What is Bohr model: Definition and 100 Discussions

In atomic physics, the Bohr model or Rutherford–Bohr model, presented by Niels Bohr and Ernest Rutherford in 1913, is a system consisting of a small, dense nucleus surrounded by orbiting electrons—similar to the structure of the Solar System, but with attraction provided by electrostatic forces in place of gravity. After the cubical model (1902), the plum pudding model (1904), the Saturnian model (1904), and the Rutherford model (1911) came the Rutherford–Bohr model or just Bohr model for short (1913). The improvement over the 1911 Rutherford model mainly concerned the new quantum physical interpretation.
The model's key success lay in explaining the Rydberg formula for the spectral emission lines of atomic hydrogen. While the Rydberg formula had been known experimentally, it did not gain a theoretical underpinning until the Bohr model was introduced. Not only did the Bohr model explain the reasons for the structure of the Rydberg formula, it also provided a justification for the fundamental physical constants that make up the formula's empirical results.
The Bohr model is a relatively primitive model of the hydrogen atom, compared to the valence shell atom model. As a theory, it can be derived as a first-order approximation of the hydrogen atom using the broader and much more accurate quantum mechanics and thus may be considered to be an obsolete scientific theory. However, because of its simplicity, and its correct results for selected systems (see below for application), the Bohr model is still commonly taught to introduce students to quantum mechanics or energy level diagrams before moving on to the more accurate, but more complex, valence shell atom. A related model was originally proposed by Arthur Erich Haas in 1910 but was rejected. The quantum theory of the period between Planck's discovery of the quantum (1900) and the advent of a mature quantum mechanics (1925) is often referred to as the old quantum theory.

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  1. 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...
  2. C

    I Quantization of Quasiperiodic Orbits in the Bohr-Sommerfeld Model

    Recall that in the semi-classical Bohr-Sommerfeld quantization scheme from the early days of quantum mechanics, bound orbits were quantized according to the value of the action integral around a single loop of a closed path. Clearly this only makes sense if the orbits in question permit closed...
  3. F

    Bohr Model - Absorbing a Photon with Enough Energy to Ionize the Atom

    I just want to confirm something. You need about 13.6 eV of energy to ionize a hydrogen atom in the ground state. Can the atom absorb a photon with 15 eV of energy? I think it can. This would free the electron, and the freed electron would move off with a kinetic energy of 15 minus 13.6 eV...
  4. I

    I Bohr model for electron energy states

    I know that we use quantum mechanic and wave function to calculate probability of finding electrons but is there anything valid about bohr model that we still use it?
  5. patric44

    Chemistry Why does this equation not give me the ionization energy of lithium?

    i am trying to calculate the first ionization energy for lithium with this equation but it seems to work only with hydrogen ? i put nf = infinity and ni =2 ,and z = 3 for lithium and it gives about 30 ev not 5.39172 ev which is the value for lithium : i will appreciate any help in this
  6. C

    Conflict Between Infinite energy levels and Valence Shells

    Homework Statement I'm having trouble understanding the existence of valence shells. I understood that valence shell is the last energy level for the electrons to populate around an atom. But, according to Bohr model , an atom can have infinite energy levels , so I don't understand: How can...
  7. T

    Rutherford model of atom and Bohr model

    Homework Statement Question a) Briefly describe the Rutherford model of the hydrogen atom and mention any inadequacies that it might have. b) Describe the Bohr model of the hydrogen atom, and indicate the significance of the quantum number 'n' in the Bohr model. Homework EquationsThe Attempt...
  8. J

    Bohr Model Modifications into the Rutherford Model

    Good afternoon. Which modifications did the Bohr model introduce into the Rutherford one to justify the Discountinuous atomic spectra, specially the one for the Hydrogen atom? Thanks
  9. R

    Does r=mv/Bq hold true considering Maxwell's E.M wave theory?

    Homework Statement : [/B]This is a general conceptual doubt, not a numerical based doubt. We were taught that when an electron(or any charged particle) moving with uniform velocity enters a magnetic field(perpendicular to its direction of motion), then a force acts on the electron which makes it...
  10. Hydrous Caperilla

    Location of electrons and protons

    Homework Statement a proton and an electron initially at rest ,combined to form a hydrogen atom in ground state.A single photon is emitted in this process.The wavelength of the emitted photon is Homework Equations E=hc/ λ The Attempt at a Solution e So I know when the system is formed the...
  11. F

    Is the Rydberg formula true for electron absorption only?

