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).

View More On Wikipedia.org
Recent contents Top users
  1. L

    Vector model of atom. Hopefully easy question.

    In system with one electron total angular moment vector ##\vec{j}## is just: \vec{j}=\vec{l}+\vec{s} http://selfstudy.in/MscPhysics/BScVectorModelOfAtom.pdf In page 3 author draw a triangle. Intensities of the vectors are ##|\vec{l}|=\sqrt{l(l+1)}\hbar##, ##|\vec{s}|=\sqrt{s(s+1)}\hbar##...
  2. Roodles01

    Total energy of Coulomb model of Hydrogen atom

    Homework Statement Hi, my question is regardng a Coulomb model of an H atom specified with Hamiltonian operator, Hhat, by spherical coordinates of energy eigenfunction ψ2,1,-1 (r,θ, ∅) =(1/ 64∏a02)1/2 r/a0 e-r/2a0 sinθ e-iθ Principal quantum numer n = 2 orbital an mom l = 1 magnetic...
  3. N

    Can a single atom have a temperature?

    I know temperature is the measure of how much atoms are moving, so can a single atom even have a temperature? The quarks inside the protons and neutrons are moving around, so?
  4. U

    Understanding Hybridization in Central Atoms: NH3, SO2, and NH4+

    http://img577.imageshack.us/img577/2892/3kow.png both NH3 and SO2 and NH4+ have hybridization sp3
  5. R

    Write the inner product of the state vector in a atom orbital

    Consider 2 atomic orbitals with wave function a: σ(r), b: μ(r) in a diatomic molecules. σ(r) (or μ(r)) is localized around an atom a (or b) and is relevant for the discussion of the molecular orbital. These orbitals are orthogonal and normalised. The creation operators are x, y and vacuum, |0>...
  6. D

    Total angular momentum of atom in its ground state

    Homework Statement The question is to find the total angular momentum of the following atoms in their ground state - Na (11 electrons), and Rb (37 electrons). That's all the info given. Homework Equations I have no idea - that's what I can't find! The Attempt at a Solution I've...
  7. D

    Exploring Selection Rules for Hydrogen Atom

    I have a couple of questions about selection rules for the hydrogen atom. When we talk about these rules in an undergraduate context we are usually assuming LS coupling where we ignore spin orbit coupling so orbital and spin angular momentum are essentially independent. Is that correct...
  8. jfizzix

    How is the energy of an electron lost in a classical hydrogen atom?

    Consider the following. You have an electron of negative charge orbiting a proton of positive charge at some distance R (i.e. a classical hydrogen atom). I understand the hydrogen atom is unstable under classical physics because the accelerating electron loses its kinetic energy as...
  9. K

    Exploring the Energy Difference of a Hydrogen Atom in a Magnetic Field

    Homework Statement • Consider a hydrogen atom in its ground level, placed in a magnetic field of 0.7 T along the z axis. (a) What is the energy difference between the spin-up and spin-down states? (b) An experimenter wants to excite the atom from the lower to the upper state by sending in...
  10. J

    Quantum Electron Energy Level for Hydrogenic atom

    1. Consider doubly ionized Lithium (Li++), which has one electron orbiting a +3 charge nucleus. Assuming the electron is in the ground state (n=1), what is the maximum wavelength of light, λ, that would completely ionize the Li++? (free the electron from the nucleus), all variables and...
  11. K

    Calculating Mass Difference in H Atom from Proton & Electron

    Homework Statement If an electron and proton (both initially at rest and far apart) come together to form a hydrogen atom, 13.6 eV of energy is released (mostly as light). By how much does the mass of an H atom differ from the sum of the electron and proton masses? What is the...
  12. K

    Electric Potential Problem Involving Uranium Atom

    Hi Everybody, I am currently battling with the fourth and final question of my A Level physics work for this week. The problem has been driving me crazy, as I seemed to have completed all of the relevant steps, and I find the right answer only with negative exponents, which isn’t much help at...
  13. T

    Atom when electrone is bombarded inside the nucleus

    what will happen TO THE ATOM if electron end up inside the nucleus ( as in quantum tunnelling) ?
  14. A

    Atom distance and repulsive energy

    I'm had this class yesterday that I did'nt understand anything, I have exam on two days and I started to study by myself about potential energy so, I found this equation: Ue(r) = q1 q2/4πε0r + repulsive energy (same as van der Waals) where q1 = -q2 and each q = + or - 1.6E-19 C and...
  15. D

    What is the velocity of the hydrogen atom after absorbing the photon?

