Atom Definition and 999 Threads

Now, from what I understand, Bohr's model of the atom is outdated and flawed. But whenever I imagine energy levels, it is the Bohr's model that comes to mind. Do electrons really orbit around the nucleus? I would assume because of classical physics, even though the electron can be on any portion...

I hate to discourage anyone from doing science ("Stand Back!" indeed), but this goes a bit too far. While I admire his enthusiasm, if I lived next to this guy I'd be concerned.

http://hosted.ap.org/dynamic/stories/E/EU_SWEDEN_NUCLEAR?SITE=AP&SECTION=HOME&TEMPLATE=DEFAULT&CTIME=2011-08-03-11-33-45 STOCKHOLM (AP) -- A Swedish man who was arrested after trying to split atoms in his kitchen said Wednesday he was only doing it as a hobby.

Is there any derivation of the bohr model for hydrogen using Ehrenfest theorem. References are appreciated.

I do not understand if you accelerate a hydrogen atom to 90% the speed of light its mass is greatly increased. Are the forces that hold it together increased? If not how is it different, will it fall apart? If the forces are increased in relationship to the mass of the atom the energy...

Homework Statement Use [H_{0},r_{j}]=\frac{i\hbar}{\mu}p_{j} for the Hydrogen atom (where the j's denote the jth components in Cartesian coordinates) to prove that <n_{f},l_{f},m_{l,f}|p_{j}|n_{i},l_{i},m_{l,i}>=-i\mu\omega<n_{f},l_{f},m_{l,f}|r_{j}|n_{i},l_{i},m_{l,i}> Homework...

as i know,bohr's discovery reveals that atom consist of central nucleus and electron orbit around them in empty spaces my question is-why aren't virtual particles being produced in those empty spaces?

Homework Statement So I've been racking my brain around the hydrogen mean values. \left\langle \frac{1}{r}\right\rangle=\frac{1}{a_0n^2}, that I can solve with the recurrence relation in Schaum: \left\langle r^k\right\rangle=\int_0^\infty r^{k+2}|R_{nl}(r)|^2dr by simply putting in...

Homework Statement part b) Calculate the recoil shift for the emission of the most energetic Lyman line from a free atom of hydrogen. 2. The attempt at a solution My question isn't a physics one per se, I'm stuck on terminology. What is meant by "the most energetic Lyman line"? I'm use...

Imagine that:- When a nucleus suddenly dissapears in an atom .What are the changes occurred around an atom .

For a summer class, I’ve been trying to get the quantum picture of an atom at least in conceptual terms, no math. I understand how, if you think about an atom like a one-dimensional box, an s orbital is like the first fundamental wave, and a p-orbital is like a sine wave, and I understand how...

Seems like a simple questions just got into a little bit of a debate, and need some clarification. Is the Atom and its particles proven?

Most common isotopes of He has 2 neutrons, Li has 3 neutrons and so on right, until Z increases to higher numbers and we get to elements like iron, where the nucleus doesn't have equal numbers of protons and neutrons anymore. But why isn't the number of protons and neutrons equal in the most...

I noticed many PF threads mention ground state of Hydrogen atom. At the same time it is two body problem considered to be solved by separation of variables. It is true, of course, that we can find basis wave functions (solutions of Shroedinger equation). But why does anybody think, that...

If a photon is not absorbed by an atom during collision, what determines the direction of the reflected photon? Explicitly... Does the photon reflect off of the valence probability 'shell' by abiding angle of incidence = angle of reflection? This seems counter-intuitive to me because some...

Homework Statement The electron in the Hydrogen atom can be replaced by the heavier muon resulting in a muonic atom. The muonic atom is not stable because the muon lives for 2.2 μs on average and then it decays into an electron and two neutrinos. However some very fast experiments can be...

Homework Statement The mass of an atom can be determined by ionizing it and accelerating it through a known electric field followed by a known magnetic field. The ion’s circular path is then measured. Calculate the mass of a chlorine anion of charge 3.20 x 10^-19 C if it follows a circular...

Just a quick question regarding the solution of the hydrogen atom: is it possible to solve the hydrogen atom problem via creation and annihilation operators as is the case with the harmonic oscillator? Any help here greatly appreciated! Crawf.

hi does anybody of you know if there is an equation that describes an atom in a gravitational field of a star or something like that (general relativity or Newton)or do you know some results that could tell me something about the magnitude of this energy corrections? do you know a method...

A hydrogen atom placed in an electrical field results in a changed energy level and a changed eigenfunction, compared to the free atom. To examine this effect, we choose a homogenous electrical field of the force F, whose field lines run along parallel to the z-axis. The Schrödinger equation is...

I was deriving Bohr model formulas and I stumbled upon a problem. When I use the postulate that says that you can apply Newtonian Mechanics to orbiting electron, I wrote the Coulomb's force as following: Fc=(-e)*Z*e/(4pi(epsilon0)*r^2) Minus from the electron means that the force...

Hello! I'm preparing for my quantum mechanics test. In the solutions of an old test I find this conversion, that I don't understand. \Psi = Nze^{-r/2a_0} = Nre^{-r/2a_0}cos\Theta N is the normalization constant, which is to be calculated. I would have guessed that z is the atomic...

Hi there! I don't know if this is the right place but I wanted to know and learn from someone the difference between an atom and a sub-atom. H2O's molecule consists of 1 oxygen atom and 2 hydrogen atoms, right, but what do people mean when they mention "at subatomic levels"? Are sub-atoms what...

I have a question about the stability of positronium. Positronium consists of an electron and a positron whereas hydrogen consists of an electron and a proton. The energy levels of positronium, ignoring fine structure, are -6.8eV/n2 whereas those for hydrogen are -13.6eV/n2. My question...

