Atomic Structure Atomic Structure
The ancient Greek philosophers Leucippus and Democritus believed that atoms existed, but they had no idea as to their nature. Centuries later, in 1803, the English chemist John Dalton, guided by the experimental fact that chemical elements cannot be decomposed chemically, was led to formulate his atomic theory. Dalton's atomic theory was based on the assumption that atoms are tiny indivisible entities, with each chemical element consisting of its own characteristic atoms.âœ¶ âœ¶See Atoms article for further discussion of Dalton's atomic theory. The atom is now known to consist of three primary particles: protons, neutrons, and electrons, which make up the atoms of all matter. A series of experimental facts established the validity of the model. Radioactivity played an important part. Marie Curie suggested, in 1899, that when atoms disintegrate, they contradict Dalton's idea that atoms are indivisible. There must then be something smaller than the atom (subatomic particles) of which atoms were composed. Long before that, Michael Faraday's electrolysis experiments and laws suggested that, just as an atom is the fundamental particle of an element, a fundamental particle for electricity must exist. The "particle" of electricity was given the name electron. Experiments with cathode-ray tubes, conducted by the British physicist Joseph John Thomson, proved the existence of the electron and obtained the charge-to-mass ratio for it. The experiments suggested that electrons are present in all kinds of matter and that they presumably exist in all atoms of all elements. Efforts were then turned to measuring the charge on the electron, and these were eventually successful by the American physicist Robert Andrews Millikan through the famous oil drop experiment. The study of the so-called canal rays by the German physicist Eugen Goldstein, observed in a special cathode-ray tube with a perforated cathode, let to the recognition in 1902 that these rays were positively charged particles (protons ). Finally, years later in 1932 the British physicist James Chadwick discovered another particle in the nucleus that had no charge, and for this reason was named neutron. As a physical chemist, George Stoney made significant contributions to our understanding of molecular motion. However, this Irish scientist is better known for assigning a name to negative atomic charges, electrons, while addressing the Royal Society of Dublin in 1891. â€”Valerie Borek Joseph John Thomson had supposed that an atom was a uniform sphere of positively charged matter within which electrons were circulating (the "plum-pudding" model). Then, around the year 1910, Ernest Ruthorford (who had discovered earlier that alpha rays consisted of positively charged particles having the mass of helium atoms) was led to the following model for the atom: Protons and neutrons exist in a very small nucleus, which means that the tiny nucleus contains all the positive charge and most of the mass of the atom, while negatively charged electrons surround the nucleus and occupy most of the volume of the atom. In formulating his model, Rutherford was assisted by Hans Geiger and Ernest Marsden, who found that when alpha particles hit a thin gold foil, almost all passed straight through, but very few (only 1 in 20,000) were deflected at large angles, with some coming straight back. Rutherford remarked later that it was as if you fired a 15-inch artillery shell at a sheet of paper and it bounced back and hit you. The deflected particles suggested that the atom has a very tiny nucleus that is extremely dense and positive in charge. Also working with Rutherford was Henry G. J. Moseley who, in 1913, performed an important experiment. When various metals were bombarded with electrons in a cathode-ray tube, they emitted X rays, the wavelengths of which were related to the nuclear charge of the metal atoms. This led to the law of chemical periodicity, which provided refinement of the periodic table introduced by Mendeleev in 1869. According to this law, all atoms of an element have the same number of protons in the nucleus. It is called the atomic number and is given the symbol Z. Hydrogen is the simplest element and has Z = 1. Through Rutherford's work it was known that that electrons are arranged in the space surrounding the atomic nucleus. A planetary model of the atom, with the electrons moving in circular orbits around the nucleus seemed an acceptable model. However, such a "dynamic model" violated the laws of classical electrodynamics, according to which a charged particle, such as an electron, moving in the positive electric field of the nucleus, should lose energy by radiation and eventually spiral into the nucleus. To solve this contradiction, in 1913, the Danish physicist Neils Bohr (then studying under Rutherford) postulated that the electron orbiting the nucleus could move only in certain orbits, having in each a certain "quantized" energy. It turns out that the colors in fireworks would help prove him right. The colorful lights of fireworks are emitted by "excited" atoms; that is, by atoms that have absorbed extra energy. Light consists of electromagnetic waves, each (monochromatic) color with a characteristic wavelength Î» and frequency v. Frequency is related to energy E through the famous Planck equation, E = hÎ½, where h is Planck's constant (6.6256 x 10âˆ’34 J s). Note that white