What is Atom: Definition and 999 Discussions

The name Atom applies to a pair of related Web standards. The Atom Syndication Format is an XML language used for web feeds, while the Atom Publishing Protocol (AtomPub or APP) is a simple HTTP-based protocol for creating and updating web resources.Web feeds allow software programs to check for updates published on a website. To provide a web feed, the site owner may use specialized software (such as a content management system) that publishes a list (or "feed") of recent articles or content in a standardized, machine-readable format. The feed can then be downloaded by programs that use it, like websites that syndicate content from the feed, or by feed reader programs that allow internet users to subscribe to feeds and view their content.
A feed contains entries, which may be headlines, full-text articles, excerpts, summaries or links to content on a website along with various metadata.
The Atom format was developed as an alternative to RSS. Ben Trott, an advocate of the new format that became Atom, believed that RSS had limitations and flaws—such as lack of on-going innovation and its necessity to remain backward compatible—and that there were advantages to a fresh design.Proponents of the new format formed the IETF Atom Publishing Format and Protocol Workgroup. The Atom Syndication Format was published as an IETF proposed standard in RFC 4287 (December 2005), and the Atom Publishing Protocol was published as RFC 5023 (October 2007).

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  1. S

    Kinetic Energy & Uncertainty of He-3 Atom Recoil in T Decay

    When a T atom decays into He-3 atom ground state, what is 1) the kinetic energy of its recoil energy and 2) the theoretical uncertainty of that energy? The beta decay energy of a triton is something like 18 500 eV. When (most of time) a free electron is emitted, its energy can acquire any...
  2. DiracPool

    Coulomb potential in hydrogen atom nomenclature

    I'm seeing a version of the potential as -Ze^2/4πεr. My question is what exactly does the Ze^2 refer to? I think the e^2 is supposed to represent the proton and the neutron, and the Z is supposed to represent the number of protons, but I'm not sure how to read it. Does e refer to the charge...
  3. greasehoot

    Formula for the vibration rate of an atom?

    Just a general inquiry, and not for any personal gain and or theory, I would like to know if anyone has developed a formula for measuring the vibrational rate of an atom.
  4. J

    Electromagnetic emission lines for a hydrogen atom

    Homework Statement Hi, I've been unable to find a relevant thread for a question that I've been stuck on for a couple of days now. Here it is; One of the electromagnetic emission lines for a hydrogen atom has wavelength 389nm. Assiming that this is a line from one of the Lyman (nf =1 )...
  5. Y

    Can Light Be Stretched in a Lab? Exploring Doppler Shift & X-Rays

    Is it possible to create a doppler shift of EM radiation in a lab? or is it only feasible on universal scales? I was just thinking that high energy x-rays have a sub-atomic wavelength,could these be transformed to visible light to let us 'see' an atom?
  6. N

    How do electrons orbit the nucleus?

    I have heard that instead of orbiting the nucleus they actually pop into and out of existence around the nucleus forming the electron cloud, and where they relocate depends on the probability of that area due to wave function, am i right?
  7. N

    Every known element has a unique atom?

    This notion perplexes me. Could I please have this explain with an example(s). I am confused are atoms not made up of the same protons and neutrons which are just essentially negatively or positively charged particles which are made of quarks? Which as confusing as that can become. How can one...
  8. T

    Hydrogen Atom orbital and quantum number

    I am wondering and have been thinking, exactly how does the energies of hydrogen atom orbital depend on quantum numbers? I am just curious because all of what I have learned/read discusses only one-dimensional situaiton, like a particle in a box, and I want to know how it can be applied to the...
  9. B

    Atom or weight fraction in MOX fuel

    Hi. I have a problem with some calculations. I have to find atom or weight fraction in MOX fuel. MOX fuel is a mixture of UO2 and PuO2. It can be mixed with a various enrichment of PuO2. The fraction of isotopes of uranium and plutonium are as here: U234 234,041...
  10. K

    Planck's Constant and the size of the atom

    Homework Statement [/B] If Planck’s constant were smaller than it is, how would the uncertainty principle be affected and how would the size of atoms be affected? Homework EquationsThe Attempt at a Solution I know this question has been kind of asked before in this forum but an answer was...
  11. B

    Energy levels and hydrogen atom

    if you take a hydrogen atom and strip off the electron so that you are left with a proton. does the proton have energy levels around it? can a solitary proton still be regarded as an atom (H+)
  12. Seydlitz

    Effect of different atom on Compton Shift?

