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. J

    Electromagnetic radiations in bohr model

    Bohr model had a flaw that electrons would emit EM radiations and would spiral into the nucleus - but he just said that it wouldn't happen providing no reasons Do the modern models of atom explain - why electrons won't emit EM radiations?
  2. A

    How did the Bohr Model improve the Quantum Mechanical Model?

    Homework Statement How did the Bohr Model improve the Quantum Mechanical Model on our knowledge of electrons? Homework Equations The Attempt at a Solution So far I have that the quantum mechanical model of the atom restricts the energy of the electrons to certain values called...
  3. W

    Bohr Model Equations: Kinetic and Potential Energy in Hydrogen Atom

    Homework Statement Write an expression relating the kinetic energy KE of the electron and the potential energy PE in the Bohr model of the hydrogen atom. (Use any variable or symbol stated above as necessary.) b) Suppose a hydrogen atom absorbs a photon of energy E, resulting in the...
  4. C

    Exploring the Bohr Model: Visible Light Transitions in Li++

    Bohr Model [b]1. Assuming that the wavelengths of visible light lie between about 300nm and 700nm, what transitions in Li++ (hydrogenic lithium ions, Z=3) would be visible. Identify each transition by initial and final principal quantum number n. Also identify those transitions that are also...
  5. P

    Bohr Model and wave-particle duality

    I am currently studying wave-particle duality. However, at the moment I do not see how the Bohr Model is connected to this topic. I know that the Bohr Model failed to recognise various aspects of the atom and that it works only for single atoms e.g. Hydrogen, but what did it fail to do when it...
  6. G

    Landau levels and bohr model

    hi i thought that if i try to derive the energy of an electron in a magnetic field, this could be done with the assumptions of the bohr model. L=n h/(2π) mv²/r=qvB => mvr=qBr²=>n h/(2π)=qBr² E=p²/(2m)=q²B²r²/(2m)=n h/(2π)qB/(2m) so i get the energy for the first level, but all transitions...
  7. J

    Need Help Understanding Bohr Model Equations

    Bohr incorporates Plancks's quantum theory into his model, placing conditions on the value of the angular momentum. angular momentum = nh/2pi n=principal quantum number h= Planck's constant since its giving me the angular momentum, is it actually giving me a number that corresponds to...
  8. J

    The Bohr Model -answer one ? if not all

    hello, i am studying chemistry. There are a lot of things i do not understand though. This is not homework, just studies of my own that i would like to reach a deeper understand of. I love the responses i have read, so decided to make an account and learn from all you geniuses! Bohr model...
  9. A

    Reevaluating the Bohr Model of the Atom and Its Radiation Emission

    I think a problem with the bohr model of the atom was that if the electron was in orbit around the nucleus, it would keep emitting radiation of longer and longer wavelengths until it falls into nucleus. Why does an electron in orbit necessarily have to emit radiation?
  10. A

    Bohr model find orbital radius for electron

    Homework Statement In the Bohr model, the electron is imagined to move in a circular orbit about a stationary proton. If the speed of the electron were 8.9e5 m/s, what would be the corresponding orbital radius? Homework Equations The Attempt at a SolutionFe=ma Fe=ma a=Fe/m (v^2)/r=(kqq/r)/m...
  11. L

    Understanding Orbitals and Energy Levels in the Bohr Model

    I'm sitting with Physics Handbook and I'm trying to recall how the make out the orbitals in the energy levels. Let's take a look at the first levels. n = 1 - sub-shell K Number of electrons = 2n^2 \Rightarrow 2 electrons. Number of electrons = l = 0,1... n-1 \Rightarrow l = 0. This is where I...
  12. R

    Bohr Model Vs. Shrodingers Mech. wave model

    Homework Statement In Chemistry class i was assigned a essay. This essay was comparing and contrasting the mechanical wave model to Bohrs model of an atom. some things i have now are Bohrs -Unreliable for finding electrons in orbits -Dense core with protons - Shrodingers -ability to predict...
  13. fluidistic

