nucleus: in jumping from one orbit to an inner one, the atom emits light of a certain frequency which depends on the orbits concerned.
		A model of the atom, first described by Niels Bohr, that explains the emission and absorption of radiation as transitions between stationary electronic states in which the electron orbits the nucleus at a definite distance.
	www.daviddarling.info /encyclopedia/B/Bohr_atom.html (745 words)

	A Science Odyssey: People and Discoveries: Rutherford and Bohr describe atomic structure
		Bohr soon went to visit Ernest Rutherford (a former student of Thomson's) in another part of England, where Rutherford had made a brand-new discovery about the atom.
		Bohr suggested the revolutionary idea that electrons "jump" between energy levels (orbits) in a quantum fashion, that is, without ever existing in an in-between state.
		Bohr's theory that electrons existed in set orbits around the nucleus was the key to the periodic repetition of properties of the elements.
	www.pbs.org /wgbh/aso/databank/entries/dp13at.html (702 words)

	Bohr Model: World of Earth Science
		Before Bohr, the classical model of the atom was similar to the Copernican model of the solar system where, just as planets orbit the Sun, electrically negative electrons moved in orbits about a relatively massive, positively charged nucleus.
		According to the Bohr model, when an electron is excited by energy it jumps from its ground state to an excited state (i.e., a higher energy orbital).
		Regardless, Bohr's model remains fundamental to the study of chemistry, especially the valence shell concept used to predict an element's reactive properties.
	science.enotes.com /earth-science/bohr-model (1025 words)

	Niels Bohr
		Bohr was among the first to see the importance of the atomic number, which indicates the position of an element in the periodic table and is equal to the number of natural units of electric charge on the nuclei of its atoms.
		Bohr returned to Copenhagen from Manchester during the summer of 1912, married Margrethe Nørlund, and continued to develop his new approach to the physics of the atom.
		Einstein greatly admired Bohr's early work, referring to it as "the highest form of musicality in the sphere of thought," but he never accepted Bohr's claim that quantum mechanics was the "rational generalization of classical physics" demanded for the understanding of atomic phenomena.
	www.crystalinks.com /bohr.html (2000 words)

	Bohr Model of the Atom
		While the Bohr Model of the atom is primarily of historical interest to the working physicist, it displays the essential qualities of the atom as intuitively as possible.
		We start with a model of the atom which looks like a solar system: in place of the sun we have the positively charged nucleus, and instead of planets we have negatively charged electrons (see the next chapter).
		But Bohr's model leads to a decent agreement with experimental data (see Section C) and, as we shall see at the end of Chapter 9, it provides us with some clues to the nature of the electron itself.
	www.rwc.uc.edu /koehler/biophys/6a.html (714 words)

	Bohr model Summary (Site not responding. Last check: )
		Bohr's model of the atom was important because it introduced quantized energy states for the electrons.
		Introduced by Niels Bohr in 1913, the model's key success was in explaining the Rydberg formula for the spectral emission lines of atomic hydrogen; while the Rydberg formula had been known experimentally, it did not gain a theoretical underpinning until the Bohr model was introduced.
		The Bohr model is sometimes known as the semiclassical model of the atom, as it adds some primitive quantization conditions to what is otherwise a classical mechanics treatment.
	www.bookrags.com /Bohr_model (4442 words)

	Atomic Theory II
		Bohr knew that when pure elements were excited by heat or electricity, they gave off distinct colors rather than white light.
		Because the emitted light was due to the movement of electrons, Bohr suggested that electrons could not move continuously in the atom (as Rutherford had suggested) but only in precise steps.
		Key to Bohr's theory was the fact that the electron could only "jump" and "fall" to precise energy levels, thus emitting a limited spectrum of light.
	www.visionlearning.com /library/module_viewer.php?mid=51 (1036 words)