    Hi guys long time no see, I'm having a small difficulty here in understanding the process. Looking at the equation and the derivation of it, it seems clear that the shift in wavelength can only be caused by the target mass. If we are talking about electron being hit by x-ray, then I take it...
  13. D

    Ion or Neutral Atom? AI Decays Into Stable Si

    Homework Statement An atom of 28_13 AI decays into stable nuclide 28_14 Si by emitiing a beta particle. What's 28_14 Si ? the ans given is positive ion? in my opinion, it should be a neutral atom... which is correct? Homework EquationsThe Attempt at a Solution
  14. D

    Energy Req'd to Remove Nucleon from 12_6 C Atom

    Homework Statement lets's say the binding energy of 12_6 C atom is 2.00MeV .. what's the energy required to remove a nucleon form the 12_6 C atom Homework EquationsThe Attempt at a Solution is it 2.00MeV or 2.00MeV / 12 ? binding energy is defined as the energy required to separate all the...
  15. kelvin490

    Coating Hollow Shapes w/ Vacuum Evap: Atom vs Ion?

    Is it possible to use vacuum evaporation, sputtering and ion plating processes to coat the inside walls of holes and other hollow shapes of substrates? I wonder whether the source materials are ejected in the form of atoms or ions? Many books say atom but how can they travel to the substrate if...
  16. J

    Speed After Collision of Proton & Carbon Atom

    A proton is traveling to the right at 3.50×107 m/s. It has a head-on perfectly elastic collision with a carbon atom. The mass of the carbon atom is 12 times the mass of the proton. What is the magnitude of proton speed after the collision? What is the magnitude of carbon atom speed after the...
  17. D

    Interaction between light and hydrogen atom

    If a symmetric distribution of charge has no electric dipole moment, where does the \mu term we write in the part of the hamiltonian representing interaction with light come from? We suppose it is induced by the electric field of the light?
  18. W

    How many times does a atom excitate when light shines onto it?

    Noob question ahead. So basically I'm reading about atoms and photons in my textbook at the moment and I came across excitation and why atoms emit photos with certain wavelengths when hit by white light. The claptrap doesn't really matter, what I'm confused and curious about is how many times...
  19. B

    How Did We Develop Early Models of the Atom?

    In my studies, I find myself coming back to the same question.How do we know all these things about matter. Its quantized, it has mass and, charge and blah blah blah. I understand that these models of the building blocks of "physical things" are well tested mathematical models that attempt to...
  20. V

    Is the Energy Change in a Bohr Atom Always Equal to One Photon?

    From Wikipedia, the following diagram explains the energy emitted when an electron jumps from a higher-energy shell to a lower-energy shell: I already know that the energy of a single photon is equal to ##hf## and in this diagram, ##\Delta E=hf##. Does that mean that ##\Delta E## is only one...
  21. avito009

    The mass of the atom is due to the energy of strong force. So it is energy and not mass right?

    The mass of the nucleons (and, by extension, most of the visible universe) is caused by the energy stored up in the force field of the strong nuclear force. Please Explain this to me in layman's terms. I would appreciate the help. (I am being polite because phinds said so). How does the energy...
  22. W

    Absorption of a photon by atom - where does the energy go?

    I recently thought about this. Let's say there's a hydrogen-like atom with a transition energy \omega. If it is hit with a photon of frequency \omega, it will make a transition to the excited state, so the change in internal energy is \omega. But by conservation of momentum, the atom will also...
  23. L

    Uncertainty principle for electron inside atom

    Homework Statement Hopefully it is not a faux pas to post two questions relatively close together in time. This is more of a conceptual question than a calculation based question. An electron is confined to a region of space of the size of an atom (0.1 nm). a) What is the uncertainty in the...
  24. 2

    Deriving the ground state energy of a hydrogen atom?