    Modern physics, Bohr model of atom

    Homework Statement According to Bohr's atomic model, 1)Determine the allowed radius of the orbit of the electrons. Calculate the radius of the first orbit for the hydrogen atom. 2)Show that the energy of the electron is quantized. Calculate the energy corresponding to an electron on the first...
  14. A

    About The Bohr Model of the Hydrogen Atom

    Homework Statement What energy (in eV) is required to remove the remaining electron from a singly ionized helium atom, He+ (Z = 2)? (a) 3.40 eV (c) 27.2 eV (e) 76.9 eV (b) 13.6 eV (d) 54.4 eV Homework Equations Ei - Ef = hf The Attempt at a Solution Ef: the 1st level Ei...
  15. D

    Bohr Model in Polar Co-ordinates

    The angular momentum of the Bohr atom is ⃗L = ⃗r× ⃗p Let the Oz axis of the unit vector ⃗uz be determined by the relation L = L⃗uz, in which L stands for the magnitude of the angular momentum vector ⃗L . (Basically L is in Positive z axis) We specify the position of the electron within its...
  16. M

    Bohr Model Electron Movement Question

    Homework Statement How does an electron get from an excited state (r = 4ao) to a ground state (r = ao) without being anywhere in between? Homework Equations The Attempt at a Solution My only attempt would be to say that it does exist between for a short time, and during that time it emits a...
  17. Shackleford

    The Bohr Model of the Hydrogen Atom

    A hydrogen atom in an excited state absorbs a photon of wavelength 434 nm. What were the initial and final states of the hydrogen atom? E = hf = Eu - El = 2.825 eV That's the difference in energy between the initial and final states.
  18. J

    Classical Physics and the Bohr Model of Hydrogen Atom

    Homework Statement Classical physics applied to the bohr model of the hydrogen atom would predict that light could be emitted continuously, rather than in discrete chunks of energy. Transitions between what kinds of energy levels would come close to the classical viewpoint? A. Only levels...
  19. N

    Bohr Model (Lyman,Balmer,Paschen series)

    Homework Statement Determine the wavelengths of photons given off for the 3rd line in the Lyman series , the 2nd line in the Balmer series, and the 1st line in the Paschen series. The question is weird, I don't understand what the "line" mean... "1st line in the Paschen series " Is it mean ni...
  20. J

    Calculating Electric Force in Bohr Model of Hydrogen Atom

    Homework Statement In the Bohr model of a hydrogen atom, what is the magnitude of the electric force exerted between the proton and the electron when the electron is in the n = 1 state? Homework Equations E= - 13.6 eV/ n^2 The Attempt at a Solution I simply...
  21. P

    Can the Bohr Model really prevent electron energy loss?

    Even though Bohr's model is defunct, one important element of it survived, namely the strictly quantized orbiting radii of electrons. Supposedly this mended the gaping flaw of Rutherford's model in that it predicted that electrons would no longer lose energy to photon emission thereby causing...
  22. M

    Bohr model hydrogen potential energy

    Homework Statement How do you find the potential energy of the hydrogen atom in n=11 state using Bohr model? express in eV Homework Equations I used U= -kZe^2/r The Attempt at a Solution =-8.99e9(1.6e-19)^2/5.29e^-11 =4.35e^-18J / 1.6e^-19 =-27.2eV
  23. K

    Quantum mechanics replacing bohr model

    do all of the electrons in an atom have to move up or down an energy level or is it just the valence electrons or what? is there one photon released per electron and are they all the same wavelength?
  24. R

    Calculate Potential Energy of Electron in Bohr Model

    How can I calculate the potential energy of the electron when we bring it from the infinity to the distance r?
  25. G

    Exploring the Bohr Model: Allowed Radii, Kinetic & Electric Potential Energy

    Homework Statement The Bohr model The Bohr model correctly predicts the main energy levels not only for atomic hydrogen but also for other "one-electron" atoms where all but one of the atomic electrons has been moved, as as in He+ (one electron removed) or Li++ (two electrons removed). To...
  26. V

