# atom Definition and Topics - 62 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. ### 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...
2. ### I What is heat Actually?

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...
3. ### 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.
4. ### 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...
5. ### 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?
6. ### 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...
7. ### I Why an electron gets knocked out of an atom instead of going to a higher energy level

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...
8. ### I How does the collision between two atoms work?

Considering the quantum mechanical model for an atom, what exactly happens when two atoms (say, two Ca2+ ions in a Brownian motion) collide with each other? As I know, this collision is not like a regular elastic or inelastic collision between two macroscopic objects. Is it mainly due to the...
9. ### Why doesn't the atom absorb heat energy when it is low?

(In my last thread) Mentor Dale said: " An atom in the ground state can absorb energy from the environment including thermal radiation. Once it has done so it will be excited and will no longer be in the ground state. An excited atom can radiate and go to a lower energy state, but an atom in the...
10. ### I Doesn't the atom in ground state radiate?

According to textbooks, an atom in ground state doesn't radiate. Yet I got some other idea after reading Wu Ta-you's theoretical physics book. I hold the viewpoint that the atom does radiate, and at the same time it absorbs energy from heat radiation in its environment. The energy it radiates...
11. ### A Nuclear and Atomic energy levels

I've noticed that in the Shell Model of the nucleus, the order of the energy levels is 1s, 1p3/2, 1p1/2, etc. While in the atomic energy levels it goes 1S 2S 2P, ... But they still take the same amount of particles for each level in both the atomic and nucleus. Am I missing something here? Or...
12. ### Oddly specific number of elements

There are 118 elements known to man, and some scientists like Feynman think that element 137 might be the end of the Periodic Table. Isn't that oddly specific? To me, it feels like it is completely random and of no significance. What is going on here? Is there a constant that relates to this...
13. ### I Pauli principle and coupling term in Weizsäcker formula

Consider the pairing term in Weizsäcker formula. Here https://en.wikipedia.org/wiki/Semi-empirical_mass_formula#Pairing_term it is claimed that: I don't understand how Pauli exclusion principle should be the cause of this. This term comes from spin-spin interaction (or "coupling"), but I do...
14. ### B Who drew the first model of the atom?

Does anybody know who first drew (not just described but actually drew, even roughly) a model of the atom like the one below, and when: I'd appreciate it if anybody can point me to an evidence.
15. ### I Transition energy 2p to 1s

I shall calculate the 2p → 1s transition energies for hydrogen, deuterium (one proton plus one neutron in the nucleus), and positronium (bound state of an electron and a positron). My problem with this exercise is that I couldn't find a formula to calculate the transition energies. Can someone...
16. ### B What does the 'space' inside an atom consist of?

Atoms make up all the material stuff around us, but most of an atom is empty space. The nucleus at the centre of an atom (99.95 percent of its mass) is orbited by tiny electrons (only 0.05 percent or less of the overall atomic mass). And as you've probably heard, an analogy is to think of the...
17. ### B How the atom was proven to exist?

How come atom was proven to exist just because the electron was discovered in 1874, atom was like a fad of truth on early 1800s right, where atom was pictured at that time like a small brick of ball and nothing else (no electrons, neutrons, protons, parts, etc) and on that year also, chemistry...
18. ### I Particle Focusing using EM fields

Good day all! I have a question that has been in my head bouncing around for a while and I figured the best resource would be here as I can't find anymore related information (Or I am just looking in the incorrect spot). My apologies if this is in the wrong section I wasn't too sure where to...
19. ### How exactly does the electric force act?

greeting How exactly the electric force acts .The definition of force is In physics, a force is any interaction that, when unopposed, will change the motion of an object. as the electron circulates around the nucleus of the atom because of that I do not see how that force acts .
20. ### Quantum Jump that produces an infrared line?

1. A certain type of atom has only four energy levels, as shown in the diagram. The "spectral lines" produces by this element are all visible, except for one infrared line. The quantum jump that produces the infrared line is: (see attached file) A) state 4 to 3. B) state 4 to 1. C) state 2...
21. ### Gauss' Law Diatomic Hydrogen

Say you had two isolated hydrogen atoms. Because of the spherical distribution of electronic charge on each hydrogen and the net charge of 0 outside each atom, wouldn't Gauss's law dictate a 0 net electric field outside each atom? If this is the case, why does diatomic hydrogen so readily form...
22. W

### How does the Pauli Exclusion Principle in this problem?

Homework Statement This is not a homework problem. It's an example in a text book. 3 electrons. For ##S=3/2##, we have that $$m_{s_1} = m_{s_2} = m_{s_3} = 1/2$$ Therefore by the Pauli Exclusion principle, $$m_{l_1} \neq m_{l_2} \neq m_{l_3}$$ and they take the values ##-1,0,1##...
23. ### I Calculate the energy of the electron in a non-H like atom

Hello mates. I was doing some research about Rydberg atoms, and I came up with this question: what's the energy of an electron in n energy level in an atom which is NOT hydrogen-like, that is, an atom with more than 1 electron? How can we calculate it? What if the electron we are studying is in...
24. ### I A question about a particle's de Broglie wavelength

For electron scattering experiment which measures charge radius of the nucleus, it's said that energies of scattering electrons (or protons) must be such that their wavelength size is of the same order as nuclear dimensions. While i understand why this must be true I'm not entirely sure. My...
25. ### I How can an atom change from ground to excited state?

I am currently studying a Foundation Program, which includes chemistry. -I can easily understand the distinguishable characteristics between ground and excited state via writing the electron configuration. -But how can an tom changes from ground to excited state ? And can an atom changes from...
26. ### I Equation for modeling atomic spectra of all atoms

I've seen the equation I think is just for hydrogen. is this just for hydrogen? of course this doesn't return the atomic spectra, it returns the energy. So using E=h*v and Planck's constant. a simple factor of 1/h would return the frequency. right? Energy is directly proportional to frequency...
27. ### I Predicting new crystal structures

Hello, Sorry if this is a rather basic question, but my memories of solid-state chemistry are a bit rusty. Basically I'm trying to predict new crystal structures. I understand the crystallographic aspects quite well and know that at given external temperature and pressure the most stable...
28. ### B Atoms without electrons

hello everybody :) Let's assume that we could steal all electrons of an atom. What would happen? How would the atom change its properties? Could we measure different values?
29. ### I Exchange of photons inside atoms

I was reading Feynman Diagrams and stumbled upon this query: If the electrons and protons interact by exchange of photons, does the electron inside an atoms also interact with the nucleus with a similar kind of exchange?
30. ### Kinetic energy of the hydrogen atom in its ground state

I saw another post about this but i didn't quite find what i was looking for there so i thought i'd give it a go instead with a thread. Homework Statement Calculate the exact value of the kinetic energy of the hydrogen atom in its ground state. No more information is given, we are referred to...