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. adf89812

    I can't apply my knowledge of shielding to explain the three slopes

    Also, why does red taper off slope towards the end of the subsequence, but green and purple never taper off in slope (flatten out)?
  2. seonjunyoo

    B I wonder about a particle's energy when mass is obtained or lost

    According to Einstein's formula, energy is generated when mass is obtained or lost. What does losing or gaining mass mean for an atom or particle valence? It's simply because of the formula I don't want this kind of answer I want. What does it mean for an atom or particle to lose or gain mass...
  3. Danielk010

    Do you graph the energy levels of a ##1s^1## atom the same as a ##1s^2## atom?

    From the first equation, there are 5 constants, e, ##\pi##, ##\varepsilon_0##, ##n^2##, and 32. The only difference is m, where helium has around four times the mass of hydrogen. What I don't get is if there is a difference between the energy levels of the hydrogen and the ionized hellium? Also...
  4. M

    B How Fast Do Different Atoms Vibrate?

    The "ticks" of the current standard atomic clocks are marked by the regular vibrations of an ensemble of cesium atoms, which vibrate 9.2 billion times every second How about other atoms, how fast does these vibrate ? And where is possible to ready about this ?
  5. scythe327

    B Can a hypothetical atom be made out of positrons and electrons ?

    I am a Computer Science Engineering student at a local university in India and I was really moved by the CERN youtube channel and it got me curious about the particles like electrons and protons, I love symmetry in nature and was not a huge fan of proton being nearly 2000 times the mass of...
  6. ergospherical

    I Average magnetic moment of atom in magnetic field ##B##

    from the partition function - am trying to show that ##\langle \mu \rangle = \beta^{-1} (\partial \log Z / \partial B)## where ##Z## is the canonical partition function for one atom, i.e. ##Z = \sum_{m=-j}^{j} \mathrm{exp}(\mu_0 \beta B m)##, and ##\mu = \mu_0 m##. The average...
  7. C

    B Atom energy band formation and electron allotment

    This is actually a two-part question: 1) According to the Copenhagen Interpretation, atoms have energy bands but there's no explanation of how these bands are derived, or why they only form for protons/antiprotons. Any thoughts? 2) The Copenhagen Interpretation mentions that when an atom's...
  8. Isaac0427

    I Weakly interacting electrons in an atom

    Consider electrons in atom, and let's mostly ignore interactions between the electrons for now. What I mean by that is that the lowest energy level is the doubly degenerate 1s, then the doubly degenerate 2s, then the 6-fold degenerate 2p, etc. Textbooks like Griffiths use term symbols...
  9. Lotto

    B What does this distance of an atom mean?

    I can look at it as if a vibrational motion of the atoms was a simle harmonic motion. So I can consider one of the two atoms to be at rest and the second one to vibrate. Its deviation can be written as ##x(t)=r(t)-r_0##. When I know that the hydrogen molecule stops exiting when the range of...
  10. uxioq99

    The Energy Expectation Value for a Moving Hydrogen Atom

    ##\begin{align} \langle E \rangle &= \int_{\mathbb R^3} \int_{\mathbb R^3} \int_{\mathbb R^3} \int_{\mathbb R^3} g^\dagger (\tilde K) g(K) |\psi_0(x)|^2 \left(E_0 +\frac{\hbar^2 |K|^2}{2m}\right) e^{i(K-\tilde K)\cdot X -\frac{i}{\hbar} \left(\frac{\hbar^2 |K|^2}{2m}-\frac{\hbar^2...
  11. topsquark

    A Solving the Radial Equation for the Dirac Hydrogen Atom Solution

    I'm going to be a bit sketchy here, at least to start with. If you want me to show you exactly where I am I might post a pdf, if that's okay. (Only because it will simplify coding several pages of LaTeX.) Briefly, what I'm trying to do is take this system of equations: ##F^{ \prime } +...
  12. S

    I Are the proton and electron quantum entangled in the hydrogen atom?