light, such as sunlight, is a mixture of light of all colors, so it does not have a characteristic wavelength. For this reason we say that white light has a "continuous spectrum." On the other hand, excited atoms emit a "line spectrum" consisting of a set of monochromatic visible radiations. Each element has a characteristic line spectrum that can be used to identify the element. Note that line emission spectra can also be obtained by heating a salt of a metal with a flame. For instance, common salt (sodium chloride) provides a strong yellow light to the flame coming from excited sodium, while copper salts emit a blue-green light and lithium salts a red light. The colors of fireworks are due to this phenomenon. Scientists in the late nineteenth century tried to quantify the line spectra of the elements. In 1885 the Swedish school teacher Johann Balmer discovered a series of lines in the visible spectrum of hydrogen, the wavelengths of which could be related with a simple equation: in which Î» is wavelength, k is constant, a = 2, and b = 3, 4, 5, â€¦ This group of lines was called the Balmer series. For the red line b = 3, for the green line b = 4, and for the blue line b = 5. Similar series were further discovered: in the infrared region, the Paschen series (with a = 3 and b = 4, 5 â€¦ in the above equation), and much later in the ultraviolet region, the Lyman series (with a = 1 and b = 2, 3 â€¦). In 1896 the Swedish spectroscopist Johannes Rydberg developed a general equation that allowed the calculation of the wavelength of the red, green, and blue lines in the atomic spectrum of hydrogen: where nL is the number of the lower energy level to which an electron falls and nH is the number of the higher energy level from which it falls. R is called the Rydberg constant (1.0974 x 10âˆ’7 mâˆ’1). R was later shown to be 2Ï€ 2me 4Z2/h 3c, where m is the mass of the electron, e is its charge, Z is the atomic number, h is Planck's constant, and c is the speed of light. As noted earlier, Bohr had suggested the quantization of Ruthford's model of the atom. Although he was not aware of the work of Balmer and Paschen when he wrote the first version of his 1913 article, he had incorporated Planck's constant h into his model, which turned out to be an important decision. Bohr assumed that the absorption or emission of radiation can occur only by "jumps" of the electron from one stationary orbit to another. (See Figure 1.) The energy differences between two such allowed orbits then provided the characteristic frequencies of the emitted light. Î”E = E n1 âˆ’ E n2 = hÎ½ Planck's constant h was named by Bohr the "quantum of action." Bohr's theory was in close agreement with many experimental facts regarding one-electron atoms (the hydrogen
Write the nuclear equations to represent the loss of an alpha particle by...Write the nuclear equations to represent the loss of an alpha particle by the product of b... How due to alpha emission, so net decreas in mass number is 3. Re: Write the nuclear equations Re: Write the nuclear equations to represent the loss of an alpha particle by the product Quote
Emissions problems and vacuum line sorting 74 westfaliaThe problem, just avoids having to pass an inspection" which I would do but still want to make it run with the exception of this after burner valve problem, but that is not a vacuum line."althoug after the smog and emissions will not be in my equation anymore. HOWEVER I do intend to get my vehicle to it's best
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Question:Einstein: The Real Story of the Man Behind the Theory syas that although not a 'vague' or genral theory, but a very specific, calculation oriented 'pass/fail' equation about the position of the stars, the theory was discounted by two teams of photographers, and validated by one other earlier American team. did the 'controversy' leave the question 'un-answered' or where they concerned about bias affecting the outcome from the American Astronomer Caldwell?
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"Einstein" redirects here. For other uses, see Einstein (disambiguation).
Albert Einstein, 1921
BornMarch 14, 1879
Ulm, Kingdom of W rttemberg, German Empire
DiedApril 18, 1955 (aged 76)
Princeton, New Jersey, USA
ResidenceGermany, Italy, Switzerland, USA
CitizenshipW rttemberg/Germany (1879 96)
Switzerland (1901 55)
Austria (1911 12)
Germany (1914 33)
United States (1940 55)
EthnicityAshkenazi Jewish and German
InstitutionsSwiss Patent Office (Bern)
University of Zurich
Charles University in Prague
Prussian Academy of Sciences
Kaiser Wilhelm Institute
University of Leiden
Institute for Advanced Study
Alma materETH Zurich
University of Zurich
Doctoral advisorAlfred Kleiner
Other academic advisorsHeinrich Friedrich Weber
Notable studentsErnst G. Straus
Known forGeneral relativity
Einstein field equations
Unified Field Theory
Bose Einstein statistics
Notable awardsNobel Prize in Physics (1921)
Copley Medal (1925)
Max Planck Medal (1929)
Person of the Century
Religious stanceSee Main article
Albert Einstein (pronounced / lb rt a nsta n/; German: [ alb t a n ta n] ( listen); 14 March 1879 18 April 1955) was a theoretical physicist. He is best known for his theories of special relativity and general relativity. Einstein received the 1921 Nobel Prize in Physics "for his services to Theoretical Physics, and especially for his discovery of the law of the photoelectric effect.".
