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. 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}...
  2. 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...
  3. 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...
  4. P

    Average momentum squared of Psi(100) of hydrogen atom

    Homework Statement Calculate <p2> for ψ100 of the hydrogen atom Homework Equations ψ100 = 1/(√pi) (1/a0)3/2 e-r/a0 0∫∞ r n e-B rdr = n!/Bn+1 p2 = -hbar ∇2 = -hbar2 (r2 d2/dr2 +2 r d/dr) (ψ does not depend on ø or θ) The Attempt at a Solution<p2> = ∫ψ*(p2ψ)dV ∫dV = 4pi0∫∞r2dr <p2> =...
  5. R

    How to get the volume per atom when given the unit cell size?

    1. estimate the fermi energy for lithium... the crystal structure of lithium is a bcc with a unit cell size of 3.5*10^-10 m [b]i need n, which equals N / V. if i divide by per atom, then i get (N/atom) / (V/atom) = valance / (V/atom). my question is how to get the volume per atom...
  6. S

    Hydrogen atom emitting a photon

    Homework Statement Consider the following. (a) For a hydrogen atom making a transition from the n = 4 state to the n = 3 state, determine the wavelength of the photon created in the process. (Already solved this, 1.86x10^3 nm) (b) Assuming that the atom was initially at rest...
  7. T

    Bohr Model of the Hydrogen atom: Prove that Eo = 13.6 eV

    Homework Statement Verify that the equation of the ground state energy Eo of the Bohr atom: Eo= (2pi2e4mek2)/h2 simplifies to Eo = 13.6 eV. Show clearly how the units of the different quantities in the equation simplify to the eV. This is all they give. Nothing more...
  8. Y

    Evaluating the Coulomb Integral for a two-electron atom

    Homework Statement Evaluate the so-called Direct (or Coulomb) Integral, C, which occurs in the theory of the 2-electron atom. C=\int\int d\vec{r}_1d\vec{r}_2\left|\phi_a(1)\right|^2\left|\phi_b(2)\right|^2 \frac{e^2}{\left|\vec{r}_1-\vec{r}_2\right|} You may assume that both...
  9. F

    Basic but important question on mass, matter, and atom

    Perhaps, this is an easy question, but still induces a lot of confusion to my self. I might not be the only one confused with the meaning of these concepts so it can help a ton to people, like me, confused with their meaning. So here is my confusion, Matter, as I researched it, although instead...
  10. U

    Silver Atom X-Ray Spectra: Kα & L X-Rays?

    Homework Statement For a silver atom, energy corresponding to Kα transition is 21.75 KeV. Also minimum energy of a striking electron so as to produce L X-Rays is 3.56 keV. Now, if electron with an energy of 23 keV strike a silver target the characteristic X-rays spectrum will have a)only kα...
  11. M

    Compressed/conducting Mercury(Hg) atom

    What happening with a Hg (or any other conduct metal atom) if it is compressed by an extremely strong magnetic fields from XYZ (atom at zero coordinate) and an infinite electrical current is circulating from one of axis( example ,-X and +X ) at the same time?
  12. D

    Lewis dot structure, octet rule for a central atom

    As you can see, octet rule isn't satisfied for the central atom Xe, it has 2 more electrons attached to it. So does it mean, that you should first try to make sure octet rule works for any "side" atoms, and then you just put any remaining electrons to a central atom? (or central atoms?) And if...
  13. B

    Hydrogen Atom Size and Magnetic Field Data: Understanding the Basics

    Can someone give me a link where I can find data on the size of an H atom (free and in main compounds like water)? If there is none can you tell me roughly the range of sizes or at least what is the ratio between a free atom and a bound atom. I know that for a free atom the radius is not the...
  14. M

    Possible webpage title: Understanding Nucleus Spin in Atoms

    does nucleus in an atom spin?
  15. C

    Matrix of the force on a two-level atom

    Hi, I am reading about forces on a two-level atom. In my textbook (p. 30 in Laser cooling and trapping by Metcalf & Straten) it says that the matrix expression for the force F = e\frac{\partial}{\partial z}(<\vec{E}(\vec{r},t) \cdot \vec{r}>) has only off-diagonal entries. But how does...
  16. andrewkirk

    Asymptotic properties of Hydrogen atom wave function

    I am working through an explanation of the wave function of the Hydrogen atom. I have got as far as deriving the version of Schrodinger's equation for the one-dimensional problem in which only the radial coordinate can vary: ##[-\frac{\hbar^2}{2m}\frac{\partial^2}{\partial^2...
  17. S

    Hydrogen atom: potential well and orbit radii

    Hello, I happened to open up an old book by Sah, and in it he says: "it is evident that the electron orbit radius is half the well radius at the energy level E_n" The orbit radius is r_n=\frac{4*\pi*ε_0*\hbar^2*n^2}{mq^2} and the potential well...
  18. X

    Time Evolution of Hydrogen Atom in a Magnetic Field

    Homework Statement A hydrogen atom is prepared in its ground state with spin up along the z-direction. At time t = 0 a constant magnetic field ##\vec{B}## (pointing in an arbitrary direction determined by ##\theta## and ##\phi##) is turned on. Neglecting the fine structure and terms...
  19. C

