Atom Definition and 999 Threads

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. N

    Exploring the Limit of Quantum Cooling in an Atom Trap

    Homework Statement Physicists use laser beams to create an "atom trap" in which atoms are confined within a spherical region of space with a diameter of about 1 mm. The scientists have been able to cool the atoms in an atom trap to a temperature of approximately 1 nK, which is extremely close...
  2. S

    Atom and Sublevels: Quantum Physics Questions Answered

    Hi, I've some doubt about quanistic physicist (aren't homework I read this stuff as an hobby) , could you help me? 1)if the electrons of a gas, for example, emit energy only when they go down level, then to get the atomic spectrum should I first give energy and then wait until electrons go...
  3. J

    Non-hermiticity of fourth power of momentum operator in L=0 state of hydrigen atom

    Non-relativistic QM. I have read in many places that the fourth power of the momentum operator (P^4) is not hermitian on the L=0 states of the Hydrigen atom. Indeed, I was able to pove this using Fnlm for the nlm state of hydrogen, computing <Fn00 | P^4 Fm00> and doing the integration by...
  4. F

    Is atom created if time is taken away from space and acceleration?

    When acceleration reach to the point of speed of light, we know that space will collapse(3D) and time will slow down(relative) does this leads to the creation of atom? Will space collapse to a single point if time is take away? I view the space(3dimension) as a sphere in which time(relative)...
  5. M

    Schrodinger's equation for H atom Some questions

    Hello, I just finished learning how to solve the Schrodinger equation for the H atom and a few things trouble me. 1) The relative particle, CoM particle treatment: From what I understand, we are solving this for the case where the nucleus is taken to have mass m1+m2 and the electron has mass...
  6. D

    What Are the Final |L,S> States After Ground State Pionic Atom Decays?

    Homework Statement A pion is a spin-0 particle with a negative unit charge. A neutron is a spin-1/2 particle with no charge. A proton is a spin-1/2 particle with positive unit charge. One can construct an unstable version of the hydrogen atom where the nucleus contains both a proton and a...
  7. B

    Internal magnetic field experienced by H atom Electron

    Homework Statement A 21 cm spectral line corresponds to the flipping of the electron in a hydrogen atom from having its spin parallel to the spin of the proton to having it anti-parallel. Find the internal magnetic field experienced by the electron in the hydrogen atom. Homework Equations...
  8. B

    Bohr's Model of the Atom: Correct Answers from an Incorrect Hypothesis?

    Homework Statement In the Bohr atom, electrons move on classical circular orbits that have angular momenta lh/2pi, where l = 1, 2, . . .. Show that the radius of the first Bohr orbit is a0 and that the model predicts the correct energy spectrum. In fact the ground state of hydrogen...
  9. A

    Dynamics of electron in Bohr Hydrogen atom

    1. Consider Bohr Hydrogen atom with counter-clockwise electron orbit in the xy plane with intial position r(0)=-a0y. The angular frequency of the orbit is w. Derive an expression for the position of electron at a later time t, r(t) in terms of a0 , w, t, x, and y. Homework Equations...
  10. M

    How many neutrons there should be to keep an atom stable

    (1) Is there any equation to determine how many neutrons there should be to keep an atom stable? I don't mean mass - number of protons. I mean the equation that can determine an interval of neutrons based on atomic number only and the forces. (2)Why can't there be an hydrogen atom with 6...
  11. A

    Real Hydrogen Atom: Exploring Electron Energy Effects

    I've heard that the hydrogen atom that we originally learn about in QM that deals with the Coulomb force is an incomplete description. I'm having trouble understanding all of these effects. When describing the electron energy of the real Hydrogen atom, how do things like the zeeman effect...
  12. C

    Hydrogen atom with discrete nonlinear Schrödinger equation

    Hi everyone, How can I solve hydrogen atom with discrete nonlinear schrödinger equation? Could you help me with the mathematics of that, please?
  13. H

    For what Z values does an atom begin to differ from a nonrelativistic model?