	Emission Spectrum of Hydrogen
		Bohr then used classical physics to show that the energy of an electron in any one of these orbits is inversely proportional to the square of the integer n.
		Thus, once he introduced his basic assumptions, Bohr was able to derive an equation that matched the relationship obtained from the analysis of the spectrum of the hydrogen atom.
		We still talk about the Bohr model of the atom even if the only thing this model can do is explain the spectrum of the hydrogen atom because it was the last model of the atom for which a simple physical picture can be constructed.
	chemed.chem.purdue.edu /genchem/topicreview/bp/ch6/bohr.html (1995 words)

	Bohr's Atomic Model
		Bohr said that the electron had to release energy to change its energy so the differences between the energies of light seen in the atomic spectrum should correspond to the differences in energies of the energy levels.
		Bohr proposed that each orbit was defined by a certain energy so he said that the electron was in an energy level.
		Bohr's definition of an orbital turned out to be too defined: the quantum mechanical versions of an orbital in much different: but the idea that only certain orbitals exist still holds true in the quantum mechanical model.
	students.ed.uiuc.edu /swires/CAP/bohr.htm (629 words)

	Bohr Model
		The Bohr model of the atom,developed in 1913, was an attempt by Neils Bohr to come to an accommodation with two opposing schools of thought on the nature of particulate matter.
		The model did accurately predict the parameters of a one electron system like the Hydrogen atom, but with multi-electron atomic systems the predicted parameters were not forthcoming.
		The model is still used as a way of keeping up with the number of electrons in the various shells or orbits.
	members.aol.com /profchm/bohr.html (0 words)

	Niels Bohr Biography
		Bohr published a theory in 1913 on the structure of the atom based on one of Ernest Rutherford's theories.
		Later in 1916 Bohr became a professor of physics at the University of Copenhagen.
		In 1920 Niels Bohr was named director of the new Institute of Theoretical Physics at the University of Copenhagen.
	library.thinkquest.org /28582/bio/bohr.htm (298 words)

	Bohr's atom model
		Niels Bohr to a new theory describing the laws governing the atom.
		Having this formula one can calculated the radius each and every orbit of the Bohr atom - the values of the square brackets are known and n is an integer equal 1 or bigger (for n = 1 one gets the r of the first stationary orbit).
		The frequencies of radiation calculated by Bohr for the successive electron transitions is in agreement with an experimental data (the spectrum lines of hydrogen).
	library.thinkquest.org /19662/high/eng/model-bohr.html (1463 words)

	The Bohr model
		The Bohr Model is probably familar as the "planetary model" of the atom illustrated in the adjacent figure that, for example, is used as a symbol for atomic energy (a bit of a misnomer, since the energy in "atomic energy" is actually the energy of the nucleus, rather than the entire atom).
		In the Bohr Model the neutrons and protons (symbolized by red and blue balls in the adjacent image) occupy a dense central region called the nucleus, and the electrons orbit the nucleus much like planets orbiting the Sun (but the orbits are not confined to a plane as is approximately true in the Solar System).
		This similarity between a planetary model and the Bohr Model of the atom ultimately arises because the attractive gravitational force in a solar system and the attractive Coulomb (electrical) force between the positively charged nucleus and the negatively charged electrons in an atom are mathematically of the same form.
	www.angelfire.com /geek/kneekey/thebohrmodel.html (250 words)

	Bohr model of the atom
		Rutherford, who had a few years earlier, discovered the planetary model of the atom asked Bohr to work on it because there were some problems with the model: According to the physics of the time, Rutherford's planetary atom should have an extremely short lifetime.
		Bohr's model of the atom revolutionized atomic physics.
		With these conditions Bohr was able to explain the stability of atoms as well as the emission spectrum of hydrogen.
	www.iun.edu /~cpanhd/C101webnotes/modern-atomic-theory/Bohr-model.html (269 words)

