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).

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

    Spherically symmetric states in the hydrogen atom

    The equation $$\frac{\hbar^2}{2m}\frac{d^2u}{dr^2}-\frac{Ze^2}{r}u=Eu$$ gives the schrodinger equation for the spherically symmetric functions ##u=r\psi## for a hydrogen-like atom. In this equation, substitute an assumed solution of the form ##u(r)=(Ar+Br^2)e^{-br}## and hence find the values...
  2. T

    I Atom in a Decayed / Non-Decayed State

    In Sheldon Glashow's critical review of "What is Real? The Unfinished Quest for the Meaning of Quantum Physics" by Adam Becker, there is one paragraph I don't understand. In Glashow's thought experiment of a single radioactive atom in a box: My thought experiment is like Schrödinger’s, but...
  3. E

    A Feynman solution for the radial wave function of the hydrogen atom

    Reading the classical Feynman lectures, I encounter the formula(19.53) that gives the radial component of the wave function: $$ F_{n,l}(\rho)=\frac{e^{-\alpha\rho}}{\rho}\sum_{k=l+1}^n a_k \rho^k $$ that, for ##n=l+1## becomes $$ F_{n,l}=\frac{e^{-\rho/n}}{\rho}a_n\rho^n $$ To find ##a_n## I...
  4. L

    I Hydrogen atom: Energies and eigenstates

    When we say energy levels of the hydrogen atom. Are that energies of the atom or of an electron in the atom? Also corresponding states? http://hyperphysics.phy-astr.gsu.edu/hbase/quantum/hydwf.html Why energies are negative? E_n \propto \frac{-1}{n^2}
  5. Muthumanimaran

    B How trapped ions can be used to make Atomic clocks?

    Can someone explain me conceptually how one can use trapped ions to make atomic clocks? My basic understanding of trapped ions is, we can think of an ionized atom which is controlled by electric and magnetic fields. But i am wondering how can one build an atomic clock using trapped ions.
  6. J

    I Is the electric field of an atom a superposition or mean of electron positions?

    We usually think about atomic orbital as wave(function), but it was created from e.g. electron and proton approaching ~10^-10m (or much more for Rydberg atoms), and electron has associated electric field. This wavefunction also describes probability distribution for finding electron (confirmed...
  7. thaiqi

    I Exploring Dynamics of Electron in Hydrogen Atom

    Hello,everyone. Can dynamical system be used to describe the behavior of the electron in Hydrogen atom?
  8. Buzz Bloom

    I Q re a photon ionizing a hydrogen atom

    This question is a followup to another thread. https://www.physicsforums.com/threads/qs-re-the-behavior-of-atoms-after-decoupling-completed.994581/ I would like to explore the issue raised by @kimbyd. . . . after reionization the temperature of the intergalactic medium is dominated by...
  9. omegax241

    A strange wave function of the Hydrogen atom

    I am trying to solve the following exercise. In a H atom the electron is in the state described by the wave function in spherical coordinates: \psi (r, \theta, \phi) = e^{i \phi}e^{-(r/a)^2(1- \mu\ cos^2\ \theta)} With a and \mu positive real parameters. Tell what are the possible values...
  10. LCSphysicist

    Schrodinger equation in three dimensions. Atom with one electron.

    When solving the Schrodinger equation by separation of variables to atom with one electron and in the spherical coordinates, we get $$\Psi = \Theta(\theta)\phi(\varphi)R(r)$$ Specifically, $$\phi = e^{im\rho }$$ The question is, why we adopt this particular solution, in general, we have this...
  11. jjson775

    Normalization of the wave function for the electron in a hydrogen atom

  12. E

    B How can an atom have a negative charge?

    I have a neutral charged atom. When I bring an electron to this atom what the force will hold this electron with neutral atom?
  13. M

    I What is the effect of a magnetic field on an atom's magnetic moment?

    Hello! I want to make sure I understand (mainly qualitatively) what happens to an atom in a magnetic field. Assume we have an atom with an even number of protons and electrons. This means that all proton (electrons) are paired up, except for one of them (I am not totally sure if this pairing is...
  14. Tony Hau

    Why is the Electric Field of a Polarized Atom Different in Textbooks?

    The question is like this: The solution is like this: However, according to the equation for ##E_{dip}## , what I think is that it should be: $$E=\frac {1}{4 \pi \epsilon_o} \frac {qd}{d^3} \hat {\mathbf z} $$, where I take the centre of the sphere in figure 2 as the centre of the...
  15. Helios

    B Did Georges Lemaître Think the Universe Began from a Point?

