Atomic Structure: Is It Necessary to Assume Orbits Are Circular?

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Discussion Overview

The discussion centers around the nature of electron orbits in atomic structure, specifically questioning whether it is necessary to assume that these orbits are circular. The scope includes conceptual understanding of atomic models, particularly the classical and quantum mechanical descriptions of atoms.

Discussion Character

  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • Some participants assert that the classical view of electrons revolving around the nucleus in circular orbits is not accurate, emphasizing that electrons are better described by their wavefunctions in a quantum mechanical framework.
  • Others mention that while the Bohr model provides useful insights, it is not fully accurate and assumes circular orbits for simplicity.
  • It is noted that electron wavefunctions can take various shapes, with some being spherically symmetric and others not, indicating that the assumption of circular orbits is not necessary.
  • One participant highlights that spherically symmetric orbitals correspond to cases where the electron has no angular momentum, suggesting that describing electron motion as 'orbiting' is misleading.
  • There is a suggestion that classical models, including the Bohr model, have deficiencies that prevent them from accurately describing atomic behavior.

Areas of Agreement / Disagreement

Participants generally agree that the classical model is insufficient for accurately describing atomic structure, but there is no consensus on the necessity of assuming circular orbits, as some find the Bohr model useful despite its limitations.

Contextual Notes

The discussion reflects limitations in classical models and the complexities of quantum mechanics, with unresolved questions about the implications of different orbital shapes and their physical interpretations.

Tush
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Please help me in clearing my basic doubt

We all know that positive charges are concentrated at the centre of the atom , known as nucleus and electrons revolves around the nucleus in orbits. Is it necessary to assume that orbits are circular ?
 
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Tush said:
Please help me in clearing my basic doubt

We all know that positive charges are concentrated at the centre of the atom , known as nucleus and electrons revolves around the nucleus in orbits. Is it necessary to assume that orbits are circular ?

Be careful. A classical picture of "electrons revolv[ing] around the nucleus in orbits" is not correct in a literal sense. An atom is a quantum mechanical system, and the electrons can only be described by their wavefunction, rather than a well-defined trajectory.

With that said, one needs to make no assumptions about the shape of these wavefunctions. They can be calculated. Some of them are spherically symmetric (the probability of finding that electron only depends on the distance from the nucleus), but others are not.
 
Note also, that the quantum mechanical description of the atom is probably something that is accessible at the college level. Until you have reached the necessary level of preparation, there is always the Bohr model, which provides several useful insights and conveys many of the key characteristics of the quantum mechanical description, but is not quite as accurate as it. Within the Bohr model of the atom, the nucleus is considered to be a heavy positively charged point at the center of the atom, and negatively charged point-like electrons revolve around the nucleus in circular orbits.
 
short answer: no. but it has some usefulness as noted.

Try reading the Wikipedia introductions for "electron orbital" ...both atomic and molecular...
you might also try reading Wikipedia about 'electrical conductors'...where conuction electrons move along a conductor as in a current carrying copper wire.
 
the_house said:
Some of them are spherically symmetric (the probability of finding that electron only depends on the distance from the nucleus), but others are not.

Right. It also happens that the ones which are spherically symmetric (s-orbitals) correspond to cases where the electron has no angular momentum. So if you were to attempt to describe the motion classically (bearing in mind that they don't actually have trajectories) it'd be more correct to say the electrons are moving 'inwards and outwards' from the nucleus, rather than 'orbiting' it.

This is part of the reason why classical/semiclassical models of the atom ultimately can't work; because there's no way that something moving as a classical particle can have a spherically symmetrical pattern of motion without having any angular momentum. (this is only one of several deficiencies of the Bohr model)
 

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