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. F

    Bose Einstein condensate/ atom laser

    Dear, I am reading a paper on Bose Einstein condensate and an atom laser. I have two questions which are bothering me for a time. - When you are going to make do all the atoms start with the same the Broglie wavelenghts or do they start with different wavelenghts due to different...
  2. A

    Electrical activity of an atom

    the electrical activity of an atom is the same electricity of a light bulb?
  3. fluidistic

    Using Hund's rule, find the fundamental term of an atom

    Homework Statement Using Hund's rule, find the fundamental term of an atom whose last incomplete subshell contains 3 electrons d. Do the same with 4 electrons p. Homework Equations The 3 Hund's rules. The Attempt at a Solution By fundamental term I'm guessing they mean the...
  4. S

    Number of atoms trapped in an atom trap

    Homework Statement a group of atoms are confined in a point like volume in a laser based atom trap, the laser light causes each atom to emit 1.0 x 10^6 photons of wavelength 780 nm every second. the sensor has area of 1 cubic centimeter and measure the light intensity emanating from the trap...
  5. A

    Can an Antiproton Replace an Electron in a Heavy Atom and Create a Stable Atom?

    Is it possible to replace one of the electrons in a heavy atom like uranium with an Antiproton and form a stable atom?
  6. S

    How spinor vector envolves in describing the atom

    how spinor vector envolves in describing the atom
  7. E

    Question about Quantum Theory regarding hydrogen atom and photon

    Assume the universe consists of a single photon, a single atom of hydrogen and a spherical detector (like an encompassing shell) with a semi-infinite radius. The photon gets "absorbed" by the hydrogen atom. Moments after the photon is emitted. My question is the following: from the time...
  8. O

    How to calculate the surface atom density of an fcc(111) surface?

    How do you calculate the surface atom density of an fcc(111) surface expressed in terms of a? I've managed to do it for fcc(100) and fcc(110), but I can't seem to figure it out for fcc(111). Any help would be greatly appreciated!
  9. C

    Bohr Model of Atom: Stability Condition Explained

    Eisberg and Resnick says that the condition for stability of the atom is: k Ze2/r2=mv2/r What I fail to understand is why the Z isn't square too. I mean surely you have Z electrons interacting with Z protons which which would surely give q1q2=(Ze)(-Ze)=-Z2e2? What am I missing?
  10. Y

    Is whole Carbon 13 atom (not just the nucleus) a fermion or boson?

    This ought to be simple, I think. But I haven't found a consistent way to think about things yet. Is it as simple as adding up all the spins of the elementary particles in the particle and checking whether the total has inter or half-integer spin? Homework Statement State whether the...
  11. J

    Magnetic interactions of atom

    as far as i know it takes certain amount of energy for an electron to change orbit now what i am wondering is why the energy required for an electron to change orbit doesn't change when close to let's say another positively(or)negatively charged atom thank you for your time and sorry for the...
  12. R

    Is it possible to have a single photon ionize an atom of Francium?

    Is the ionization energy of Francium to high to be achieved with just one photon? And another quick question, how hot must the light-emitter get before it begins to emit x-rays, and then how hot for gamma rays?
  13. E

    Why can't an electron have a even lower energy level in atom?

    Why can't an electron have a even lower energy level in atom and be closer to the nuclei? (as the next step is to fuse with one of the protons and make neutron.. )
  14. M

    Why atom shells can only hold specific numbers of electrons

    I am looking for a fairly simplistic answer to why different "shells" in atoms can only hold a specific number of electrons. There is so much based on valence electrons and how many electrons make a full shell but, do we know why atoms "seek" a full outer shell? It seems like there should be a...
  15. N

    Time Scale of Atom: Understanding EM-Beam Coherent Force

    Hi I am reading about the force of a coherent EM-beam acting upon an atom, and I have a question in this regard. It is regarding the explanation on page 150 of this book, starting from "The geometric approximation of atom optics is valid when"...
  16. J

    Derivation of formula for orbital ranges in hydrogen atom

    I almost have the answer, I'm sure there's just a minor flaw in my reasoning. Here it goes: We're given that the angular momentum of the atom is integer multiples of h-bar (n\hbar) (integer depending on the orbit). Now the centripetal force is given by F = \frac{mv^2}{r} = \frac{p^2}{mr} =...
  17. N

    Understanding Force on an Atom in the Heisenberg Picture of Quantum Mechanics

    Hi In the following paper (on page 5) is the standard derivation of the force acting on an atom, whose center-of-mass motion is described classically. What I don't understand is the step taken from (5) to (6). The QM-version of the force is defined using Heisenbergs Equation of Motion (so...
  18. D

    What actually happens when a photon strikes an atom?