    [ Wikipedia quote ] Georges Lemaître first noted in 1927 that an expanding universe could be traced back in time to an originating single point, which he called the "primeval atom". Exactly what did Georges Lemaître do? What did he suppose? What did he solve? Did Lemaître think the universe...
  16. P

    Finding the excess electrons per lead atom

    a. This is easy with ## q = n*e ## ## 3.2 * 10^{-9} = n * 1.6*10^{-19} ## ## n = 2*10^{10} ## electrons b. Total Lead atoms are ## \frac {8 * 6.022*10^{23}} {207} = 2.3 *10^{22} ## I used the Avogadro number. Total electrons = ## 2.3 * 10^{22} * 82 = 1.88 * 10^{20} ##, here i multiplied with...
  17. AndreasC

    Help with 3-D interactive QM visualisation of a hydrogen atom

    First of all, I got to decide what I'm going to use to make the simulation. I know Fortran, Matlab etc but I'm pretty sure these won't help me much. I learned some C++ a couple years ago but my knowledge is rusty, however I think I'm going to use that combined with Unreal Engine, since it makes...
  18. CuriousS

    B What occurs when electrons stop orbiting the nucleus?

    What will happen if somehow we make electron to stop revolving around the necleus?
  19. S

    I Breaking an atom down in it's components.

    Good day, I have a question about breaking an atom down in it's components. For an example we have a neutral 4-helium atom. The helium atom have a nucleus which contains 2 protons and 2 neutrons. Around the nucleus of the helium atom 2 electron orbits in the k-shell (according to Bohr's...
  20. A

    B Area of a Circle in an Electron's Hydrogen Atom

    My textbook says "A is the area of the circle enclosed by the current" (produced by an electron in a hydrogen atom), A = ##\pi r^2 \sin(\theta)^2##. I don't understand where the ##\sin(\theta)^2## comes from.
  21. K

    TISE solution for a hydrogen atom

    I am unable to complete the first part of the question. After I plug in the function for psi into the differential equation I am stuck: $$\frac {d \psi (r)}{dr} = -\frac 1 a_0 \psi (r), \frac d{dr} \biggl(r^2 \frac {d\psi (r)}{dr} \biggr) = -\frac 1 {a_0}\frac d {dr} \bigl[r^2 \psi(r) \bigr] =...
  22. N

    Torque on an atom due to two infinite lines of charge

    Hope someone can help!
  23. F

    Bohr Model - Absorbing a Photon with Enough Energy to Ionize the Atom

    I just want to confirm something. You need about 13.6 eV of energy to ionize a hydrogen atom in the ground state. Can the atom absorb a photon with 15 eV of energy? I think it can. This would free the electron, and the freed electron would move off with a kinetic energy of 15 minus 13.6 eV...
  24. cemtu

    Quantum Mechanics Hydrogen Atom Expectation Value Problem

    I can not solve this problem: However, I have a similar problem with proper solution: Can you please guide me to solve my question? I am not being able to relate Y R (from first question) and U (from second question), and solve the question at the top above...
  25. cemtu

    Quantum Mechanics hydrogen atom eigenfunction problem

    This is a general property of eigenvectors of Hermitian operators. State functions are a particular class of vector, and it is easiest to work in the general formalism (I am hoping to show how ket notation makes qm easier, not just do standard bookwork at this level). Suppose O is a Hermitian...
  26. bob012345

    I Lithium Atom Ground State Radial Wavefunction

    I would like to see what the shape of the ground state radial wavefunction for the Lithium atom is. An approximate function that shows the shape would be fine. Thanks.
  27. J

    Spectral lines from electron energy transitions in this atom

    Do they mean something like this?
  28. B

    Radius of the electron orbit in a Hydrogen atom

    I am really stuck on what to do here in this question I have arrived at forming an equation to work out the radius of electron orbit from doing the following However I do not know what to do next as I don't know what the value of n (quantum number) must be? :oldconfused: Any help would be...
  29. L

    I Is the potential energy always negative in the ground state of a hydrogen atom?

    Why energy of the electron in ground state of hydrogen atom is negative ##E_1=-13,6 \rm{eV}##? I am confused because energy is sum of kinetic and potential energy. Kinetic energy is always positive. How do you know that potential energy is negative in this problem?
  30. S

    Solving Bohr Atom Problem (Qs a-e)

    Hello folks, I've managed questions (a) and (b) but don't get what to do with part (c). Normally you would equate the velocity equations v2=e2/4πεmr=(n2h2)/(m2r2 ). This let's you isolate the radius and use it to calculate En. But I can't see how you could do this for v given in (a) and (b)...
  31. U

    I Will thermal disturbance change an atom's spin?

    If thermal motion (collision of atoms) changes the direction of an atom, will that change the direction of spin? If so, how much time does it take from the change in the atom orientation to the change in the spin?
  32. C

    B States of Matter - particles or atoms?

    Resources I have looked at distinguish between the three basic states of matter in terms of how closely particles are held together; i.e. in solids they are bound most closely, in liquids less so and in gases they're much freer. Would it not be more correct to refer to how closely atoms or...
  33. Frigus

    B Quantum mechanical model of an atom

    We say that principal quantum number tells us the average distance from the nucleus, so the sub shells of some principal quantum number say 3 has 3 sub Shells 0,1,2 and in 3p sub shell their will probability of finding the electron near the nucleus which doesn't mean electron will find in region...
  34. A

    I Less binding energy, increased atom energy?