    Homework Statement "Relativistic effects are rather small in the hydrogen atom, but not so in higher-Z atoms. Estimate at what value of Z relativistic effects might alter energies by about a percent and whether it applies equally to all orbiting electrons or to some more than others. For this...
  14. M

    Why Does the Charge of a Lead Nucleus Affect Electric Field Calculation?

    Homework Statement The nucleus of a lead atom has a charge of 82 protons a. what are the direction and magnitude of the electric field at 1.0x10^-10 m from the nucleus? Homework Equations E=Kq/r^2The Attempt at a Solution I did E= ((9 x10^9)(1.6X10^-19)^82)/ (1.0x10^-10)^2 but when I...
  15. D

    <r> and <V(r)> in the Hydrogen Atom.

    Hi. I'm a 3rd year undergraduate studying Applied Physics and I'm having some trouble with a problem concerning the Hydrogen Atom. This is my first post so please forgive the sloppy equations. Not really used to writing this stuff out without an equation editor handy! Anyway, the...
  16. A

    Atom composition (simple question but hard for me)

    Homework Statement Fe3(Co)x, Fe is 33.26% by mass. Find the value of x. The Attempt at a Solution 167.5425 g / 0.3326 = x ( 58.9326 g) / 0.6628 x = 5.6... but the right answer given was x=12. question...
  17. T

    Can an Electron Absorb a Photon Without Making a Complete Energy Level Jump?

    Hi! Today we discussed atomic physics in our class, and the following question came up: Consider an atom, and consider for example its three lowest energy states. Suppose these correspong to the energies E1,E2 and E3, respectively. Will it be possible for an electron in the lowest energy state...
  18. H

    Wavefunction solution to the Schrödinger Wave Equation for a H atom

    On my notes, the lecturer left out some of the formulae as blanks which we were supposed to fill in as we went a long but I'm missing a few of them. The 1st one is: [PLAIN]http://img213.imageshack.us/img213/6627/screenshotdh.png I'm stuck here, I can't figure out what equation he's...
  19. M

    Primordial Black Hole as nucleus for gravitic atom

    I'd like to consider a primordial black hole in the absence of Hawking radiation. When you consider the case of a primordial black hole with a Schwarzschild radius on the same order as the radius of a proton, I calculate its mass to be at around 6.75x10^11 Kg. If I then calculate the...
  20. R

    Spin orbit coupling for atom at centre of complex

    Hello Forum, This is my first post. There is some preamble, but the problem itself is straightforward enough, even though I cannot solve it. I'm trying to calculate the spin orbit matrix for an alkali metal atom at the centre of a complex of 12 noble gas...
  21. D

    Root mean square speed of helium atom

    Homework Statement Helium is used to fill a balloon of diameter 44 cm at 22 degrees C and 0.9 atm. The mass of a helium atom is 4.0026 u, the conversion factor from u to kg is 1.66 x 10^-27 kg/u, the conversion factor from atm to Pa is 1.013 X 10^5 Pa/atm, the universal gas constant is...
  22. Z

    Neutron colliding with an atom

    Homework Statement A neutron moving with a speed v makes a head-on collision with a hydrogen atom in ground state kept at rest. Find the minimum kinetic energy of the neutron, for which inelastic collision may take place. Mass of neutron = Mass of Hydrogen = 1.67 x 10-27kgThe Attempt at a...
  23. T

    Calculating Atom Density of UO2-ThO2 Fuel

    if fuel coposition as follow : 75 wt% Tho2- 25 wt% uo2, were the U enrichment 19.5 w% ... how can i caculate the number density (Atoms/barn-cm) for the comopsition ?
  24. H

    Splitting H atom = High energy?

