6

Sometimes we say that electron has volume, as in orbital we can define it's volume (at least for some fraction, as orbital itself has no limit, it is spread all over the space expect nodes).

On other hand in general chemistry books often spin quantum no. is referred as electron spinning on its axis. But this is absurd, because this magnetic angular momentum is an intrinsic property of the electron. Also that an electron is an elementary particle, it is 1-D (no volume), so it's not possible for an electron to spin on it's own axis.

So what's the matter, do electron has volume or not?

What I think that it's a particle, but we can't describe it's position what we can do is probabilistic approach, we can only describe some region where we can find it more likely or less likely. We defined it's volume, otherwise electron themselves has no volume. Even it is more weird that electron is everywhere in the orbital ;D

Can somebody explain it?

Mithoron
  • 4,546
  • 14
  • 40
  • 61
Aditya Shrivastava
  • 1,186
  • 12
  • 29
  • So far, in the standard quantum physics, electron is treated as a point-like particle. – user26143 Nov 27 '16 at 10:56
  • 1
    Spin has properties of regular angular momentum, but it is not. That is usually the first thing you are told when it is introduced in class. – Karl Nov 27 '16 at 11:58
  • 1
    Related question on Physics.SE - (http://physics.stackexchange.com/questions/24001/what-is-the-mass-density-distribution-of-an-electron) – Apoorv Potnis Nov 27 '16 at 12:22
  • @Karl but the electron can have regular angular momentum, too... – Greg Nov 27 '16 at 13:36
  • @Greg The orbital angular momentum is also a quantum mechanical entity. And if the electron is flying in a synchrotron, then it has of course regular, non-quantum mechanical angular momentum, but so what? It doesn't need a volume for that. – Karl Nov 27 '16 at 17:40
  • related http://chemistry.stackexchange.com/questions/62009/do-electrons-in-an-atom-revolve-around-the-the-nucleus-clockwise-or-counterclock/62054#62054 – Mithoron Nov 27 '16 at 19:15
  • @Karl No one was talking about synchrotrons. L has non-zero expectation value for many electronic states. – Greg Nov 30 '16 at 12:09
  • 5
    Does this answer your question? Do electrons have some volume, area or shape? – MCCCS Sep 08 '20 at 17:37

2 Answers2

7

If volume is understood classically, i.e. as the quantity of three-dimensional space enclosed by a closed surface, then quantum systems in general do not have a certain volume. One could, in principle, redefine the notion of volume for a quantum system to be, say, an area chosen so that there is a certain probability (for example, 90%) of finding the system within it, but that would be a completely different quantity, of course. It should also be noted that in quantum theory statements about a system having or possessing certain values of physical quantities has a lot of issues, even when the quantities are well defined. For instance, does a quantum system have (possess) certain values for physical quantities before the corresponding measurements are made?

On other hand In general Chemistry books often spin quantum no. is referred as electron spinning on its axis.

You already know that such picture is an absurd, and you are perfectly right here: electrons are not spinning. So there is no any contradiction there: they don't have a classical volume and they are not spinning.

Wildcat
  • 19,049
  • 2
  • 77
  • 107
  • What I know, any quantity has multiple defined values of physical quantities, can be shown as of if it has its own space. Eg. Momentum space. It can attain any of the value from its quantized space. – Aditya Shrivastava Sep 12 '20 at 01:55
3

An Orbital is not the volume of an electron. An orbital is the volume in space where the probability to find a certain electron is 99%. The electron itself is treated as this probability density in QC, and as a point charge when considered a definite particle.

In reality, an electron probably has a volume (since it has a mass, sometimes). In reality, there are no "orbitals" either...

On the other hand, particle-wave-duality...

And the concept of volume for electrons doesn't fit with Einsteins theory of relativity.

Well the world of quantum mechanics is complicated...

  • "In reality, there are no "orbitals" either..." What do you mean by that? – Mockingbird Oct 16 '17 at 00:04
  • @Mockingbird an orbital is a mathematical concept describing a volume where the probability to find an electron is 99.99%. The fact that there are different localizations of orbitals which "look" extremely different is also a hint that orbitals might not be a "real" object. –  Oct 16 '17 at 09:49