Einstein's many contributions to physics include:
The special theory of relativity, which reconciled mechanics with electromagnetism
The general theory of relativity, a new theory of gravitation obeying the equivalence principle
The founding of relativistic cosmology with a cosmological constant
The first post-Newtonian expansion, explaining the perihelion advance of Mercury
Prediction of the deflection of light by gravity and gravitational lensing
The first fluctuation dissipation theorem which explained the Brownian movement of molecules
The theory of density fluctuations in gasses and liquids, giving a criterion for critical opalescence
The photon theory and wave-particle duality derived from the thermodynamic properties of light
The quantum theory of atomic motion in solids
Zero-point energy concept
The semiclassical version of the Schr dinger equation
Relations for atomic transition probabilities which predicted stimulated emission
The quantum theory of a monatomic gas which predicted Bose-Einstein condensation
The EPR paradox
A program for a unified field theory
The geometrization of fundamental physics
Einstein published more than 300 scientific works and more than 150 non-scientific works. He is often regarded as the father of Modern Physics and the greatest scientist of the 20th Century. In 1999 Time magazine named him the Person of the Century, beating contenders like Mahatma Gandhi and Franklin Roosevelt, and in the words of a biographer, "to the scientifically literate and the public at large, Einstein is synonymous with genius."
1 Early life and education
1.1 Marriages and children
2 Patent office
3 Scientific career
3.1 Physics in 1900
3.2 Thermodynamic fluctuations and statistical physics
3.3 Thought experiments and a-priori physical principles
3.4 Special relativity
3.6 Quantized atomic vibrations
3.7 Adiabatic principle and action-angle variables
3.8 Wave particle duality
3.9 Theory of Critical Opalescence
3.10 Zero-point energy
3.11 Principle of equivalence
3.12 Hole argument and Entwurf theory
3.13 General relativity
3.15 Modern quantum theory
3.16 Bose Einstein statistics
3.17 Energy momentum pseudotensor
3.18 Unified field theory
3.20 Einstein Cartan theory
3.21 Einstein Podolsky Rosen paradox
3.22 Equations of motion
3.23 Einstein's mistakes
4 Collaboration with other scientists
4.1 Einstein-de Haas experiment
4.2 Schr dinger gas model
4.3 Einstein refrigerator
5 Bohr versus Einstein
6 Religious views
10 Effect on popular culture
13 See also
16 Further reading
17 External links
Answers:Einstein's theory of general relativity was confirmed in 1919 by Arthur Eddington (a Brit, not an American, btw) during a solar eclipse.
AFAIK there was only one other observation done at the time, which was inconclusive. As a matter of fact Eddington's observation made headlines all over the world at the time, so General relativity considered pretty solid at the time.
So why did they give the Nobel to Einstein in 1921 for the photoelectric effect, a much less revolutionary discovery ? 2 reasons
1) The Nobel committee has always been cautious about novelties. This was still cutting-edge science at the time and probably nobody on the committee felt they understood it enough to be 100% for it. If the theory turned out to be wrong it would of course have been a major embarrassment.
2) Alfred Nobel's will stipulates that the prizes should be given to discoveries who confer "greatest benefit on mankind". This has led the committee to favor "practical" discoveries over purely abstract ones, and in that respect the photoelectric effect is a better choice.
Question:1. what is the maximum no. of emission lines when the excited electron of a hydrogen in n = 5 drops to the ground?
2. 3 x 10^8 phtons of a certain light radiation are found to produce 1.5J of energy. calculate the wavelength of light radiations.
3.how long would it take a radio wave of frequency 6 x 10^3 sec^ -1 to travel from mars to earth a distance of 8 x 10^7 km?
answers to any would be a gr8 help! thanks! answers given are :
2. 3978 angstrom
now how do we solve these?? 3. 4 mins 26 secs
Answers:1. n=5-->4 5,3 5,2 51 (4)
then the n=4 has three
n=3 has 2
n=2 has 1
sum =10..... We agree on the 10 yeah! the ten lines above
2. energy per photon:
1.5 J/3*10^8 = .5 *10^-8 J/photon
= 5 * 10^-9 J/photon
persumably you have table or equation to relate J/photon to wavelength - if not, send me e-mail
wavelength = hc/energy
= (6.626 x 10^-34 J*sec) *(3 * 10^8 m/sec)/(5 *10^-9J) = 3.9756 * 10^(-34 +8 +9) M * 10^10 Ang/M
= 3.9756 *10^-7 Ang
= 3976 * 10^-4 Ang
OK I am off by 10^4 so is the energy higher.
