What is Hydrogen atom: Definition and 408 Discussions

A hydrogen atom is an atom of the chemical element hydrogen. The electrically neutral atom contains a single positively charged proton and a single negatively charged electron bound to the nucleus by the Coulomb force. Atomic hydrogen constitutes about 75% of the baryonic mass of the universe.In everyday life on Earth, isolated hydrogen atoms (called "atomic hydrogen") are extremely rare. Instead, a hydrogen atom tends to combine with other atoms in compounds, or with another hydrogen atom to form ordinary (diatomic) hydrogen gas, H2. "Atomic hydrogen" and "hydrogen atom" in ordinary English use have overlapping, yet distinct, meanings. For example, a water molecule contains two hydrogen atoms, but does not contain atomic hydrogen (which would refer to isolated hydrogen atoms).
Atomic spectroscopy shows that there is a discrete infinite set of states in which a hydrogen (or any) atom can exist, contrary to the predictions of classical physics. Attempts to develop a theoretical understanding of the states of the hydrogen atom have been important to the history of quantum mechanics, since all other atoms can be roughly understood by knowing in detail about this simplest atomic structure.

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  1. K

    I When does the separation of variables work

    When studying the hydrogen atom, given that the potential depends only on the distance and not an any angle, we can do a separation of variables of the wavefunction as the product between a function depending only on the distance between particles (protons and electrons) and a spherical...
  2. S

    B What is the distinction between the Weak and Strong Equivalence Principles?

    I'm reading Carroll's GR book. I'm able to follow the introduction so far, but a couple of paragraphs are a bit hard to decipher: What exactly does "couples to" mean? Right now that's just a vague phrase to me that implies gravitational field has something to do with EM - but what's the...
  3. Dogya

    Hubble Constant: Force Acting on Hydrogen Atom Due to Expansion of Universe

    TL;DR Summary: Express through the Hubble constant the force that acts on the hydrogen atom due to the expansion of the universe We have a hydrogen atom, in a gravitationally bound system nothing interesting happens to it. Let's put it in an empty world with only an electron and a proton...
  4. 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...
  5. 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 } +...
  6. 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.
  7. H

    Difference between average position of electron and average separation

    Hi, I asked this question elsewhere, but I didn't understand the answer. It seems to be easy to understand, but for some reason I'm really confuse. I'm not sure how to find the average position of an electron and the average separation of an electron and his proton in a hydrogen atom. To be...
  8. J

    I Two hydrogen atoms and Pauli's exclusion principle

    Hello, I recently came across the following (apparent, I hope) paradox: suppose we have two H atoms. Now, a hydrogen atom is made up of one proton and one electron (fermions), so it is a boson. Then one could have two hydrogen atoms which are in the exact same state (including position). This...
  9. 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...
  10. 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...
  11. 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...
  12. 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...
  13. 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?
  14. Mr_Allod

    Probability of finding a pion in a small volume of pionic hydrogen

    Hello, I am trying to figure out the right way to approach this. First of all, other than the different Bohr radius value, does the change to a negative pion make any other difference to calculating the probability? Also what would be the correct way to apply the "small volume"? What I'm...
  15. 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...
  16. Viona

    Spin-Orbit Coupling in Hydrogen Atom: Understanding the Calculation

    I was reading in the Book: Introduction to Quantum Mechanics by David J. Griffiths. In chapter Time-independent Perturbation Theory, Section: Spin -Orbit Coupling. I understood that the spin–orbit coupling in Hydrogen atom arises from the interaction between the electron’s spin magnetic moment...
  17. 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)...
  18. Viona

    B The average value of S operator

    While reading in the book of Introduction to Quantum Mechanics by David Griffith in the section of Fine structure of Hydrogen: spin- orbit coupling, he said that the average value of S operator is considered to be the projection of S onto J. I could not understand why he assumed that. please...
  19. 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...
  20. 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...
  21. 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...
  22. 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...
  23. 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...
  24. 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...
  25. 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}
  26. 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?
  27. 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...
  28. 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...
  29. 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...
  30. 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.
  31. 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] =...
  32. P

    Case when the potential energy of the 1st excited state is zero

    I know how to solve this problem when the energy at ground state is zero but I don't know how to deal with 1st excited state energy as zero. According to me since the potential energy is zero therefore the kinetic energy must be 13.6eV according to conservation of energy. I also know that the...
  33. 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...
  34. 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...
  35. 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...
  36. 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?
  37. patric44

    A problem in solving Schrodinger equation for hydrogen

    hi guys i am having a little problem concerning the theta part of TISE : its clearly that its very similer to the associated Legendre function : how iam going to change 1/sinθ ... to (1-x^2) in which x = cosθ i tried many identities but i am stuck here . any help on that ?
  38. 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?
  39. 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...
  40. F

    I Solving the Quantum Mechanics of a Hydrogen Atom

    Hello, I have a little problem understanding the quantum mechanics of a hydrogen atom. Im troubled with the following question: before i measure the state of a (simplified: without fine-, hyperfinestructure) hydrogen atom, which is the right probability density of finding the electron? is it...
  41. astrocytosis

    Darwin term in a hydrogen atom - evaluating expectation values

    Homework Statement Homework Equations VD= -1/(8m2c2) [pi,[pi,Vc(r)]] VC(r) = -Ze2/r Energy shift Δ = <nlm|VD|nlm> The Attempt at a Solution I can't figure out how to evaluate the expectation values that result from the Δ equation. When I do out the commutator, I get p2V-2pVp+Vp2. This...
  42. R

    I Question about one electron hydrogen atom angular moment

    Hi, I'm having trouble understanding angular moment of the one electron hydrogen atom. Solving Schrodinger equation on a referece system (say S) I get the energy eigenstates. They depend on three quantum numbers, n, l, m \frac{-ħ}{2 m}\nabla^{2} \Psi - \frac{e^{2}}{4 \pi \epsilon r} \Psi =...
  43. Another

    Wave function in a hydrogen atom : normalization

    Homework Statement Determined wave function in a hydrogen atom. ## Ψ(r,θ,Φ) = A(x+iy)e^{ \frac{-r}{2a_0}}## << find A by normalization Answer of a question in my book is ## A = -\frac{1}{a_0 \sqrt{8 \pi}} (\frac{1}{2a_0})^{3/2} ## Homework Equations ## \int Ψ^*(r,θ,Φ)Ψ(r,θ,Φ) d^3r = \int \int...
  44. Rupul Chandna

    I Why is separation constant l(l+1) instead of +-l^2?

    While separating variables in the Schrodinger Equation for hydrogen atom, why are we taking separation constant to be l(l+1) instead of just l^2 or -l^2, is it just to make the angular equation in the form of Associated Legendre Equation or is there a deeper meaning to it?
  45. E

    First order perturbation energy correction to H-like atom

    Homework Statement Real atomic nuclei are not point charges, but can be approximated as a spherical distribution with radius ##R##, giving the potential $$ \phi(r) = \begin{cases} \frac{Ze}{R}(\frac{3}{2}-\frac{1}{2}\frac{r^2}{R^2}) &\quad r<R\\ \frac{Ze}{r} &\quad r>R \\...
  46. It's me

    Dirac hydrogen atom vs spin symmetry

    Homework Statement Exact spin symmetry in the Dirac equation occurs when there is both a scalar and a vector potential, and they are equal to each other. What physical effect is absent in this case, that does exist in the Dirac solution for the hydrogen atom (vector potential = Coulomb and...