    A stationary hydrogen atom with a mass of 1.67 x10^-27 kg absorbs a photon of light with an energy of 10.2eV.What is the velocity of the hydrogen atom after absorbing the photon? This is my question: Is it true that the atom has no speed since all the energy is completely absorbed at the...
  16. R

    Photon emission by an excited hydrogen atom

    Typically (in popular literature) the process of photon emission by an excited atom is considered as an instant event. But actually it is quite likely that it is a continuous process. Such processes are usually described by evolutionary differential equations (ODEs or PDEs). Assume that we...
  17. A

    Einstein notion of time and the oscillation of the cesium atom

    I just read the thread entitled: "How did Einstein Define Time" and I'm very confused. At school, I was taught that time was an abstract representation of movement meaning that the word "time" can only be used to represent movements. For example, when Earth has completed a cycle around the...
  18. S

    Can a neutral atom be affected by magnetic field?

    If we have a moving, neutral atom, say hydrogen, will it react to a magnetic field? If yes, why? If you ask why not, I argue that the atom as a whole is a chargeless entity.
  19. N

    A single atom in a cold, closed, vacuum system.

    Let us assume there is a single atom in a vacuum chamber which is kept at near absolute zero. Now assume the system is closed and that the chamber is large enough such that the atom cannot diffuse far enough to reach the walls. Neglecting other stochastic effects, what do you think the atom's...
  20. Q

    Acceleration operator and the electron in a hydrogen atom

    I am wondering about acceleration in quantum mechanics. Let's consider spherically symmetric potential V(r). From the Heisenberg equation of motion, one finds the time derivative of the momentum operator \dot{\hat{p}}=\frac{i}{\hbar}\left[\hat{H},\hat{p}\right] = -\nabla V, from which we can...
  21. 4

    The strength of electromagnetism in an atom?

    I realize atoms are held together by STRONG electromagnetism, but if you were to convert this energy into an everyday scenario, how strong would it really be? I'm trying to explain the power behind a small atom and I feel using a 'real', known object. Thank you in advance for any answers.
  22. V

    What is the <r> for a hydrogen atom in n=2, l=1, m=0 state?

    Homework Statement Hydrogen is in n=2, l=1, and m=0. Wave function is ψ(r,θ,∅)=(1/4(√2pi)ab3/2)(r/ab)(e-r/2ab)(cos(θ) Find <r> for this state. Homework Equations P(r) = 4pir2|R(r)|2 <r> is equal to the integral from 0 to ∞ of P(r)dr The Attempt at a Solution I understand...
  23. D

    Uncertainty Product for a hydrogen-like atom,

    Homework Statement Calculate the uncertainty product ΔrΔp for the 1s electron of a hydrogen-like atom with atomic number Z. (Hint: Use <p> = 0 by symmetry and deduce <p^2> from the average kinetic energy) Homework Equations All I have is the wavefunction. For a 1s, it takes the form...
  24. B

    Hydrogen Atom Shells: Inner & Outer Electron Shells?

    Do hydrogen atoms have inner and outer electron shells? I saw a diagram somewhere that showed a carbon atom with an inner and outer shell, is this proven? Are these shells magnetic or something else? Do you consider the outside of these shells as the diameter of the atom?
  25. L

    Hydrogen atom. Simple question I think.