    Since we know that when an electron goes from the ground state (hydrogen) n=1 to n=3 for example, we have ΔE = E3 - E1 by manipulating the equation we get Rydberg's formula 1/λ= R (1/ni2 - 1/nf2) (where R is Rydberg's constant) My question here, if the electron goes from higher energy state...
  12. H

    B Some website about new Bohr model

    This website <link removed> by some Japanese guy talks about a new Bohr model that can accurately calculate energy of Helium and other noble gases, as well as bonds, in non-relativistic level. (I happened to come across this website when I was searching about spinor.) He also reviews why old...
  13. K

    I Bohr model, Why do we assume a standing wave?

    Hi, I wonder why we assume the matter wave of an electron is standing wave. Is there any reason why it has to be standing wave?Is it because standing wave is the right "wave equation solution" that satisfies integer multiple behaviour of bohr model?
  14. adamaero

    Bohr Model applied to Excitons

    An exciton is a bound electron-hole pair (in a semiconductor). For this problem, think of an exciton as a hydrogen-like atom, with a negatively charged electron and positively charged hole orbiting each other. The permittivity of free space (ε0) is replaced with permittivity of the...
  15. Vitani11

    How do you modify the Bohr model equation for Li++?

    Homework Statement Consider an electron in the n = 4 level of Li ++. According to the Bohr model, what is the radius of the orbit of the electron? Homework Equations r = .0529 nm r(n) = (.0529 nm) x (n2) The Attempt at a Solution I thought this was pretty obvious? We want to know the radius...
  16. K

    I Why the energy inversely propotional to n^2 in Bohr model

    After reading some materials on Bohr model, I understand the model is more or less incorrect, especially in terms of "orbital". I just wonder if the energy expression is also wrong or not. In my text for general quantum theory, the energy about two neighboring level is given as ##\Delta E =...
  17. G

    What is the Orbit of Hydrogen Atom for an Electron at 734 km/s?

    Homework Statement On which orbit of hydrogen atom an electron has the speed of 734 km/s? Homework Equations Bohr's second postulate: mvr=nh,m=9.109\cdot 10^{-31}kg,v=734 km/s,h=6.626\cdot 10^{-34} m^{2}kg/s The Attempt at a Solution By using the second Bohr's postulate, we get 6686.006\cdot...
  18. K

    Electrostatic Energy in the Hydrogen Atom

    Homework Statement We model the Hydrogen atom as a charge distribution in which the proton (a point charge) is surrounded by negative charge with the volume density of ρ = -ρ0 * exp (-2r/a0) where a0 is the Bohr radius. And ρ0 is a constant chosen such that the entire atomic distribution is...
  19. P

    Ionization Energy of Helium Atom | 24.6 eV

    Homework Statement The energy required to ionize a helium atom is 24.6 eV. The energy required to remove both the electrons from He atom would be?The Attempt at a Solution My textbook says- IP1= 24.6 eV IP 2= IP1*Z2 How can they relate the first ionization energy to the second one? The Bohr's...
  20. J

    Angular momentum of hydrogen atom with Schrodinger Equation

    If we were to assume that the electron moves around the proton with radius a, the Schrodinger equation becomes: ##\frac{1}{a^2}\frac{d^2\psi}{d\phi^2} + \frac{2m}{\hbar^2}|E|\psi = 0## The question in my textbook asks me to solve the above equation to obtain values of energy and angular...
  21. little neutrino

    Bohr's Correspondence Principle

    Homework Statement (a) Show that in the Bohr model, the frequency of revo-lution of an electron in its circular orbit around a stationary hydrogen nucleus is f = me4/4ε02n3h3 (b) In classical physics, the frequency of revolution of the electron is equal to the frequency of the radiation that it...
  22. epenguin

    Elements of truth - Moseley, Bohr, recognition and teaching.