    Hydrogen Fusion = High energy? Where does the energy come from when a Hydrogen atom is fused? Is the energy stored in some part (proton, neutron, electron)? Thank you if someone can give me some idea about this. I guess it is about the strong nuclear force, but I'd like to know in a bit more...
  25. W

    Shaking the Atom: Electron Shells & Nucleus Resonance

    The nucleus has positive charge, with negative electron shell(s) around it. The nucleus is located in the center of the electron shell. Electrical forces keep it there. Now what if we shine electromagnetic radiation (linearly polarised) onto an atom? With the E-field going "up", will the...
  26. A

    Hydrogen atom (HELP ME FAST PLEASE)

    Hi, I'm trying to figure out the solution for the ground state of the hydrogen-atom, however it is not going well. As far as i know, you can supress the angular dependence, because the states of hydrogen (or at least some of them) are spherically harmonic. This way the schr. equation just...
  27. T

    What determines the number of electrons in an atom

    Say for example we consider Helium. It has 2 neutrons and 2 protons. Based on this, and using Schodingers equation we can calculate the energy states of the various orbitals of Helium (using self consistent field approach or by completely solving the Schodingers equation using finite...
  28. Demon117

    Coulombic interaction between the proton and electron of a hydrogen atom

    In the position representation, its true that we can use operators to represent the coulombic interaction between the proton and electron of a Hydrogen atom. I've never actually given any thought as to what the elements of such an operator would be (in matrix form of course). I know these...
  29. Z

    News Why is Atom Bomb limited to certain countries?

    Why can't every country make an 'Atom Bomb' ? Everyone knows that we require a fissionable material and an explosive. What else is required that is to be invented (rather discovered) by other countries? All comments are welcome.
  30. Peeter

    Hydrogen atom. state after L_z measurement

    Homework Statement An initial state is given: {\lvert {\psi(0)} \rangle} = \frac{1}{{\sqrt{3}}} \left( {\lvert {100} \rangle} + {\lvert {210} \rangle} + {\lvert {211} \rangle}\right) An L_z measurement is performed with outcome 0 at time t_0. What is the appropriate form for the ket...
  31. R

    Collision between alpha particle and helium atom

    Why their tracks after collision has an angle 90 degree? Any detail derive?
  32. 3

    Do Atoms Need Fuel? A Curious Question

    Do atoms require fuel or does the electron move about the nucleous in the some way the Earth rotates the sun? Maybe it's a stupid question but I've always wondered about this.
  33. S

    Calculating Rydberg Values & Muonic Atom Radii

    PLS Help me ! Homework Statement 1)What is the ratio of the Rydberg value for doubly ionized lithium, a one electron atom with a nucleus of charge Z=+3e, to that of hydrogen ? Include reduced mass effects in your calculations. 2)The muon, with mass 209 m(electron) acts as a heavy...
  34. M

    How to Calculate Force of Atoms Using the Yukawa-Type Potential Energy Function?

    The Yukawa-type potential energy function for the interaction of a particular pair of neutrons in an atomic nucleus is U(r) = -(a/r)U(sub o) (e^(-r/a)) where U(sub o) = 5 x 10^(-12) J and a = 1.5 x10^(-15) m. Find the force as a function of r, then evaluate the force for r=a and r=3a. To get...
  35. T

    Number of electron of a Hydrogen atom (molecule)

    Hi, If the normalized 1D wave-function of hydrogen atom for n=1, l=0, m_l=0; \psi_{1s}(x)=\frac{1}{\sqrt{\pi} a_{0}^{3/2}}e^{-x/a_{0}} and probability distribution of wave-function, \mid\psi_{1s}(x)^2\mid so integration of rho over all x should give the number of electrons which is equal to...
  36. M

    Hydrogen Atom Tables: Find Zeros of Spherical Bessel Function

    I've searched google for some decent tables but couldn't find any. I'm trying to collect Normalized Spherical Harmonics Associated Legendre Polynomials Zeros of the Spherical Bessel Function Normalized Radius Function for the Hydrogen atom etc. I'm allowed a sheet with as much of these...
  37. N

    If the universe came from a single atom, then

    If the universe came from a single atom, then... The current model says the universe came from the big bang, the original point being something as small as an atom, and this atom expanded into the size of the universe in which we see now. If this is true, then wouldn't it mean every atom in...
  38. C