Homework Statement A helium atom had two electrons in the first shell (1s). Explain, withour detailed derivation, what the value of the total spin quantum number is. Homework Equations ? The Attempt at a Solution Since the 2 electrons are in the first (1s) shell they must have...

1. Hello, I have some questions on my homework which are not so clear. The professor asked for " since the binding energy of the D-μ(it is muon) is much bigger than that of ordinary deuterium atom De, explain what will happen if a beam of muons is directed through a gas of ordinary De atoms...

Hi, I was wondering if the bound solutions to the radial part of the hydrogen atom form a complete set for the functions in L^2(0,\infty). I know that the laguerre polynomials are complete and that they only differ from the radial solutions by factors of x^l * exp, so I thought that they would...

As I understand it, "nonradiative decay" of a system from an excited state to a lower-energy state is any type of decay that does not result in the emission of an electron. I can't think of any way that a free atom could decay without emitting a photon. Molecules, yes, (through...

Hey, probably a stupid question but I can't seem to find an answer anywhere. Is a hydrogen free radical just a single hydrogen atom? A hydrogen atom has an unpaired electron bound right? Thanks in advance

Hi guys, Just got a question I'm a little stuck on and would love a push in the right direction Q) Using Hartree's theory calculate the degeneracy of the ground state of the Sodium atom. Its a previous exam question and I'm struggling to find much descriptive information about the topic...

Homework Statement An electron of know KE collides with a hydrogen atom in its ground state. With what possible KE may it rebound? KE = 11.5 eV 2. The attempt at a solution I assumed that the electron may either hit an orbiting electron and excite him (maximum layer is n = 2, change in KE...

hi i asked myself, is it correct to use the ordinary partition function and cut it off at some value to describe the atom at some finite temperature? or is there a better way to do this calculation? and if i evaluate the partition function for let me say n=2. does this mean, that the...

I haven't posted any of my working for this as I only want to check my answer. Q. For a hydrogen atom with n=2, l=1, m=0 calculate <r^2> My answer = 0.75 * a^2 where a is the bhor radius. Am I right?

Homework Statement I need to calculate the probability distribution of 1s and 2p state of hydrogen atom in momentum and in coordinate representations. I have calculated the wave function in coordinate representation, and the dilemma is, do I simply do the Fourier transform for given wave...

Homework Statement Hi In my book, they do calculations on a 2-level atom. After some approximations, they reach the following equation for the coefficient for the first (lower) level: c_1(t)\approx c_1(0)e^{-i|\Omega|^2t/\delta} where Omega is the Rabi frequency and delta is the...

Homework Statement Define the quantum numbers required to specify the state of an electron in hydrogen. The spatial part of the wave-function describing a particular hydrogen atom has no angular dependence. Give the values of all the angular momentum quantum numbers for the electron...

it is obvious that the hamiltonian of an atom is time reversal invariant but how can an atom have non-zero magnetic moment?

Hydrogen Atom ---> Uncertainty Principle Hey guys, I'm having some trouble with this one. [PLAIN]http://img849.imageshack.us/img849/2039/physhw.jpg How do I get started?

If the proton in the nucleus of, say a hydrogen atom, exerts an attractive force on an electron that is in orbit, why doesn't the electron move towards the proton? And does this have anything to do with the electric force being the centripetal force?

I can think of two things. Stimulated Emission and Absorption. Would it be possible to do an experiment where you could control coniditions to allow just these two outomes? Thanks

Also, when an atom emits light when another particle hits it, why does one of the electrons move to the outer shell?

I'm dealing with this problem for an MCAT review: Following beta-emission by a neutral atom at rest, the respective linear momentums of the beta(-) particle and the resulting atom are shown below. (see attachment for message) It wasn't too difficult to see that an extra force is in play, and...

I have confused myself with this by reading a combination of Wikipedia, books and my QM notes and I'm afraid I need someone to untangle me please. Basically what I want to know is, what are the consequences of the Pauli exclusion principle for the ground state of the helium atom? Here's my...

Ok so my problem is I have absolutely no idea where to start. I have been able to figure out other problems but this I can't get my head around. I am unsure as to the equations I need to use for collisions and how to obtain the correct answer. Homework Statement A nuclear reactor (see...

Explain how an atom may have a permanent magnetic dipole moment? Many thanks...

Consider a hydrogen atom whose wave function is at t=0 is the following superposition of energy eigenfunctions nlm(r) (r, t=0) = *[2100(r) -3200(r) +322(r) What is the probability of finding the system in the ground state (100? in the state (200)? in the state (322)? In another energy...

Consider a hydrogen atom whose wave function is at t=0 is the following superposition of energy eigenfunctions \psinlm(r) \Psi(r, t=0) = \frac{1}{\sqrt{14}} *[2\psi100(r) -3\psi200(r) +\psi322(r) What is the probability of finding the system in the ground state (100? in the state (200)? in...

I had this https://www.physicsforums.com/showthread.php?p=3200140#post3200140", which I posted on PF. I got the answer, but then I started thinking more about it and have some theoretical questions. If you did have this particle of mass m in a box of length L, which you are trying to stop...

Homework Statement A K shell electron is ejected from a tungsten atom. The result of this is the emission of a characteristic x-ray proton. (The binding energy of the K shell in tungsten is 69.5keV. The binding energy of the L shell in a tungsten atoms is 10.5 keV). a) If the vacancy in the K...

The question is: Which species has exactly five pairs of electrons around the central atom? (A) ClF5 (B) SF4 (C) SF5– (D) XeF4 The answer is B. Can someone explain why? I'm not too good with these geometries that use the d-orbital.