    Homework Statement Hello! I am trying to derive the ground state enegry of a hydrogen atom, and have come to U=\frac{-mk_{0}^{2}Ze^{4}}{n^{2}\hbar^{2}} Problem is, I know there should e another factor of 2 in the denomenator because I get the ground state energy of hydrogen as being 27.145eV...
  25. M

    Electron Transition & Photon Emission in Hydrogen Atom

    How an electron transition from lower energy state to higher energy state in hydrogen atom emits a photon?
  26. Simon = Mc2

    Building an Atom Smasher: Cost, Materials, and Design

    Like the cost, material, design ext...
  27. T

    Particles on the surface of an atom?

    There are many particles inside an atom. What particles make up the surface of an atom? When we see graphical illustrations of spherical atoms, what are we actually seeing?
  28. J

    Positron to replace proton as the nucleus of an atom

    I know that the positron and electron have the same mass, which allows them to annihilate, and I know how solve the 2 body Schrodinger for a standard hydrogen atom to get the orbitals. My question is why the math works out the way it does. Is there an "intuitive" (I use that word cautiously)...
  29. AllenJH

    Displacement energy of atom in a liquid (for ion implantation)

    Hi Physics Forums! I'm a bit stuck here. I'm fairly sure I intuitively know the answer here, but am looking for harder proof. The following question is in regards to my current research work (materials sci/eng). Does anyone know of a discussion of the displacement energy of an atom in a...
  30. O

    What experiment reveals the number of protons and neutrons in an element?

    Assume that I have a sample of an element which is electrically neutral, I want to know the number of protons, and neutrons in atoms of this element. What kind of experiment should I do? In other words, how did they know the number of protons and neutrons of elements when they were forming the...
  31. M

    Can we "fill" an atom with alpha particles?

    The following passage has been extracted from the book "Modern's abc of Chemistry": Lets fill an isolated atom by subatomic "Rutherford projectiles"-alpha particles. I hope it is possible. This doesn't seem to be a limit of our technology. Isn't it? If we are successful in...
  32. S

    A photon absorption/emission by an atom

    Hello, I am wondering about a photon absorption/emission by an atom. We have been told at the university an electron is excited up in Bohr's model if an atom absorbs an energy in a form of photon. What cause an electron release an energy and falls down in Bohr's model? Does not an atom...
  33. C

    Electron orbital velocity in hydrogen atom?

    Are there any actual numbers for electron orbital velocity in hydrogen atom?
  34. T

    Brainfarting reading Griffiths QM (small step in solving Hydrogen atom

    I can tell this is simple, but I'm just not seeing it: (pages 146-147) Radial equation = d^{2}u/dp^{2} = [1 - p_{0}/p + l(l+1)/p^{2}]u Later... (having stripped off the asymptotic p^{l}e^{-p} parts) d^{2}u/dp^{2} = p^{l}e^{-p}{[-2l-2+p+l(l+1)/p]v + 2(l+1-p)dv/dp + p*d^{2}v/dp^{2}} And he...
  35. Phy_enthusiast

    Proof for quantisation of electrons energy around an atom?

    What is the proof for quantisation of electrons energy around an atom?
  36. K

    Why is Bohr's model of an atom limited to explaining only the hydrogen spectrum?

    Why is Bohr's model of an atom not able to explain the spectrum of atoms other than hydrogen? Can you give an example? :what:
  37. C

    Discovery of the atom, electron etc. Where are the experiments that pr

    Hi, I find it sad that textbooks state JJ.Thomsons, Rutherfords, Milikan, Borhs etc. discoveries as facts without actually showing the whole experiment and showing in detail how they performed the experiment and how they derived their equations. Are there any textbooks that actually do this? I...
  38. U

    Trying to calculate how <r> in the Hydrogen atom changes with time

    I am working on the Hydrogen atom and I was trying to calculate \frac{d<r>}{dt} using \frac{d<r>}{dt} = \frac{i}{\hbar} <[\hat{H} , \hat{r}]>. Here r = \sqrt(x^2 + y^2 + z^2) and H = \frac{p^2}{2m} + V where p^2 = -\hbar^2 \nabla^2 . Now according to Ehrenfest's theorem <r> should behave...
  39. B

    Why Do Electrons Determine Atom Volume While Nucleons Account for Mass?