3. speed is independent of freq:
8 x 10^7 km * 10^3 m/km /(3 * 10^8 m/sec) =
8/3 *10^2 sec = 267 sec/60 sec/min = 4.45 min
(.45 min * 60 sec/min = 27 sec)
4 min 27 sec (rounding error)
Question:The Second Law of Thermodynamics (Entropy) would seem to exclude the possibility that a colder gas (CO2) that has absorbed IR in its selective bandwidth of IR could possibly emit IR back to a warmer gas (CO2) that may or may not already be saturated and excited into its highest energy state. In a colder gas CO2 still drops from its excited state to normal by a combination of re-emission of IR and losses due to kinetic energy. The lost IR, if moving downward, in a static column of atmosphere, is portrayed as being recaptured with the same bandwidth emission of IR in what would be a warmer and probably saturated (within the absorptive bandwidth for IR) molecule of CO2.
Can anybody explain to me how such a mechanism does NOT violate the Second Law of Thermodynamics?
The only answer I received from the AGW section of YA is that I misunderstand "grey body" theory. I may misunderstand grey body theory, bit I do know that it can never involve a violation of the Second Law. How do the physicists get around this obvious problem?
If the lower layers of warmer atmosphere do not actually absorb any IR from above, then the only radiative imbalance from this downward re-radiated IR would be the imbalance created by the transparent IR being reflected back upward like a mirror from the original pseudo "black body" radiator...the Earth. This would mean that the warming effect has a distinct "decay" similar to the 1/2 life of radiation in radioactive materials?
What am I missing here??? Thank You Lee Wang but my quantum Physics is lacking (35 years out of University and I was glad to see the end of Physics before getting my Geology Degree). What are the initial Terms in your equation prior to T Initial and Final ? Definitions?
I am still confused as to my gas analogy since CO2 at high temperature is lower in the Troposphere and saturated with IR in its absorption bandwidth. Higher Tropospheric CO2 may or may not also be saturated but it is cooler because of Lapse Rate (5 degrees C per 1000 meters). The lower tropospheric CO2 has a lower entropy than the higher and cooler CO2 so therefore the net IR radiation must always be upward in the atmosphere and never downward toward a reduced (lower entropy or stated otherwise toward a more excited molecular energy state). NASA shows nicely radiating balls of CO@ which radiate their IR radially away from any CO2 molecule, however this must be a bit of a misrepresentation since the NET IR is going to be upward! Explain?
Answers:Yes it can.
I think when we talk about mode of heat propagation by radiation it is not forced by the difference of temperature or you said as cold body or warmer body. The temperature of equation of black body radiation ( . .A[Tf^4 -Ti^4]) only counting the net of energy disposition as heat, in or out.
As we know almost every process required different energy and or different entropy for the process could really happen. Perhaps we can use the sun and earth as object.
The sun at it surface has temperature approximately 5000 deg C. It radiates Electromagnetic wave with E = hf1. The motivation of this electromagnet propagation is that the electron is being "bigger" with energy, so electron tries to equalize and back to its orbit, to do that it release a certain amount of photon. And every object which still absorb energy and gain finite temperature will release its excessive energy.
As for our earth also release and radiate IR energy, E = hf2. f2 has lower frequency than f1.
Tf and Ti, means temperature of the system and average temperature of the surrounding. It means there are energy(IR) emission from the system and absorption to the system. The system refer to any object including CO2 molecules.
If the nett energy of absorption is bigger or the average temperature of surrounding is higher than the temperature CO2, then the CO2 molecules receive energy.
For CO2 gas, which receive IR radiation, whether it cold or warmer as you said, the entropy of that gas will increase. It happens if the average temperature of surrounding is higher. When this happen and the CO2 is not saturated, the temperature must going higher for certain degree.
From Tds equation
sf-si = Cp ln (T2/T1) - R ln (p2/p1), with contant pressure.