    The proton and electron are described by separate wavefunctions. When they come together in the hydrogen atom are they quantum entangled and have a joint wavefunction.
  13. M

    I Planck’s constant: Why are atom vibration frequencies integers only?

    Given the definition of whole numbers as integers, https://www.google.com/search?q=what+is+a+whole+number&rlz=1C1VDKB_en-GB&oq=what+is+a+whole+number&aqs=chrome..69i57j0i512l9.11619j0j15&sourceid=chrome&ie=UTF-8 Is it known why atom vibrations are only at whole numbers ( ref plank’s constant)...
  14. C

    I Is the magnetic moment of a hydrogen atom not equal to Bohr's magneton?

    Can you cite experiments where, in some excited states of a hydrogen atom, magnetic moment significantly differs from Bohr's magneton was detected? Correction for magnetic moment of nucleus is insignificant. Only experimental data, not theoretical forecasts. Starting from the experiments of...
  15. pokespriter

    I About the position of electrons (uncertainty)

    Hello guys, I don't know if this is the right place to ask, so please be kind :/ I have a question regarding the location of an electron that belongs to an atom. A teacher told me that the probability of an electron to be found within its orbital is around 99%. When I asked about the remaining...
  16. snoopies622

    I Why is the SE better than the KG equation for a hydrogen atom?

    my premises: — one can arrive at the Klein-Gordon equation by applying quantum mechanical operators to the special relativity dynamics equation E^2 = (mc^2)^2 + (pc)^2. — Schrodinger arrived at this equation, but rejected it because it didn't correctly explain the behavior of an electron in a...
  17. P

    I Can the Helium atom be solved by other methods?

    The schrodinger equation for helium is (−ℏ^2/2me(∇21+∇22)+V(r1)+V(r2)+V(r12))ψ=Eψ V(r12)=1/(r12-r1) which makes the equation inseparable. Can other methods be used to solve it.
  18. F

    I Microscope with which atoms can be seen

    The lowest price for a microscope that can... What is the cheapest (no not a cheap one but the cheapest) microscope from which atoms can be seen in? I don't need a big zoom into an atom. If possible I would just a zoom enough to see atoms as tiny spheres no structure. Example bellow (this one...
  19. R

    Quantum Books recommendation covering the Hydrogen atom and Kepler's laws (separately)

    Hi, I have an interview for masters degree program in 2 weeks and they asked to study two subjects thoroughly, first being Hydrogen atom and second being Kepler's laws. anyone recommends one book about each subject with advanced level questions that would help me understand the subjects to a...
  20. M

    A Magnetic sublevels of a random atom

    Hello! Assume I create an atom by some non-state-selective method (e.g. laser ablation, or hitting a proton on a target) and let's say that the atom is in a ##J=1## state. In the absence of magnetic fields, the ##m_J = 0, \pm 1## levels are degenerate. If I am to define arbitrary a z-axis (say...
  21. S

    I Microstates of an atom in an energy state

    I have a question about a sentence in the book Introduction to Thermal Physics (Daniel v. Schroeder). So in chapter 6, Schroeder talks about an atom isolated. This means its energy is fixed. The atom is in some state. The energy states of the atom have degenerated. All microstates with that...
  22. dom_quixote

    I Modern Atom Model: Is It Perpetual Motion?

    Is the current atomic model a kind of perpetual motion?
  23. Salmone

    I Matrix element in problem with hydrogen atom

    I have a problem in calculate a matrix element in a problem with hydrogen atom. I have an hydrogen atom and Hamiltonian eigenstates ##|n,l,m>## where ##n## are energy quantum numbers, ##l## are ##L^2## quantum numbers and ##m## are ##L_z## quantum numbers, I have to calculate the matrix element...
  24. guyvsdcsniper

    States in the Hydrogen Atom that are not allowed

    I am a little lost on how to approach this problem. What I know is the following: The r vector is in terms of x y and z hat. I know my two l=0 states can be the 1s and 2s normalized wave function for Hydrogen. Should I be integrating over dxdydz?
  25. J

    I Angular momentum of an atom within a rigid body in motion

    Considering an atom within a rigid body, does the angular momentum of an electron within the atom vary when the body is put in motion? My intuition is that, whether considered in a classical sense or quantum sense, the speed of a given electron in its motion within an atom will be constant and...
  26. Twigg

    I Does putting a hydrogen atom in a box mix angular momentum states?