    I know that when a photon strikes an atom, it excites an electron, which then will re-emit the photon when it returns to normal. But what is actually happening here? Is it really as simple as that, or is there something more fundamental going on here, like how nuclei are bound together using...
  19. E

    If an Atom was the size of a grain of salt

    What object would represent the size of a grain of salt at this scale? Would it be bigger than Earth?
  20. J

    Hydrogwn atom electron probability

    Ok i don't know anything about quantum physsics but when i was reading about it( for the sake of learning new stuff) i had this question :- Does the attraction between protons and electron play a role in determining where the electron probability is maximum at? I was seeing the graph of...
  21. J

    What are the energy states of a hydrogen atom in a B field?

    If a a 1s hydrogen atom is placed in a B field, how many energy states will it split into?
  22. J

    Stability of the atom in QFT

    If I may, I would like to give this question another try, especially if guys with some cabala in QFT can address it. Is it possible to show in the relativistic quantum theory, that the hydrogen atom is stable? (Electron will not fall onto the proton)? I explain. In the non-relativistic...
  23. facenian

    Radial wave function in H atom

    helo can someone tell me where I can find detailed explanation about normalization and orthogonal properties of the radial functions since the books I've been reading do not explain enough, I thought Laguerre associated polynomials resolved the problem directly but this is not the case, the...
  24. Q

    Hypothetical atom + Rydberg equation

    Homework Statement Consider the following energy levels of a hypothetical atom. E4 -1.0 10-19 J E3 -5.0 10-19 J E2 -10 10-19 J E1 -15 10-19 J (a) What is the wavelength of the photon needed to excite an electron from E1 to E4...
  25. M

    Why do atomic radii increase as you move down a column in the periodic table?

    About the atomic radius, as a starter it was mentioned (and correct me if am wrong) that: Rcation < Ratom< Ranion (And we'll know the size of the atom based on these) Then it was mentioned that: Radius of atom of a certain element increase if we walk straight downwards along a column in the...
  26. A

    If an atom was scaled up to the size of a sports oval with a diameter of 150m ?

    How big would the nucleus be? A grain of sand (0.1cm diameter) A marble (1cm diameter) It's a grain of sand right(?); since the relationship between the diameter of an atom and its nucleus is 100,000 to 1. 150/0.001= 150,000
  27. M

    Density of State for a two atom basis

    Homework Statement I have a problem on my assignment in which I am required to find the specific heat of a two atom basis (diatomic) using the Debye model. My problem is coming up with the density of states for a diatomic setup in 1D. Homework Equations Density of state...
  28. B

    Exploring the LJ Cohesive Energy of a 4 Atom Square

    Homework Statement i) Write down an expression for the LJ cohesive energy of a molecule consisting of four atoms lying on the corners of a square of side a. ii) Deduce the equilibrium value of the nearest-neighbour separation, a, assuming the molecule retains its square shape iii) What...
  29. C

    Niobium atom lattice structure and its behavior

    Hi, I am trying to understand how do cluster of niobium atoms behave when I apply force to compress/stretch them. Niobium has a cubic lattice structure, 8 atoms on each corner and 1 in the center. So my question is let's say I have 2 of these cubes connected, and composed of 14 atoms. In...
  30. V

    Understanding Spherical Symmetry in the Hydrogen Atom

    Hi everyone! So we're learning about the Hydrogen atom in QM and I'm having trouble reconciling something in my head. We're looking at potentials that are only radius dependent, like the Coulomb potential. Now, I know the math. I see that we assume the wave function can be separated into the...
  31. L

    Atom Density in Silicon (100), (110), and (111) Planes

    Homework Statement For the (100), (110), and (111) planes of a Silicon crystal sketch the placement of atoms on the plane and determine the atom density (atoms/cm^2) on the plane. Homework Equations As of now I think the only relavent equation would be the atom density which is...
  32. V

    Hydrogen Atom Energy: Ratio of νBohr/νorbit

    Homework Statement In Bohr’s hydrogen atom, the frequency of radiation for transitions between adjacent orbits is νBohr = (En+1−En)/h. Classically, a charged particle moving in a circular orbit radiates at the frequency of the motion, νorbit = v/2πr. Find the ratio νBohr/νorbit for the...
  33. P

    Hydrogen like atom, perturbation theory

    Hi all ! I need some help Homework Statement The nucleus of an hydrogen-like atom is usually treated as a point charge Ze. Using the first order perturbation theory, estimate the error due to this approximation assuming that the nucleus is a sphere of radius R with a uniform charge...
  34. S

    Energy of an electron in a uranium atom

    using special relativity m = m0/(1-v^2/c^2) on an electron orbiting with a speed of 2.01 * 10^8 m/s in an atom,estimate the percentage corrections to the n=1 energy in a uranium (Z=92) atom. so to find the energy I first need the reduced mass, u, for En = u*(9e9)^2*e^4*Z^2/2(h bar)^2*n^2. How...
  35. A

