Motion of an electron

[Lizwi]

Why are electrons said to be moving in a circular motion, when the orbitals are not circular?

[druS]

You've got to be talking apples v oranges here.

Beta radiation which can be considered a beam of electrons has the electrons moving in a circular motion because the magnetic force occurs perpendicular to the direction of the charged particle. This creates a centripetal force(this is classical mechanics not modern theoretical physics) and the particle must move in a circular motion.

Which has nothing to do with orbital movement.

[StringJunky]

Bound electrons are seen as in a standing wave configuration, not actually moving. It's only when you measure them they become discrete.

http://hyperphysics.phy-astr.gsu.edu/hbase/ewav.html

 

Edited February 14, 2019 by StringJunky

[swansont]

The picture of circular motion of electrons stems from the Bohr model, which is obsolete, That view has been shown to be incorrect.

[studiot]

18 minutes ago, swansont said:

The picture of circular motion of electrons stems from the Bohr model, which is obsolete, That view has been shown to be incorrect.

It is also the easiest to model and talk about so most courses start from there to explain the ideas.

[Lizwi]

Thanks very much

[StringJunky]

1 hour ago, studiot said:

It is also the easiest to model and talk about so most courses start from there to explain the ideas.

Is it though. I remember being really annoyed when I went from O-level to A-level chem and was told the Bohr model was wrong. Why not just get stuck into the current theory and back track historically as required?

[swansont]

8 minutes ago, StringJunky said:

Is it though. I remember being really annoyed when I went from O-level to A-level chem and was told the Bohr model was wrong. Why not just get stuck into the current theory and back track historically as required?

Full-blown QM is a lot to handle, when all you've done is classical.

[StringJunky]

2 minutes ago, swansont said:

Full-blown QM is a lot to handle, when all you've done is classical.

I'm sure you're right but sometimes I think it's better not to know than learn something that's not correct.

[druS]

18 minutes ago, StringJunky said:

I'm sure you're right but sometimes I think it's better not to know than learn something that's not correct.

And sometimes things need to be handled at a conceptual level. TBF as someone going through education on these matters, they don't leave a starting student with the impression that the Bohr is "it". The Bohr model is certainly didactic, but we were firmly moved on to de Broglie (loose rough conceptual basis only).

SJ - the Educationists get better with each generation.

[StringJunky]

21 minutes ago, druS said:

And sometimes things need to be handled at a conceptual level. TBF as someone going through education on these matters, they don't leave a starting student with the impression that the Bohr is "it". The Bohr model is certainly didactic, but we were firmly moved on to de Broglie (loose rough conceptual basis only).

SJ - the Educationists get better with each generation.

Yeah, I'm going back 41 years.  

Edited February 14, 2019 by StringJunky

[studiot]

33 minutes ago, druS said:

And sometimes things need to be handled at a conceptual level. TBF as someone going through education on these matters, they don't leave a starting student with the impression that the Bohr is "it". The Bohr model is certainly didactic, but we were firmly moved on to de Broglie (loose rough conceptual basis only).

SJ - the Educationists get better with each generation.

The OP also asked about orbitals.

When I did my A level Chemistry in the 1960s, we started with Bohr orbits as this leads easily to atomic spectroscopy.
But we did move on to orbitals, where one has to leave Bohr behind so that we could look at bonding and molecular structure.

The modern A level is much weaker.

Atomic and molecular structure were not covered at all in the 1960s A level Physics and spectrocopy was something Newton did with prisms.
I can't say about today.

[MigL]

Also Bohr is much easier to handle mathematically.
You do need a good base in Calculus to handle QM.