The entropy must increase which is not violate the 2nd law of thermodynamic. The bandwith of CO2 gas depends on its temperature, as described by Wien's displacement law. http://en.wikipedia.org/wiki/Wien's_displacement_law
The Physics of Anti-GravityRichard Feynman once said "It doesn't matter how smart you are, or how brilliant your theory is. If it doesn't agree with experiment, it's WRONG!" I'd really like to see if this theory is wrong, but I don't think it is. At least until someone can show me how and why it fails. So far it's only given right answers. You get the Compton wave of the electron, the radii and intensities of spectral emissions, and it explains why everything looked so confusing through the only lenses which 1930s science permitted. The mathematical achievements of the past century are astounding in retrospect to such a simplified theory of quantum mechanics. Yet the math gives us real answers, and tells us these abstract hyperdimensional modelings was just the speed of light refracting into the electron shell which behaves like a Bose Condensate. The first Bose Condensate wasn't created until 2003, the great scientists never performed experiments with large diameter rotating superconductors, so how could they possibly have known or seen this??? The Original Paper: www.scribd.com A-reconciliation-of-Quantum-Mechanics-and-Special-Relativity: www.scribd.com Frank Znidarsic "The Duality of Matter and Waves": www.scribd.com Background and additional info: en.wikipedia.org en.wikipedia.org Schrodinger and Dirac Equations: en.wikipedia.org en.wikipedia.org Bose-Einstein Condensate: en.wikipedia.org Harvard Bose Condensates stop and restart light: www.news.harvard.edu Frank Znidarsic: "I was part of the ...
The Fabric of Space-Time an artist theory.This video will give you an artist view of the Fabric of Space-Time explaining the paradoxes of quantum physics including the Two Slit Experiment as a process that is continuously unfolding in time. This will be based on the equations and calculations that we already have and will fit in with the reality of our everyday life. The physicist Richard Feynman once said that we understand how to do the calculations but we don't understand why we have to do the calculations. I have always found this very odd and this very simple theory is the complete opposite and can be understood visually by anyone and this is part of the beauty of the theory. In this theory the flow of time is formed by the continuous inward absorption and outward emission of light or EMR. In a very similar way that we use sound wave to create our own music we use light waves to create our own future time that will have the geometry of spacetime. The wave-particle duality of light is continuously forming a blank canvas for the observer that he or she can participate in! In this theory the fabric of Space-Time is formed by an infinite number inertial and non-inertial reference frames that all have their own proper time relative to their momentum and position. The beauty of light is a wave in reflection, refraction, diffraction and in Maxwell's equations! Only when the light comes in contact with an object is it a particle or photon of quantized energy as in the photoelectric effect. Then the inward absorption ...
Albert Einstein Original FootageAlbert Einstein (14 March 1879 18 April 1955) was a German-born theoretical physicist. He is best known for his theory of relativity and specifically massenergy equivalence, expressed by the equation E = mc2. Einstein received the 1921 Nobel Prize in Physics "for his services to Theoretical Physics, and especially for his discovery of the law of the photoelectric effect." Einstein's many contributions to physics include his special theory of relativity, which reconciled mechanics with electromagnetism, and his general theory of relativity, which was intended to extend the principle of relativity to non-uniform motion and to provide a new theory of gravitation. His other contributions include advances in the fields of relativistic cosmology, capillary action, critical opalescence, classical problems of statistical mechanics and their application to quantum theory, an explanation of the Brownian movement of molecules, atomic transition probabilities, the quantum theory of a monatomic gas, thermal properties of light with low radiation density (which laid the foundation for the photon theory), a theory of radiation including stimulated emission, the conception of a unified field theory, and the geometrization of physics. Einstein published over 300 scientific works and over 150 non-scientific works. In 1999 Time magazine named him the "Person of the Century". In wider culture the name "Einstein" has become synonymous with genius, and he has since been regarded as one of the ...
Thoughts From Albert EinsteinA few jewels of wisdom Albert Einstein thought and spoke that we can understand. How ironic that Einstein, who was a devout pacifist, would discover E=MC2 an equation that would lead to the largest weapon of war ever constructed, the atomic bomb. Einstein's many contributions to physics include his special theory of relativity, which reconciled mechanics with electromagnetism, and his general theory of relativity, which extended the principle of relativity to non-uniform motion, creating a new theory of gravitation. His other contributions include relativistic cosmology, capillary action, critical opalescence, classical problems of statistical mechanics and their application to quantum theory, an explanation of the Brownian movement of molecules, atomic transition probabilities, the quantum theory of a monatomic gas, thermal properties of light with low radiation density (which laid the foundation for the photon theory), a theory of radiation including stimulated emission, the conception of a unified field theory, and the geometrization of physics. You are an integral and unique part of the universe. Just as important a part as any other part. There is no one else exactly like you. No one else has your fingerprints, your exact DNA, your exact thoughts or dreams. You are connected to everything and everything you do affects the rest of creation. Try to make the universe a better place.