    There is no longer a history section in PDF, but this is not suitable for any speciality forum. Just yesterday*, as usual a step ahead and with uncanny prescience, I was recommending a student to familiarise himself with Moseley's law as reinforcement and more in the learning of atomic physics...
  23. 1

    Calculate Bohr Radius of Hydrogen Atom (n=600)

    I'm doing a homework problem where it asks to calculate the diameter of a hydrogen atom with n=600. I used the equation $$r=\frac{n^2a_0}{Z}$$ where $$a_0=0.529e^{-10}m$$. Solving for r yields: $$r=\frac{(600^2)(0.529e^{-10}m)}{1}=1.90e^{-5}m$$ Multiplying by 2 to get the diameter yields...
  24. C

    Electric Potential and Ionization Energy of Bohr Hydrogen

    I was studying for (first year) physics class and was playing around with the Bohr Model of Hydrogen. I tried calculating the electric potential at the Bohr radius r =5.29e-11 m, where V = \frac{e}{4 \pi \epsilon_0 r} (from the point-charge formula for electric potential) and I got 27.19 J/C...
  25. M

    Does the Bohr model go against classical Electromagnetism

    I was told in high school that Rutherford's atomic model was wrong because an electron which is in acceleration must release energy. That's how electromagnetic waves are made. and then I was told that Bohr gave his model and solved this problem. By making energy quantized. But what I really...
  26. yeshuamo

    Kinetic energy of electron: Quantization of angular momentum

    Homework Statement Show that the quantization of angular momentum implies that the kinetic energy of the electron is quantized as K=nhforb/2, where forb is the frequency of rotation. Assume circular orbit. Homework Equations Radial acceleration: arad = v2/r = (4π2r/T = 2*π*v/Tr = nħ KE =...
  27. E

    Bohr model and relativistic electron mass

    From the semi-classical Bohr model of the hydrogen atom the velocity of the electron in a certain orbit can be determined. With these velocities the electron's relativistic masses can be determined. With E=mc2 the energy levels are in agreement with those from the Bohr model. I know Bohr's model...
  28. Rapier

    Quantum Theory of Earth Satellite Analogy to Bohr Model

    Problem: In analogy to the Bohr Theory of the hydrogen atom, develop a quantum theory of Earth satellites, obtaining expressions for the orbit radius (r) and the energy (E) in terms of the quantum number (n) and the other relevant parameters. A satellite of mass 1000 kg is in a circular orbit of...
  29. K

    Electron revolutions in Bohr model

    Homework Statement On the average, a hydrogen atom will exist in an excited state for about 10-8 s before making a transition to a lower energy state. About how many revolutions does an electron in the n = 2 state make in 10^-8 s? Homework Equations L = mvr = Iω = nħ rn = n2a0/Z The Attempt...
  30. J

    Understanding the Bohr Model and Electron Decay

    Hi, I'm really struggling to comprehend how the Bohr model solves the problem of accelerating electrons losing energy and decaying into the nucleus. I've read through a lot of discussions on line and on PF and all I keep on reading is stuff like, the quantization of energy levels leads to a...
  31. B

    Oscillation frequency of electrons in atoms (Bohr model)

    Homework Statement Here is a picture: http://puu.sh/bZtAu/82bdc201bc.png Homework Equations For force, F = (Ze^2)/4 * pi * e0 * R^3) * r f = sqrt(k/m) * 1/2pi Where e0 = vacuum permeability, 8.854 x 10^-12m and r = radius of hydrogen atom, 5.3 x 10^-11m The Attempt at a Solution I...
  32. Y

    Intro Quantum Mechanics: Neils Bohr Model Explained

    Recently, I saw a video on Introductory Quantum Mechanics. Here's the link : https://www.youtube.com/watch?v=5Gnqpbge3Yk I failed to understand the explanation of de Broglie's model. He mentions that the waves interfere with each other but how do we know the properties like amplitude etc. of...
  33. RJLiberator

    Bohr Model Problem (Part 2 - Updated)

    Greetings again, So I realize my last thread: https://www.physicsforums.com/showthread.php?t=757685 became chaotic with my thoughts and un-clear writing. I've re-did the work to make it easier for people to understand my thought process. The two questions are as follows: 7)Calculate the...
  34. RJLiberator

    Help with the Bohr Model Problem

    Okay, I am in need of some guidance: 7)Calculate the wavelength that corresponds to an emission of energy of 1.977x10^-19 J. Okay, well here is my thought process initially: Change in Energy = hc/wavelength. First question: Is 1.977*10^-19 THE change in energy? OR is that the Energy...
  35. 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...
  36. Z