    Radial distribution function for H atom in ground state

    Homework Statement The normalized energy eigenfunction of the ground state of the hydrogen atom is ##u_{100}(\underline{r}) = C \exp (-r/a_o)##, ##a_o## the Bohr radius. For this state calculate 1)##C## 2)The radial distribution function, the probability that the electron is within a...
  20. B

    About the energy necessary to pull out the closest electron of a atom

    Dear friends, I was wondering what would be the necessary amount of energy to pull out the closest electron of an iron metal. I read that the energy required for the most distant electrons of the iron metal is about 9 thousand KJ/mol. Thanks my sages@
  21. L

    Stability of the Classical Rutherford Atom: A Hydrogen Example

    I know there are other things that fail about the rutherford atom but as the electron is accelerating and radiating away energy it would fall into the nucleus, my question is how much energy would the electron need to gain so that the classical atom could be stable a hydrogen atom for example
  22. B

    Layman understanding Atom movement with added energy

    Hello there, I've for a long time thought that movement energy is transferred through collisions, one atom hits another and transfers it's momentum (Billiard balls). When they're stuck in a rigid structure like a metal, they vibrate until the energy of vibration exceeds the energy of their...
  23. C

    Why does a silicon atom in a silicon lattice have 4 single bonds?

    Silicon has 14 electrons, this means if it fills up its first two shells it will have 4 electrons in the outermost shell (These are the valence electrons). This shell can have 18 electrons in it, so silicon can have 14 more electrons in its outermost shell. This means it could...
  24. A

    Probability Electron at Point: H Atom

    The problem I'm working on asks: At what radius does the probability of finding an electron at a point in the hydrogen atom fall to 50% of its maximum? I've already worked through the problem to find the probability at the maximum, which was to take the first derivative of r^2 e^(-2r/a) and...
  25. N

    Kinetic energy of a hydrogen atom in its ground state

    Homework Statement While playing around with basic QM, I tried using the hamilton operator to find the kinetic energy of a hydrogen atom in its ground state. I assume the wave function ##\psi_1## is known. However, I of course ran into problems... 1) in my solution attempt below, I end up with...
  26. A

    Atom Energy in Crystals: Gibbs Free Energy

    Does atom at the surface of a crystal have more or less energy than those in the bulk? And how does this relate to their Gibbs free energy?
  27. A

    What is the energy of an atom and does it exist when heat energy is absent?

    what is meant by energy of an atom? Does an atom with zero heat energy possesses any other form of energy?
  28. T

    Neutral atom and a point charge

    Homework Statement If the distance between a neutral atom and a point charge is doubled, by what factor does the force on the atom by the point charge change? (new force / old force) 2. The attempt at a solution Wouldn't the answer just be (new force / old force) = 0 since there is no...
  29. S

    Angular momentum of wavefunction in Hydrogen atom

    Homework Statement Electron in Hydrogen atom can be described with wavefunction ##\psi =\frac{1}{2}(\psi _1+\psi _2+\psi _3+\psi _4)## where ##\psi _1=\psi _{200}##, ##\psi _2=\frac{1}{\sqrt{2}}(\psi _{211}+\psi _{21-1})##, ##\psi _3=\frac{i}{\sqrt{2}}(\psi _{211}-\psi _{21-1})## and ##\psi...
  30. C

    Linear combination of wave function of a Hydrogen Atom

    Homework Statement I am given a linear combination of wave function of HYDROGEN ATOM Ψ=1/2(Ψ200 +Ψ310+Ψ311+Ψ31-1), where the subscripts are n, l, m respectively. I was asked to find all the possible outcomes when measuring Lx and their corresponding probabilities. Homework Equations...
  31. R

    Does the Dirac ground state of the H atom have an electron current?

    I have confounded myself with the following observation. Take the standard expression for the lowest energy Dirac 4-spinor solution of the Dirac equation with a Coulomb potential (the H atom ground state). Plug this into the standard expression for the 4-vector current and use values for the...
  32. B

    The electric field of an atom is puzzling to me

    I hope someone can make me understand this: an electron radiates in all directions, when it is circling around a proton its electric field should radiate both inside and outside the orbit , but it doesn't : an atom of helium He2 is neutral and the protons neutralize also the outgoing field of...
  33. U

    What happens to electric PE as n increases in a hydrogen atom?