    Speed of electron in Bohr model

    Homework Statement In the classical Bohr model of the hydrogen atom, the nucleus has one positive electronic charge Q_n = e = +1.602E-19 Coulombs and the single electron (mass = 9.1E-31 kg and Q_e = -e = -1.602E-19 C, one negative electronic charge) orbits the nucleus in a circular orbit. In...
  27. M

    Quantization using the bohr model

    bohr model: permitted radii? Homework Statement A new (fifth) force has been proposed that binds an object to a central body through a potential energy function given by: U(r) = -Dr^{\frac{-3}{2}} 2 r > 0 and D > 0 (a) What is the (central) force F(r) associated with this potential...
  28. O

    How Does the Bohr Model Explain Energy Levels in One-Electron Atoms?

    Homework Statement The Bohr model The Bohr model correctly predicts the main energy levels not only for atomic hydrogen but also for other "one-electron" atoms where all but one of the atomic electrons has been moved, as as in He+ (one electron removed) or Li++ (two electrons removed). To...
  29. B

    Earth's Quantized Angular Momentum and Energy Transition in the Bohr Model?

    Homework Statement 4-16: if the angular momentum of the Earth in its motion around the sun were quantized like a hydrogen electron according to equation L=mvr=(nh)/2Π, what would Earth's quantum number be? How much energy would be released in a transition to the next lowest level? would...
  30. F

    Calc K-Shell X-Ray Series Wavelengths for Zirconium Atom

    Calculate the three longest wavelengths and the series limit for the K-shell x-ray series of the zirconium atom. (a) λ(Kα) = 79.8832 pm (b) λ(Kβ) = 67.401142 pm (c) λ(Kγ) = 63.90653 pm (d) The series limit is _____ pm So I have solved parts a-c. For part d, the series limit, I tried...
  31. M

    Understand the Bohr Model of H-Atom's 1s2p Splitting

    [SOLVED] Bohr Model of H-atom Hi, Would anyone be good enough to explain why the 1s2p splitting in a hydrogen atom is 3/4 of the total binding energy? Would it have anything to do with the Rydberg energy? E = - 13.6eV/n^2 I appear to have floated through my degree blissfully...
  32. M

    Is the Bohr model of the atom still valid in quantum mechanics?

    Why does in QM the electron does not fall toward the nucleus? After all, the only force between nucleus and electron is attractive (- electron and + nucleus). Is the same reason that justifies the moon does not fall to the earth?
  33. 8

    How Does the Uncertainty Principle Invalidate the Bohr Model?

    Why the uncertainly relation ΔxΔp>h forces us to reject the semiclassical Bohr model for the hydrogen atom?
  34. hagopbul

    Exploring Atom's Mysteries: Bohr Model & Quantum Theory

    Atom But? I am studying atom and I reach the Bohr model & the quantum theory of atom for now. But I have some point that I don’t understand for example: 1st We assume that the positive charge (protons) and 99% of the mass (neutrons) are stable, (in most cases), in the center of the atom .And...
  35. B

    Calculating Hydrogen Bohr Orbit Transition and Series using Wavelength 410.7 nm

    Homework Statement Light of wavelength 410.7 nm is observed in emission from a hydrogen source. a) what transition between hydrogen bohr orbits is responsible for this radiation? b) to what series does this transition belong to? Homework Equations1/lambda=Z^2 *R(1/n^2-m^2) , n being the...
  36. M

    Niels Bohr Model: Exploring Hydrogen Orbits

    Hi, we know that we can find the radius and energy of the orbits of hydrogen.now why is it so that we cannot apply the same formulas for other elements by using the equations given by bohr.if there are complications what are they?
  37. I

    Bohr Model missing momentum question

    In the Bohr atomic model, electrons move between shells having angular momentum L_n = n h_bar where n is the shell number and the difference in shell energies E_n2-E_n1 matches the Rydberg energy of the emitted or absorbed photon. My question is: what hapened to the angular momentum...
  38. P