    Electron energy levels in Bohr model

    Homework Statement At the bottom of this linked-to screen below is an equation for E = - ... = - .... = - 13.6 Z^2 / n^2 eV https://en.wikipedia.org/wiki/Bohr_model#Electron_energy_levelsHomework Equations I'm using the following values for the formula Z=1 n=1 K sub e = 8.987 x 10^9...
  37. G

    Bohr model and quantum model

    Please excuse for my less knowledge in the subject.But I have genuine inquisitiveness. My Question is: If we assume electrons traveling in the orbit around nucleus like planets by inverse square law then electron must always be in the plannar path i,e. never coming out of plane of motion.Then...
  38. L

    Finding n in Hydrogen Atom Excitation with Bohr Model

    Homework Statement A hydrogen atom in an excited state absorbs a photon of wavelength 410 nm. What were the initial and final states of the hydrogen atom. Homework Equations Rydberg equation: \frac{1}{λ}=R_∞(\frac{1}{n{_l}{^2}}-\frac{1}{n{_u}{^2}}) The Attempt at a Solution...
  39. H

    Bohr Model: Energy Jump in Hydrogen Atom

    Am I right in saying that in a Hydrogen atom when an electron jumps from the second orbit to the first one the energy change is more than any other possible jump (when the jump is not to the first orbit). The calculations seem to support me but it doesn't feel right.
  40. T

    Valid reason to reject the Bohr model?

    The Bohr model has been superseded by the Schrodinger model. The Bohr model involves electrons orbiting around a nucleus. I was thinking, it might be possible for the electrons to be knocked out of their stable orbits into some chaotic configuration. Is this a valid reason to reject the...
  41. S

    Calculating Energy in Helium Ion Ground State via Bohr Model

    Homework Statement Consider a helium ion with 2 neutrons and 2 protons in the nucleus and 1 bound electron. Use the Bohr model with corrections for charge and mass of the nucleus. Calculate the energy in the ground state. Homework Equations m*v*r = n*(h/2*pi) The Attempt at a...
  42. R

    Bohr model & relativity on large atoms?

    Why Doesn't the increase in mass of the electrons, due to the relativistic correction required to prevent the calculated electron speed exceeding the speed of light, increase the mass of the atoms of the large elements? If the electrons were heavier on larger elements then the mass would diverge...
  43. C

    Bohr model electron wavelengths

    Hi I know that in the Bohr model, electrons move between energy levels, but you don't hear much about the electron's wavelength at each particular level. If we assume the orbits contain an integer multiple of wavelengths, you get the usual $$2\pi r=n\lambda,$$ so, based on the expression for...
  44. S

    Rejecting the Semiclassical Bohr Model: Examining the Uncertainty Relation

    "Show that the uncertainty relation forces us to reject the semiclassical Bohr [...]" Homework Statement The problem along with the solution is attached as TheProblemAndSolution.jpg. Homework Equations Uncertainty principle/relation. The Attempt at a Solution Why is it the consideration of...
  45. A

    Helium atom and bohr model

    Homework Statement He+ ion consists of a nucleus which is an alpha particle plus one orbiting electron.Hence it has a net positive charge. a)Derive an expression for the electron state energies b)what is the wavelength associated with a transition between the lowest two energy states...
  46. M

    If the bohr model of the atom is correct

    so imagine a hyper-classical scenario. A single point elecrron is orbiting a point nucleus. No other charged objects are nearby. There is no em radiation from the electron. The electron orbits the nucleus in perfect circular motion. Zero orbital precession, zero uncertainty in the...
  47. D

    Bohr model question - transition between first excited state and ground state

    Homework Statement In a hydrogenlike ion with atomic number Z, the energies of the allowed states are given by E(n) = (-13.6eV) (Z^2/n^2) What is the wavelength asociated with the transition between first excited state and ground state of hydrogen-like helium? (He+) Homework...
  48. O

    Bohr Model and photon emission

    I am feeling a little stupid asking this considering I am about to graduate with my BS in chemistry. But I have never given this much thought, nor do I remember learning this and I can't figure out a proper explanation. I am sure I am overlooking a simple detail, but I can not figure it out...
  49. C

    Bohr Model of Atom: Stability Condition Explained

    Eisberg and Resnick says that the condition for stability of the atom is: k Ze2/r2=mv2/r What I fail to understand is why the Z isn't square too. I mean surely you have Z electrons interacting with Z protons which which would surely give q1q2=(Ze)(-Ze)=-Z2e2? What am I missing?