Difference Between Bohr and Quantum Modelwww.differencebetween.comKey Difference - Bohr vs Quantum ModelThe Bohr model and quantum model are models that explain the structure ofan atom. Bohr model is also called Rutherford-Bohr model because it is amodification of the Rutherford model. Bohr model was proposed by Niels Bohrin 1915. Quantum model is the modern model of an atom. The key differencebetween Bohr and quantum model is that Bohr model states that electronsbehave as particles whereas quantum model explains that the electron hasboth particle and wave behavior.What is Bohr Model?As mentioned above, the Bohr model is a modification of the Rutherford modelsince the Bohr model explains the structure of the atom as composed of anucleus surrounded by electrons. But Bohr model is more advanced than theRutherford model because it says that, the electrons are always traveling inspecific shells or orbits around the nucleus. This also states that these shellshave different energies and are spherical in shape. That was suggested byobservations of the line spectra for the hydrogen atom.Due to the presence of discrete lines in the line spectra, Bohr stated that theorbitals of an atom have fixed energies and electrons can jump from one energylevel to the other emitting or absorbing energy, resulting in a line in the linespectra.Main Postulates of Bohr Model The electrons move around the nucleus in spherical orbitals which have afixed size and energy.Each orbit has a different radius and is named from nucleus to the outsideas n 1, 2, 3, etc. or n K, L, M, etc. where n is the fixed energy levelnumber.The energy of an orbital is related to its size.The smallest orbit has the lowest energy. The atom is completely stablewhen electrons are in the lowest energy level.When an electron is moving in a certain orbital, the energy of thatelectron is constant.
Electrons can move from one energy level to another by absorbing orreleasing energy.This movement causes radiation.Bohr model perfectly fit the hydrogen atom which has a single electron and asmall positively charged nucleus. Apart from that, Bohr used the Plank’sconstant to calculate the energy of the energy levels of the atom.Figure 01: The Bohr Model for HydrogenBut there were few drawbacks of Bohr model when explaining the atomicstructure of atoms other than Hydrogen.Limitations of Bohr Model The Bohr model could not explain the Zeeman effect (effect of magneticfield on the atomic spectrum).It could not explain the Stark effect (effect of electric field on the atomicspectrum).Bohr model fails to explain the atomic spectra of larger atoms.What is Quantum Model?Although the quantum model is much harder to understand than Bohr model, itaccurately explains the observations regarding the large or complex atoms. Thisquantum model is based on quantum theory. According to quantum theory, anelectron has particle-wave duality and it is impossible to locate the exact
position of the electron (uncertainty principle). Thus this model is mainly basedon the probability of an electron to be located anywhere in the orbital. It alsostates that the orbitals are not always spherical. The orbitals have particularshapes for different energy levels and are 3D structures.According to the quantum model, an electron can be given a name with the useof quantum numbers. Four types of quantum numbers are used in this; Principle quantum number, nAngular momentum quantum number, IMagnetic quantum number, mlSpin quantum number, msThe principle quantum number explains the average distance of the orbital fromthe nucleus and the energy level. The angular momentum quantum numberexplains the shape of the orbital. The magnetic quantum number describes theorientation of orbitals in the space. The spin quantum number gives the spinningof an electron in a magnetic field and the wave characteristics of the electron.Figure 2: Spatial structure of atomic orbitals.
What is the difference between Bohr and Quantum Model?Bohr vs Quantum ModelBohr model is an atomic modelproposed by Niels Bohr (in 1915)to explain the structure of an atom.Quantum model is an atomic model whichis considered as the modern atomic modelto explain the structure of an atomaccurately.Behavior of ElectronsThe Bohr model explains theQuantum model explains the wave-particleparticle behavior of an electron.duality of an electron.ApplicationsBohr model can be applied forQuantum model can be used for any atom,hydrogen atom but not for largeincluding smaller ones and large, complexatoms.atoms.Shape of OrbitalsBohr model does not describe theQuantum model describes the all possibleexact shapes of every orbital.shapes an orbital can have.Electro-Magnetic EffectsBohr model does not explain theQuantum model explains the Zeeman andZeeman Effect (effect of magneticStark effects precisely.field) or Stark effect (effect ofelectric field).Quantum NumbersBohr model does not describe theQuantum model describes all fourquantum numbers other than thequantum numbers and the characteristics ofprinciple quantum number.an electron.Summary - Bohr and Quantum ModelAlthough several different atomic models were proposed by scientists, the mostnotable models were Bohr model and quantum model. These two models areclosely related but the quantum model is much more detailed than Bohr model.According to the Bohr model, an electron behaves as a particle whereasquantum model explains that the electron has both particle and wave behavior.This is the main difference between Bohr and quantum model.References:
1. "Bohr Model of an Atom Schrodinger atomic theory." Chemistry. Byjus Classes, 08 Nov. 2016.Web. Available here. 05 June 2017.2. "Atomic Structure: The Quantum Mechanical Model." Dummies. N.p., n.d. Web. Available here. 05 June2017.Image Courtesy:1. "Bohr model Balmer 32" (CC BY-SA 3.0) via Commons Wikimedia2. "Atom clipart violet" (Public Domain) via Commons WikimediaHow to Cite this Article?APA: Difference Between Bohr and Quantum Model. (2017, June 09).Retrieved (date), from nbohr-and-vs-quantum-model/MLA: "Difference Between Bohr and Quantum Model." DifferenceBetween.Com. 09 June 2017. Web.Chicago: " Difference Between Bohr and Quantum Model." DifferenceBetween.Com. n-bohrand-vs-quantum-model/ (accessed [date]).Copyright 2010-2017 Difference Between. All rights reserved.
According to the quantum model, an electron can be given a name with the use of quantum numbers. Four types of quantum numbers are used in this; Principle quantum number, n Angular momentum quantum number, I Magnetic quantum number, m l Spin quantum number, m s The principle quantum