    A few questions about the Bohr model

    I was just doing some last minute review for my physics final tomorrow, and I have a few question about the Bohr model of the Hydrogen atom. 1) So at the ground state, a bound electron has -13.6eV energy. Now, say there was a photon with 14eV fired at it... would the electron escape? I mean...
  39. F

    The Bohr Model of the Hydrogen Atom

    The electron in a hydrogen atom is in the first excited state, when the electron acquires an additional 2.86 eV of energy. What is the quantum number n of the state into which the electron moves? I found the answer to be 5 but I don't know how. I thought I could use the following equation...
  40. T

    Bohr Model: Calculating Wavelengths of Emitted Photons

    Hi, I'm having trouble on the following question: A singly ionized helium atom is in the ground state. It absorbs energy and makes a transition to the n = 3 excited state. The ion returns to the ground state by emitting two photons. What are the wavelengths of the lowest energy photon and...
  41. N

    Bohr Model / Energy question

    Q: From the Bohr model of the Hydrogen atom, calculate the minimum amount of energy (in eV) an electron in the lowest orbital would need to free it from its proton (i.e., to ionize the atom). A: would I use the equation: En = - 13.6 / (n^2) ? If so, an an electron in its ground state would...
  42. Y

    Does Bohr Model Contradict Classical Physics?

    a question asks if the Bohr model contredicts in any way classical physics. i replied that only the first assumption that the electrons are fixed in circular orbits violates the laws of classical mechanics - of the idea of centripetal acceleration (?) am i right to say that? did i miss...
  43. V

    Quantised Energy Levels - Bohr model

    Hi Guys, Because of the absorbtion and emmision spectrum we know that atoms have quantised engergy levels. For example for an electron to jump from ground state to the first excited state in a Mecury atom, a photon with the exact energy of 4.9eV is required. Now my question is what would...
  44. J

    Solving the Bohr Model of Atom: Transition from n=7 to n=5

    Hi; Could someone please help me with this question: By what fraction does the mass of an H atom decrease when it makes an n=7 to n=5 transition? How would I go about this question? Thank you.
  45. M

    The Bohr model of the H atom for anyone who needs it

    hey everyone! good morning! i just took like 15 minutes drawing this to ask a question, but the funny thing is that my question got answered as i was about to post this! :biggrin: :biggrin: so I'm leaving this up for anyone who wanted to look at it! Take care and enjoy! :cool: Note...
  46. J

    Revolutions in a Bohr Model

    According to the Bohr theory, how many revolutions will an electron make in the first excited state of hydrogen if the lifetime in that state is 10^-8? Basically do I find the speed of the that the electron moves in this excited state then get the distance that a revolution is and divide it...
  47. G

    Exploring Physics: Unveiling the Bohr Model

    I am currently taking Physics 30 now and we have just finished the Magnetism unit. The last little bit that we had to learn in the unit was about Albert Einstein's Theory of Relativity. I was just thinking about this...and maybe I'm crazy, but I'll just state my opinion. I was just thinking...
  48. M

    Explaining Acceleration of Electron in Bohr Model

    I keep reading that the Bohr model explained why the electron in orbit around the nucleus does not emit radiation even though it is accelerating. How does the Bohr model explain this?
  49. Q

    Dynamics of uniform circular motion and bohr model

    In the Bohr model of the hydrogen atom, an electron (mass m = 9.1 x 10^-31 kg) orbits a proton at a distance of 5.3 x 10^-11 m. The proton pulls on the electron with an electric force of 9.2 x 10^-8 N. How many revolutions per second does the electron make? can someone help me solve this...
  50. frankR

    Quantized angular momentum of diatomic gas molecule: Bohr Model

    Here is the problem: A diatomic gas molecule consists of two atoms of mass m separated by a fixed distance d rotating about an axis as shown. Assuming that its angular momentum is quantized just as in the Bohr atom, determine a) the quantized angular speed, b) the quantized rotational energy...
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