    I'm a bit confused as to what is meant by Professor Simon in is textbook Oxforc Solid State Basics. I attached a photo of the page (number 213). Here is my confusion: "In this case, the electrons see the full charge of the nucleus and bind more strongly, thus lowering their energies." Binding...
  35. T

    B Can Hydrogen Atoms on Earth and the Moon Share Electrons?

    Is it possible to find a hydrogen atom which atomic nucleus is on Earth and electron is on moon?
  36. F

    I What happens if a low energy photon collides with an atom in the ground state?

    What happen if a small energy photon collide an atom in ground state that the gap between energy levels of atom is greater than energy of photon?It seems that the medium absorbs light and transform to heat?
  37. A

    Carbon atom larger than a water molecule? Measuring a molecule's size?

    So there's a website here: https://learn.genetics.utah.edu/content/cells/scale/ That shows the scale of various entities (coffee bean, viruses, a carbon atom, a water molecule etc). It says that the carbon atom is larger than the water molecule. This is based on the 'van der waal radius'...
  38. F

    I Why does the energy level of an electron in an atom have a width?

    Electron in atom at higher level(excited state) of energy has tendency jump to lower level of energy.Then the state of electron is unstale,so there is uncertainty in energy of the electron(the level of energy has a width).What cause the level being a band of energy but not a thin line of...
  39. N

    Spin Hamiltonian of a hydrogen atom in a magnetic field

    qa
  40. olgerm

    I Wave function for a helium atom

    Can you say whether I understood these things correctly? to get condition on wavefunction ##\Psi## for a system that consists of 2 electrons(without taking spin into account) and helium nuclei I can solve schrödinger equation: ##i*\frac{\partial \Psi}{\partial...
  41. B

    Electric field of light emitted by atom, given the intensity

    For t < 0 , all I can think of is a qualatative " the field is zero because the intensitity is 0 when the burst of light hasn't been emitted yet " For t >= 0 , I've tried squaring the given E and that let's me say the amplitudes are proportional (with a cos^2 term in the mix) But I feel like...
  42. F

    Can a photon with energy greater than energy level difference of atom.

    Can a photon with energy greater than energy level difference of atom be absorbed by atom?Is there any case in that photon share a part of energy for atom and keep other part of energy for itself?
  43. S

    Overcoming Nuclear Forces: A Look Into the Physics of the Atom

    Is it that work is done to overcome the nuclear forces holding the nucleus together?
  44. T

    I Electric dipole moment of the nucleus of an atom

    Summary: Why is the electric dipole moment of the nucleus of an atom equal zero? Summary: Why is the electric dipole moment of the nucleus of an atom equal zero? I read about the hyperfine interactions that cause the altering of the energy levels of the nuclues of an atom. Under the...
  45. epotratz

    I Voltage between electron and proton in ground state hydrogen atom?

    I’m not sure if this belongs in classic or quantum physics... but here it is...Is it possible to calculate the “voltage” between an electron and a proton in a ground state hydrogen atom?I know the ionization energy is 13.6 eV, so I assume it's safe to say the voltage is 13.6 volts at a certain...
  46. M

    Calculate the energy release of an atom

    First of, I have no idea what I'm supposed to do with the neutrinos and the photons. Can somebody explain how to handle these? The rest of what I tried is quite straight forward $$\begin{align*}\Delta E &= 4M_p - M_{He} - 2 M_e + E_{\text{Neutrino and Photons}}\\&= 4M_p - (2[M_p+M_n]-E_B) - 2...
  47. Manasan3010

    Reflection of a photon by an atom

    I suppose the reason I am able to see myself in mirror and not in wood is the reflection off a mirror is specular whereas wood is diffuse. In reflective material(e.g: silver) when the photon hits the frontline atom, the atom's electrons absorbs the energy and release it back with tiny energy...
  48. SamRoss

    Is a single atom hot? Will it emit radiation?

    Trying to understand the concept of heat. As I understand it, heat is really just kinetic energy. In Newtonian mechanics, it is 1/2mv^2. Here are my questions... (1) On a microscopic level, are conduction and convection simply atoms bumping into each other and passing along some of their...
  49. Manasan3010

    I Exploring the Physics of Photoelectric Cells: Electrons, Energy & Color

    In this article, writer says that when atom is hit by photon it gets excited and expelled out of atom and this can be used to form images. My questions are: Why didn't the electrons get to a higher energy level, instead of getting knocked out? How do we find the color(frequency of wave) using...
  50. M

    I Time independent perturbation theory in atom excitation

    Hello! In Griffiths chapter on Time independent perturbation theory, he has a problem (9.20) in which he asks us to calculate the first order contribution to the electron Hamiltonian in an atom if one takes into account the magnetic dipole/electric quadrupole excitations, beside the electric...
Back
Top