    If you put a hydrogen atom in a box (##\psi=0## on the walls of the box), spherical symmetry will be broken so ##n##,##l##,##m_l## are no longer guaranteed to be good quantum numbers. In general, the new solutions will be a linear combination of all the ##|n,l,m_l\rangle## states. I know that...
  27. entropy1

    I Schrödinger's Cat and radioactive atom

    Particles can be made to be in superposition of their states. Concerning Schrödingers cat, if the cat is in superposition of being dead and alive, does that mean that the atom that drives the narcotic is in superposition of having decayed and not having decayed? And does that mean that any...
  28. H

    A What are the quantum numbers used to label helium atom eigenfunctions?

    Are there any results on the structure of the helium atom eigenfunctions? By this I'm referring to the non-perturbative structure of the eigenfunctions, AKA what are the quantum numbers that one would use to label the eigenfunctions?
  29. A

    I Question about the Bohr model of atom and and electron in an orbital

    I have a question about what happen when an electron in the Bohr model of atom, gains energy because for example is "hitting" by a photon. Electron have an energy, and it is the sum of potential and kinetic. When they gain energy, they gain potential energy so they go further away from nucleus...
  30. P

    I What gives an optimum value for electron energy to ionise atom?

    There is an optimum energy which gives the greatest probability of ionisation of a particular element. This is said to align with the wavelength of the electron being close to resonances in the atom. Looking at this in a different way as particles, would it be correct to say that the optimum...
  31. R

    B Is it the nucleus or a proton at the center?

    Which one is closer to reality, is it this picture https://en.wikipedia.org/wiki/Hydrogen#/media/File:Hydrogen_atom.svg or this https://www.naturphilosophie.co.uk/heart-hydrogen-atom/? The reason why I asked the question is according to the picture of hydrogen atom at Wikipedia, which is the...
  32. rudransh verma

    I How Does Heat Transfer Impact Our Sensation of Temperature?

    We know heat is the motion of molecules of a gas for example. As temperature increases this motion increases and the gas expands. We know this gas would be hot if we touch it. So I want to ask how does the fast motion of molecules somehow translates to the heat that we feel. Why does it feel...
  33. M

    B Could Spontaneous symmetry breaking cause momentum change in an atom?

    If you were to fire a single atom from a fixed point into a chamber of perfect vacuum and measure where it collides with the opposite wall. Could Spontaneous symmetry breaking in the sub atomic particles cause momentum change in the atom, changing the part of the wall the atom interacted with?
  34. M

    I Dirac equation in the hydrogen atom

    Hello! I went over a calculation of the hydrogen wavefunction using Dirac equation (this one) and I am a bit confused by the angular part. The final result for the wavefunction based on that derivation is this: $$ \begin{pmatrix} if(r) Y_{j l_A}^{m_j} \\ -g(r)...
  35. F

    De-excitation of a moving atom with photon emission

    The information I have are the following: ##p^\mu=(E, p, 0, 0)## ##p'^\mu=(E', p'\cos\beta, -p'\sin\beta,0)## ##k^\mu=\tilde{E}(1, \cos\alpha, \sin\alpha, 0)## Where: ##E=\sqrt{M^2+p^2}## ##E'=\sqrt{m^2+p'^2}## Using the conservation of the four-momentum ##p^\mu=p'^\mu+k^\mu##...
  36. O

    I General solution of the hydrogen atom Schrödinger equation

    Hello everyone! I have two questions which had bothered me for quite some time. I am sorry if they are rather trivial. The first is about the general solution of the hydrogen atom schrödinger-equation: We learned in our quantum mechanics class that the general solution of every quantum system...
  37. Magnetons

    Why do we use Bohr's model of the atom in electrostatics?