    Time interval for atom collapse-rutherford model

    Homework Statement the main drawback of rutherford atomic model was that from classical E&M theory ,an electron would radiate energy and thus the radius much decrease. how do i find the time interval over which the electron reaches r=0 when starting r=2.0 x 10^-10 m ??/ Homework Equations...
  39. P

    Matrix element of Position Operator For Hydrogen Atom

    Find <nlm|(1/R)|nlm> for the hydrogen atom (nlm = 211), R is just the radial position Operator (X2 + Y2 + Z2)½.
  40. G

    Solving the Dirac Equation for the Hydrogen Atom

    Would someone tell me some website where I can find the relativistic treatment of the hydrogen atom using Dirac's Equation? I am not trying the find the method which uses Schrodinger's equation and adds as perturbations fine and hyperfine structures? Thank you. So far i have not find anything...
  41. A

    The Hydrogen Atom (Schrodinger vs original Bohr theory)

    What quantities appear in both the Schrodinger approach and the original Bohr theory of a hydrogen atom? Also, in what ways do the two approaches differ? I'm not sure which quantities appear in both approaches. My guess would be that it has something to do with the energy levels and angular...
  42. H

    Atom of Neutrons: Can We Make It?

    Can we or have we made an atom of neutrons?
  43. M

    Hartree-Fock on a single Oxygen atom

    I'm using the TURBOMOLE program to do some basic HF calculations. They all went fine except for the single oxygen atom. After doing an extended huckel theory guess to begin with, it recommended these occupations (d2h symmetry). That looks fine to me. The top two orbitals (4 and 5) are singly...
  44. W

    Finding the Radius of a Thomson Atom in Relation to Hydrogen Atom Radius

    Homework Statement Assume that the density of positive charge in any Thomson atom is the same as for the hydrogen atom. find the radius R of a Thomson atom of atomic number Z in terms of the radius Rh of the hydrogen atom. Homework Equations The Attempt at a Solution I don't...
  45. B

    Coupling of angular momenta of many-electron atom

    There are two cases introduced in the lecture notes, depending on strength of spin-orbital coupling in individual electrons, since V_{SL} \propto Z^{4}. 1) jj coupling, which is valid for large-Z atoms, where spin-orbital coupling > electrostatic replusion between electrons 2) L-S coupling or...
  46. M

    Lowest Energy State of Hydrogen Atom: Find A, Don't Miss the Obvious!

    A hydrogen atom is in the state \psi=Ar^2e^{-r/a}cos(\theta). I need to find lowest energy state and etc. Obviously normalize to find A, but I'm not seeing the obvious linear combination of wave functions; and I really don't think my instructor wants me to do several inner products (plus...
  47. T

    Hybridization of Carbon in a Triple Bond: Explained

    Homework Statement What type of hybridization occurs in the orbitals of a carbon atom participating in a triple bond with another carbon atom? The Attempt at a Solution I honestly thought it would be sp3 but it turns out to be sp. Can someone explain this to me? Thanks!
  48. D

    Solving the Mystery of Hydrogen Atom Ionization

    Here comes a pretty hard question, which not even my QM teacher has been able to answer. When we think about one hydrogen atom, and put it in an electric field along the z-axis \bar E = \bar e_z E. Then the potential for a hydrogen atom will look like this: U = -\frac{e^2}{4\pi \epsilon_0...
  49. H

    Proving the Visible Emissions of Balmer Series in Hydrogen Atom

    Hello, I don't know if this is the right place to post.. this is a self study question from Levine, it is told that is important but i have no clue in solving it .. The Balmer series corresponds to a set of emissions involving the electron in a hydrogen atom relaxing from a high energy...
  50. fluidistic

    Calculating Probabilities for Ground State Hydrogen Atom

    Homework Statement The normalized wave-function corresponding to the ground state hydrogen atom has the form \Psi _0 = \frac{1}{\sqrt \pi} \cdot \frac{e^{-r/a_0}}{a_0 ^{3/2}} where a_0 is Bohr's radius. 1)Graph the density of probability to find the electron in a spherical edge between r and...
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