    The Orbital of Nitrogen atom in Ammonia

    Homework Statement Experimental evidence suggests that the nitrogen atom in ammonia, NH3 , has four orbitals in the shape of a pyramid or tetrahedron. Draw an energy-level diagram to show the formation of these orbitals. (Hint: No electron promotion is required.) Homework Equations...
  36. J

    Probing the atom with light high velocity particles

    Homework Statement The first part asks to find the necessary momentum of a "relativistic projectile particle" in order to resolve a diameter of 10^-10m (i.e. the atom). The second part asks to find the corresponding energy of the projectile particle, in GeV. Homework Equations λ = h/p E2 =...
  37. binbagsss

    Quick Uncertainty Problem - atom energy levels

    Two quick problems, not sure whether the 2 are related or not: 1) The question is: A sodium atom in one of the states laveled 'lowest excited lvels' remains in that state, on average, for 1.6 x 10^-8 s before it makes a transition to the ground level, emitting a photon with wavelength...
  38. T

    What is the Temperature of an atom moving at the speed of light?

    What is the Temperature of an atom moving at the speed of light? Since absolute zero is the lack of activity and energy and since no physical object can move faster than the speed of light What is the temperature of an atom moving at the speed of light? Light is either a particle...
  39. J

    Trivia: Potential of the hydrogen atom

    When (what year and by whom?) was it discovered that the hydrogen potential is V=-1/r ? I imagine this was deduced from experimental data... amirite? Quite urgent... From wiki it looks like it was found in teh 1920's but I'm not certain so I just want to check. Thanks in advance
  40. S

    The Hydrogen Atom Ground State: Radiation Emission

    when proton and electron combine to form hydrogen atom(ground state) what is the source of radiation emitted
  41. Y

    Probabilty of finding the electron of the hydrogen atom in

    Homework Statement The average function of the H-atom in its ground state is ψ(\vec{r})=(1/(πa03)1/2exp(-r/a0) a0: Bohr radius a.What is the probability i. P(\vec{r})d3\vec{r} that the electron will be found in the volume d3\vec{r} around \vec{r}? ii. Pdr that the electron will be found...
  42. F

    Solve Bohr Atom Problem: Find Radius, Energy, Wavelenght

    Find the first radius, the energy of "connection" and the wavelenght of the first risk of Lyman series of a hydrogen atom that electron has been "replaced" for a meson with negative charge with a mass 207*electron mass. Radius: r = (h^2*n^2)/(4pi^2*e^2*k*me) we know all constants so we just...
  43. L

    Expectation Values of Radii in the Hydrogen Atom

    Homework Statement Determine for the hydrogen atom states 1s and 2p the expectation value of the radius r and the associated mean square error Δr. Homework Equations Wave Functions for 1s and 2p from Demtroeder's Experimental Physics Volume 3 (it says "The normalized complete...
  44. T

    Angular momentum and the hydrogenic atom

    This is a problem that's been bothering me for a while. For electrons "in" hydrogenic atoms, do the electrons in states for which l=0 actually orbit the nucleus, or would they only ever be observed to be moving radially (assuming they could be directly observed in that way). Here's my logic...
  45. C

    Is ZPE of an electron in an atom obtained intrinsically or extrinsically

    There are two cases I could think of: Case 1: The electron is constantly in a state of unrest due to the hiesenburg uncertainty principle, and the ZPE of that electron is caused from the state of its own unrest. Case 2: The electron is constantly in a state of unrest becuase it is...
  46. T

    Ground State Energy of Helium Atom - Integration problem

    I'm trying to follow a derivation of the ground state energy of Helium using perturbation theory. I've made it through most of the derivation but I'm stuck at the following integral Homework Statement Find the value of C where C=\frac{1}{(4\pi)^2}\int...
  47. T

    Why is it impossible to change the number of protons of an atom?

    Why is it impossible to change the number of protons of an atom? Is it because the protons are in the nucleus? How can we change the number of neutrons then?
  48. D

    Can the size of an atom change?

    I've been searching and trying to find an answer to this. I'm not scholar or physics major. I'm asking for some guidance about this subject. The big bang theory, leaves me with the impression that atoms can change size. Is this true? Can gravitational forces compress, can atoms...
  49. H

    Ionization energy of lithium atom

    Homework Statement Estimate the ionization energy of Lithium. Neglect the repulsion between the electrons. Homework Equations what is the equation that can be used here? There are thousands of tables in the web having tabulated the values of various ionaziation energies. But one can hardly...
  50. S

    Two hydrogen atom with same spin can form H_2?

    As I know from the laws of chemistry,to form H_2 the H atoms must have opposite spin. What if they have the same spin? I mean, can an H atom rotate to swap his spin (i'm not expert of the dynamics of spin), or there is no way to couple them? In the case I have a gas of H with all of them...
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