    When you solving Sroedinger eq for hydrogen atom you get energy values ##E_n\approx \frac{1}{n^2}##. Why for some value of this energy electron don't leave atom?
  26. M

    MO Diagram from Group Theory: Central Atom

    Homework Statement I am wondering how for determine the central atom's orbitals from the point group character tables described by group theory. For example CO3^-2 (D3h) Carbon's (central atom) p-orbitals are described by a1''+e'. The s-orbital is a1' Homework Equations The...
  27. M

    Contributions Per Atom in MO diagram

    Homework Statement How do you find the contributions per atom for calculating the reducible parts? For example CO3-2 has pt. grp: D3h. From the character tables-- the first row (unshifted atoms) is: 3,0,1,3,0,1. Second row (coefficients): 1,2,3,1,2,3 Third Row (contributions per atom)...
  28. robphy

    IBM's A Boy And His Atom: The World's Smallest Movie

    IBM's "A Boy And His Atom: The World's Smallest Movie" https://www.youtube.com/watch?v=oSCX78-8-q0 ...how it was made www.research.ibm.com/articles/madewithatoms.shtml
  29. F

    Hydrogen atom probability of electron inside nucleus

    Homework Statement The ground state of the hydrogen atom has the wavefunction: \psi (r) = \frac{1}{\sqrt{\pi}} (\frac{1}{a_{0}})^{\frac{3}{2}} e^{-r/a_{0}}, where a_{0} = 0.53Å a) Calculate the probability that an electron will be found inside the nucleus of the hydrogen atom, which is...
  30. sunrah

    Statistical operator of hydrogen atom

    Homework Statement Individual hydrogen atoms have been prepared in the energy state n = 2. However, nothing is known about the remaining quantum numbers. Fine structure and all corrections can be ignored. What is the micro-canonical statistical operator. Homework Equations \hat{\rho_{mc}} =...
  31. J

    What is the true nature of an atom and how can we visualize it?

    Hi, I am a graphics programmer / animator and would like to play around and try to visualize an atom. I think I can do better than the run of the mill spheres or blobs as they are normally portrayed. I have a decent physics background, I know QED by Richard Feynman by heart, and I have...
  32. T

    What is the relation between Ultra-cold atom and optical lattice?

    Ultra cold atom is achieved by laser cooling. For optical lattice, it is achieved by the interference of counter-propagating laser beams. What is the relation between Ultra-cold atom and optical lattice? Why do people load Ultra-cold atom in optical lattice? Thank you for your answer.
  33. A

    Principal Quantum Number of the Excited Oxygen atom.

    Normally, Oxygen has 8 electrons in its neutral form that is 1s2 2s2 2p4. In this case, its principal quantum number (n) is two. But what happens if it got excited and its electronic configuration becomes 1s2 2s2 2p3 3s1? In this case, Is the principal quantum number (n) of oxygen two or...
  34. C

    How to find the ground state of He atom

    Hello PF members, I am trying to solve for helium atom ground state by using perturbation theory. It is very easy to calculate the first order correction of ground state energy but I have no idea for how to find its wave function. I have tried to use the first order correction formula for wave...
  35. C

    Absoprtion specrum, identifying the 1 electon atom

    Homework Statement The energies of some transitions observed in the absorption spectrum of an unknown one electron ion ( eg He+) are listed. Given that these transitions originate from the lowest energy level suggest an identification of the unknown ion UNKNOWN ION (CM^-1) 1646254.1...
  36. E

    RMS displacement of a diatomic atom

    Homework Statement A hypothetical atom is diatomic containing two identical atoms separated by an equilibrium distance. About this distance the atoms vibrate with the electric forces providing an effective spring constant of k = 4.0×10^−3 N/m. As the temperature of the sample is increased the...
  37. S

    Why will chlorine atom attract electron.

    Homework Statement Suppose that there is an isolated chlorine atom and there is an isolated electron in its surroundings. Then what force will act on the electron to pull it towards the atom. Homework Equations The Attempt at a Solution I know that chlorine will attract the...
  38. E

    Calculating Electric Fields for H Atom Ionization with SFA

    Hi! I have some trouble with atomic unit. I have a laser pulse with the wavelength of ##800 nm## at the peak intensity of ##1.0*10^{14} W/cm^{2}##. I'd like to calculate the corresponding electric field ##E_0##. I use the formula ##I=0.5Cε_0{E_{0}}^2## and ##1 a.u.=5.14*10^{11} V/m## to obtain...
  39. U

    What is the excitation energy of an atom after a photon collision?