    The Volume of an atom comes from its electrons and mass of an atom comes from its nucleons. I don't understand why? Any one can explain it please? Thanks in advance
  40. H

    Nature of Electrons inside an atom

    Hi, I am reading about the quantum model of the atomic structure, and recently encountered the Schrödinger’s model. However I am a bit confused about the nature of the electrons. Can we think of an electron a wave or as a particle when it is inside an atom? I know that in Schrödinger’s...
  41. F

    How Does IBM Manipulate Atoms and What Are the Implications for Data Storage?

    I have a number of questions about the above video: What are they using to move the atoms? What are the wave-like lines around the shape/atoms? Why can't we see the atoms of the material that the video was filmed on (i.e. the background)? Side question - What do atoms have to do with data...
  42. K

    How Is the Diameter of an Iron Atom Calculated?

    Homework Statement 55.847 grams of iron contain NA=6.02E23 atoms. the density is ρ=7.87 [gr/cm3]. What is the diameter of the iron atom Homework Equations The Attempt at a Solution The volume of 55.847 grams is: $$\frac{55.847}{7.87}=7.1[cm^3]$$ I assume the NA number of atoms is...
  43. V

    Hydrogen Atom in homogeneous magnetic vector potential

    Hey! I did an quantum mechanical analysis of a Hydrogen Atom in a homogeneous magnetic vector potential (I know that it might be impossible to create this kind of field) out of curiousity. I showed it to some professors of mine, but they all said that they don't have time. So I decided to post...
  44. BrainMan

    Conservation of momentum uranium atom problem

    Homework Statement A uranium atom of mass 238 u decays by emitting an alpha particle (the nucleus of a helium atom) of mass 4 u at a speed of 2 x 107 m/s. (Note that "u" is the symbol for atomic mass units and 1 u = 1.67 x 10-27 kg.) What is the recoil speed of the resulting nucleus immediately...
  45. J

    Force and acceleration on sodium atom if laser bundle shines on atom

    Homework Statement I want to calculate the average force and acceleration on an sodium atom, if a laser bundle shines on it which has I>>>> I(sat). I(sat) is the saturation intensity of the 589nm 3s-3p transition in sodium. 3p lives 16 ns Homework Equations c = 3 * 10 ^ 8 m...
  46. 1

    Is it Possible to Spin an Atom without Breaking it Apart?

    i mean, people are creating LHC to split the atoms, but why don't we just spin it? spin in in high speed and see if a quark/photon/electron would break can we not do that? is it mathematically impossible to have a mass in the center of rotation?
  47. R

    What is the internal and external quantum numbers of a atom

    I am reading a book about the interaction between atom and photon. I don't understand the following statement: "for the sake of simplicity, we assume the atom to be infinitely heavy and disregard the external quantum numbers" Q: what is the external (or internal) quantum number of an atom.
  48. gfxroad

    Charge q located a large distance from a neutral atom

    Homework Statement A point charge q is situated a large distance r from a neutral atom of polarisability α. Find the force of attraction between them. Homework Equations \vec{E}_{mono}(r)=\frac{q}{4\pi\epsilon_0r^2}\hat{r}...
  49. gfxroad

    Interpreting Hydrogen Atom Wave Functions: A Question of Correctness?

    Homework Statement I solved the Schrödinger equation, obtaining a wave function in terms of Radial and the spherical harmonics as follows: $$Ψ(r,0)= AR_{10} Y_{00} + \sqrt{\frac23} R_{21} Y_{10} + \sqrt{\frac23} R_{21} Y_{11} - \sqrt{\frac23} R_{21} Y_{1,-1}$$ Homework Equations...
  50. B

    Atom Absorbing and Emitting Photons

    Homework Statement Consider a pretend atom for which the electrons can be in anyone of the following energy states: Label Energy A -1.400×10-18J B -8.000×10-19J C -5.000×10-19J D -3.000×10-19J Start by arranging the four levels on a graph, then answer the following questions...
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