    Homework Statement As one considers orbits with higher values of n in a hydrogen atom, the electric potential energy of the atom a)increases b)decreases c)remains same d)does not increase Homework Equations The Attempt at a Solution Energy of the atom in nth energy level is...
  34. U

    Collision between electron and H atom

    Homework Statement An electron with KE 5eV is incident on a H atom in its ground state. The collision A)must be elastic b)may be partially elastic c)must be completely inelastic d)may be completely inelastic More than one option may be correct Homework Equations The Attempt at a...
  35. R

    Special Relativity, AP French 6.10: Atom Emits Photon

    Homework Statement I'll copy down the exact phrasing, so there's no question that this is what we're being asked: "An atom in an excited state of energy Qo (as measured in its rest frame) above the ground state moves towards a scintillation counter with speed v. The atom decays to its...
  36. harjot singh

    Why Do Electrons in Covalent Bonds Not Remain Stationary?

    my question is that why electrons revolve in a covalent bonded atom where the force of attraction of the other atom to which electron is shared when put forces of attraction on it.it means that they then should stuck at single point rather than revolving in the atom,my another question related...
  37. D

    Hydrogen atom eigenstate: proving orthogonality of states

    Homework Statement Hey dudes So here's the question: Consider the first excited Hydrogen atom eigenstate eigenstate \psi_{2,1,1}=R_{2,1}(r)Y_{11}(\theta, \phi) with Y_{11}≈e^{i\phi}sin(\theta). You may assume that Y_{11} is correctly normalized. (a)Show that \psi_{2,1,1} is orthogonal...
  38. D

    Probability of measuring E in a Hydrogen atom, and expectation values

    Homework Statement Hey guys, so here's the question: The energy eigenstates of the hydrogen atom \psi_{n,l,m} are orthonormal and labeled by three quantum numbers: the principle quantum number n and the orbital angular momentum eigenvalues l and m. Consider the state of a hydrogen atom at t=0...
  39. T

    Hydrogen Atom Matrix Elements Related to Transition Probability

    Homework Statement Evaluate the matrix element <U210|z|U100> where by |Unlm> we mean the hydrogen atom orbital with it's quantum numbers. Homework Equations The Attempt at a Solution So where I'm getting stuck is on the integral, because the "U" portion of the wave function is...
  40. PsychonautQQ

    Solve L=2 Atom Problem: Find Min (L_x)^2 + (L_y)^2

    Homework Statement For an electron in an atom that is an l=2 state, find the smallest value of (L_x)^2+(L_y)^2. Homework Equations The Attempt at a Solution okay so L = (l(l+2))^(1/2) and that squared with l =2 would be 6h(bar)^2 kind of running into a wall here.. Or is it...
  41. L

    Energy of different energy levels of hydrogen atom

    Homework Statement A hydrogen atom is in 2p state, how many different energy levels are there if a magnetic field of 0.10 T is applied to it, and what are their energies? Make sure spin is included. Homework Equations U = -gmsμzB g is the Lande-g factor, which is about -2 for...
  42. L

    Probability of Helium Atom Speed >1000 m/s @ 300K

    Homework Statement Using classical statistics, find the probability that an atom of helium in a helium gas at temperature T = 300k will have a speed greater than 1000 m/s.Homework Equations I think this calls for the Maxwell speed distribution. F(v)dv=4πCe^{\frac{-mv^{2}}{2kt}}v^{2}dv Where k...
  43. L

    Probability of electron location in Hydrogen atom

    Homework Statement What is the probability that an electron in the ground state of hydrogen is within one Bohr radius of the nucleus? Homework Equations P_{nl}(r) = r^{2}|R_{nl}(r)|^{2} The Attempt at a Solution Since it's an electron in the ground state of a hydrogen atom, that...
  44. C

    Meso Atoms: Definition and Phthalocyanine Examples

    What is a "meso atom"? The class of compound I'm reading about is phthalocyanine: The article mentions "meso atoms" on the phthalocyanine molecule. What is a meso atom, and which of phthalocyanines atoms would be considered meso atoms?
  45. M

    Is it possible to change the chirality of an atom like this?

    Heres the chiral center: I want to change the chirality of the amino group. I was wondering if I can do it through some kind of nucleuphilic addition to the carbonyl group, while adding something to adding a metal that will coordinate the amino group and drag it back or force it to change...
  46. X

    Atom Balance: C & O for CO and O2 Reaction

    Homework Statement One mole of CO and 1/2 mole of oxygen are mixed and the products consist of CO2, CO, O2, and O. Write the atom balance for C and O. Homework Equations Mass conservation The Attempt at a Solution 1/2(O2)+CO2 -> aCO2 +bCO+cO2 +dO. a, b, c, d are unknowns. I make a table...
  47. G

    A hypothetical question about seeing an atom with the naked eye

    This is only hypothetical, but bare with me. I did some searching on the interweb and found out that a drop of water has about: 1.67 × 10^21 molecules (Source: http://wiki.answers.com/Q/How_many_water_molecules_are_in_one_drop_of_water) Also, the amount of protons and neutrons that can...
  48. D

    Electron far away from the nucleus of ground state H atom

    The wave function of an electron in ground state hydrogen atom is non-zero at points far away from the nucleus. Interpreted as the probability of finding the electron, this is telling us that there is a finite probability of finding an electron far away from the nucleus even if it is at ground...
  49. S

    Atom bomb nearly exploded over North Carolina in 1961

    What's one state when you got 50? http://news.yahoo.com/atom-bomb-nearly-exploded-over-north-carolina-1961-230654850.html
  50. A

    What is the Energy of One Hydrogen Atom?

    According to Einstein's equation, E=mc^2, I calculated the energy from one hydrogen atom to be roughly 5.01*10^-15 Newtons. I am unsure as to if this is correct. Please help me.
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