	Bohr Atomic Model (Site not responding. Last check: )
		The motion of the electrons in the Rutherford model was unstable because, according to classical mechanics and electromagnetic theory, any charged particle moving on a curved path emits electromagnetic radiation; thus, the electrons would lose energy and spiral into the nucleus.
		To remedy the stability problem, Bohr modified the Rutherford model by requiring that the electrons move in orbits of fixed size and energy.
		Bohr noticed, however, that the quantum constant formulated by the German physicist Max Planck has dimensions which, when combined with the mass and charge of the electron, produce a measure of length.
	abyss.uoregon.edu /~js/glossary/bohr_atom.html (623 words)

	Bohr Model
		Thus the plum pudding model of the atom collapsed: most of the mass and the positive charge of the atom was concentrated into a very small volume.
		The wavelengths described by this formula correspond exactly to the radiation emitted when an electron in the Bohr model quantum jumps from a high energy orbit, described by some n greater than 2, to an orbit whose value of n is equal to 2.
		In the model transitions to other "final" states such as n equal to 1 or 3, 4, 5, etc. are also predicted and the wavelengths in the spectrum for these are found experimentally to exist.
	www.upscale.utoronto.ca /GeneralInterest/Harrison/BohrModel/BohrModel.html (0 words)

	Teaching Bohr Atomic Model
		Bohr's model may not explain current atom theories, but it still provides a basic understanding of atoms and how electrons behave.
		I teach lower-level high school science, and I continue to teach Bohr's model, with the caveat that it is NOT the current model.
		I tell them that even that model may change sometime in their lifetime, and that is one of the wonderful things about science and the scientific method---we keep experimenting and refining ideas.
	www.newton.dep.anl.gov /askasci/chem03/chem03658.htm (806 words)

	Atomic Physics (Site not responding. Last check: )
		The Bohr model of the atom is not the full and final picture but it is perhaps the last time we have a model we can easily picture in our minds.
		Neils Bohr was a Danish Physicist whose group in Copenhagen did much in developing and advancing the early understanding of Quantum Mechanics in general.
		Bohr proposed a model for the structure of hydrogen, the lightest and simplest atom.
	www.ux1.eiu.edu /~cfadd/1160/Ch29Atm/Bohr.html (376 words)

	Chapter Nine The Bohr Model of the Atom (Site not responding. Last check: )
		Bohr knew that light was absorbed and emitted by atoms.
		Bohr's answers to these questions were one of the first triumphs of the new Quantum Theory.
		Bohr used the ideas and principles from Quantum mechanics to suggest a model of the hydrogen atom.
	www.chem.ufl.edu /~chm2040/Notes/Chapter_9/bohr.html (525 words)

	Physicists on the Money
		Bohr was one of the main architects of the quantum theory, the basis of our understanding of the properties of matter.
		He created the first quantized model of the atom (the Bohr model) and played a major role in developing the modern interpretation of the quantum theory.
		He was the first modern scientist to propose a model of the solar system in which the sun was at the center, circled by the planets moving in orbits, but not supported by any invisible crystal spheres.
	www2.physics.umd.edu /~redish/Money (0 words)

	(Q-5) The Atomic Nucleus and Bohr's model of the Atom
		It was guessed by then that as dimensions of a motion shrank to the atomic scale, Newton's laws were gradually modified, allowing electrons to have orbits where (for some yet-unknown reason) no energy was lost by broadcasting electromagnetic waves.
		Bohr went one step further: perhaps orbits were stable when the angular momentum of the motion equaled h times some whole number.
		Adiabatic invariants occur in all sorts of periodic motions, including Kepler motion, which was taken as the model of the motion of an electron around the nucleus.
	www-spof.gsfc.nasa.gov /stargaze/Q5.htm (1714 words)

	Niels Bohr Homepage
		Bohr knew that the electrons should, theoretically, lose energy and spiral toward the nucleus until they collide with it.
		Bohr’s model of the atom proved essentially correct, and he won the Nobel Prize for his quantum theory studies in 1922.
		Bohr came up with “complementarity.” This is also called wave-particle duality, which states that certain waves, like light, exhibit characteristics of waves and particles.
	www.angelfire.com /scifi/concordiasci/bohr.html (780 words)

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