    Why we use Bohr's model of atom in electrostatic?
  38. P

    B Can a hydrogen atom become a neutron?

    I read this from Nasa's website: "Within the first second after the Big Bang, the temperature had fallen considerably, but was still very hot - about 100 billion Kelvin (1011 K). At this temperature, protons, electrons and neutrons had formed, but they moved with too much energy to form atoms...
  39. R

    Get the mass of an argon atom and its molecular weight from Cv

    I don't see how isolate m or M. That is, how to get rid of <v^2> which is how I wrote the average of v2
  40. bbbl67

    I A large normal atom, but with a muon in its outer shell?

    So let's say we have a large neutral atom, e.g. gold with 79 electrons around it. Let's say we replace its outermost electron with a muon. Muons orbit closer to the nucleus than electrons, much closer. Will the outermost muon be closer into the nucleus than even its innermost ground-state...
  41. Elon Musk

    Nuclear Physics help please (alpha decay of a Po-216 atom)

    I think that when an atom of polonium (Po-216) is moving slowly enough that it can be considered to be at rest. The Po-216 undergoes alpha decay and becomes lead ( Ph-212 ), via the reaction 깝 Po → Pb + ta. After the decay. the lead atom is moving to the left with speed v. and the alpha particle...
  42. N

    B Energy needed for electron's change in energy level in an atom

    Textbooks always give an explanation for why electrons move between energy levels in atoms with an explanation something like this: 'An electron can jump to a higher energy level if it absorb's energy which exactly matches the difference between final and initial energy level'. My question...
  43. M

    B Are photons entangled with a component of the atom that emitted them?

    If an atom were made to release a Photon, then a number of the components of the atoms nucleus were theoretically extremely quickly removed. would the previously emitted photon change wave length?
  44. agnimusayoti

    Verify the average value of (1/r) for a 1s electron in the Hydrogen atom

    For spherical coordinate, ##dV = r^{2} \sin {\theta} dr d\theta d\phi## Therefore, $$<\frac{1}{r}> = \frac{1}{(\pi)(a_0)^{3}} \int_{0}^{\infty} {r e^{\frac{-2r}{a_0}} dr \int_0^{\pi} \sin {\theta}} d\theta \int_0^{2\pi} d\phi$$ From partial integral, I've found: $$\int_{0}^{\infty} r...
  45. B

    I Confused about dressed states of atom

    Hello! Assume we have a 2 level system, with the ground state defined as the zero energy level and the excited state having an energy of ##\omega_0##. If we apply an oscillating electric field (assume dipole approximation and rotating wave approximation) of frequency ##\omega##, we have a time...
  46. Helena Wells

    A Crystal structures and number of bonds of each atom

    Is there a general rule for a crystal structure how many bonds each atom in the crystal lattice will make ?For example Si has a face centered cubic structure so it makes 4 bonds regardless of the fact Si has 4 valence electrons?
  47. R

    I General Magnetic Dipole Moment For an Electron in an Atom

    On the first attached page ##\mu_z## is associated with orbital angular momentum (Eq. 41.34). On the following pages (Eq. 41.38) it is associated with spin angular momentum? Are these both part of the same thing? I tried to read further but the book does not address this. In example 41.6 it...
  48. Tuca

    I Solving Schrödinger's equation for a hydrogen atom with Euler's method

    Hi, first-time poster here I'm a student at HS-level in DK, who has decided to write my annual large scale assignment on Schrödinger's equation. My teacher has only given us a brief introduction to the equation and has tasked us to solve it numerically with Euler's method for the hydrogen atom...
  49. docnet

    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...
  50. 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...