    Homework Statement There's an elastic collision between a photon of energy E and an atom in an excited state. After the collision, the energy of the photon is still E but its direction changed of angle of 180° and the atom is now going back with velocity Bc. If the atom is in his ground state...
  40. M

    Nuclear Reactors, Atom Smashers, and Particle Accelerators

    What would be the difficulty of building each? I have read of Michio Kaku building an atom smasher (albeit it ruined the power flow to his house,) I have found a 200,000 volt generator so I presume that a particle accelerator would be possible, and my friend is currently working on a nuclear...
  41. C

    Why is chlorine the central atom in a chlorate ion

    I know that when you draw the lewis structure for chlorate, the chlorine goes in the center with the oxygen bonded to it. What I don't understand is that the teacher told me that the central atom is the element with the fewest valence electrons. So wouldn't that make oxygen the central atom...
  42. J

    Phase of photon from excited atom

    Imagine that an excited hydrogen atom in the symmetric 2s state emits a photon. We use a birefringent crystal to split the photon into vertical and horizontal components. Is the phase relation between these components random or is it the same for every photon emitted by a similarly excited...
  43. E

    Preferred direction about hydrogen atom

    When solving the three dimensional Schrödinger equation, we obtain a probability distribution on θ. But it seems like the procudure produces a particular direction the z-axis. While the Coulomb field is spherical symmetric, it shouldn't exist such a preferred direction. I'm puzzled.
  44. M

    Superradiance and the assumption of indiscernable atom field coupling

    Hi, If we have a system on N atoms confined to dimensions much smaller than the wavelength corresponding to the transition, we see superradiant decay. Now, in these cases, we always assume that the excitation is symmetrically or antisymmetrically distributed. For instance, if we have one...
  45. Gliese123

    The required energy to split up an Oxygen atom

    Homework Statement "Calculate how much energy that is required for a oxygen atom 168O to split it up into 4 α-particles" The Attempt at a Solution 1: (8 * 1,00727646688)u + (8* 1,00866491578)u = 16,12753105 u The first one is the Oxygen's 8 protons and the second one is its 8 neutrons...
  46. A

    Solving system of equations to find angle and energy of Au atom and α

    Homework Statement An alpha particle traveling with a kinetic energy of 5.5 MeV and a rest-mass of 3727.8 MeV/c^2 strikes a gold atom with a rest-mass of 183,476 MeV/c^2. -The gold atom is initially at rest -The alpha particle deflects perpendicular to the horizontal in the after state...
  47. K

    Radiation Force on a Classical Atom

    Homework Statement Show that the integral under this absorption cross section,σ, from a de-tuning of -∞ to +∞ is independent of the line width of the resonance,\gamma Homework Equations I have posted an attachment with the picture of the formula. I was having some difficulties with...
  48. F

    Using recoil of atom to find correct in wavelength of emitted photon

    So firstly, the book supplies the answer of \Delta\lambda = \frac{h}{2mc} I use energy and momentum conservation. I say the total energy is that of the incoming photon, which is then changed to energy of the photon released, and kinetic energy of the atom, from the recoil. I say the same...
  49. K

    The dirac equation of the hydrogen atom

    What potential would one use when evaluating the Dirac equation of the hydrogen atom? Would it simply be in the form used when examining the hydrogen atom-Schrodinger equation or does it need modification?
  50. jaumzaum

    A lot of considerations about the Bohr's Hydrogen Atom

    I'm studying the Bohr's hydrogen atom and my teacher gave us a challenge question. When I was working in the problem I've got a couple of other questions that I don't know the answer. The initial problem was the following: Today we know the electrons are not the only particles moving inside...
Back
Top