Why are electrons never in between orbitals?

Quantum hats on! This week's 'exciting' question is about particle physics.....
16 April 2021
Presented by Phil Sansom
Production by Phil Sansom.

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Quantum hats on for this week's 'exciting' question! Listener Mejnun says: "I have learned at school that when an electron excites it jumps to another orbital around the nucleus. If an electron jumps an orbital you would expect that at that moment it can be found between the two orbitals. My teacher told me that this is never the case. I can not wrap my head around it. Does the particle just disappear in one orbital and appear in the other? Is this instant, is the particle in the other orbital the same? Can you please help me to understand this?" Phil Sansom asked physicist Ankita Anirban to tackle the problem...

In this episode

An atom graphic coloured with a rainbow gradient

QotW: Why are electrons never between orbitals?

Phil Sansom got the answer from Ankita Anirban...

Mejnun - I have learned at school that when an electron excites it jumps to another orbital around the nucleus.

Phil - Remember, electrons are tiny particles, and they move in patterns called ‘orbitals’.

Mejnun - If an electron jumps an orbital you would expect that at that moment it can be found between the two orbitals. My teacher told me that this is never the case. I can not wrap my head around it. Does the particle just disappear in one orbital and appear in the other? Is this instant, is the particle in the other orbital the same? Can you please help me to understand this?

Phil - Mejnun, don’t worry, you came to the right place. Here’s physicist Ankita Anirban...

Ankita - Hi Mejnun!

Phil - She's here to answer what happens when electrons jump to a new orbital.

Ankita - From what you’ve said, it seems to me like you’re imagining orbitals as concentric rings around the nucleus. This is a useful model, but all models are just approximations. And you’ve found the fatal flaw of this model! As soon as you ask - is the electron sometimes between orbitals, there is no good answer. A more accurate way of understanding electrons is through quantum mechanics.

Quantum mechanics is a theory that explains how particles like electrons work, and it's all about probabilities - so when we say an electron is in a certain orbital, it just means that it is quite likely to be in that general area. And if we excite the electron, it just means that the likelihood of finding it in the outer orbital increases. So rather than thinking of an electron physically jumping between orbitals, you can imagine the chances of finding an electron in a given orbital changing.

This might seem quite abstract, but according to quantum mechanics, an electron isn’t actually a tiny billiard ball, hopping between orbitals.  A better way of thinking about it is more like a little fuzz of mass and energy that is very hard to pin down. But again, this is still just a model which also has limitations.

Phil - Here’s another comparison, from our forum: chiralSPO says to think of the electron as a wasp. It can be calm, or it can be angry. There is nothing in between, and it can instantly go from one to the other or back. Again, just a metaphor for something extremely complicated!

Ankita - Even though I’m a physicist who deals with electrons daily, trying to actually imagine an electron has sent me down a philosophical rabbit hole!

Phil - Thanks to Ankita for diving in for us. Meanwhile our next question comes from listener Ellie, has been pointing, and clicking, and then wondering...

Ellie - How do ZIP files work on my computer?

 

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