Understanding Quantum Numbers and Orbitals: Tips for Effective Learning

[Docscientist]

In quantum mechanics,the facts about orbitals,sub shells and nodes are all confusing.I am not able to differentiate between them and I can't imagine them.This makes my whole process of learning about quantum numbers and filling up of orbitals very uncomfortable.Can somebody explain it to me so that I get it?
Suggestions to improve my way of learning quantum mechanics is also welcome.

 

[Simon Bridge]

Think of the electrons as being a cloud of charge rather than as a point particle.
Your text should show you the shapes of the clouds based on the 95% probability surface.
The quantum numbers should be thought of as abstract labels... like the dewey decimal system for finding books in a library.

 

[Docscientist]

Think of the electrons as being a cloud of charge rather than as a point particle.
Your text should show you the shapes of the clouds based on the 95% probability surface.
The quantum numbers should be thought of as abstract labels... like the dewey decimal system for finding books in a library.

How do I differentiate between orbitals and subshells when I visualise it ?

 

[Borek]

How do I differentiate between orbitals and subshells when I visualise it ?

Problem is, we use "orbital" very loosely and it means different things in different contexts. Assume orbital to be the smallest "box" containing two electrons, and be ready to be surprised by the fact others will use "orbital" in other meanings.

In general, at the beginners level QM is just a matter of learning some rules (without knowing where do they come from) and applying them. Learn them, do as many problems as you can find - there is no better way of learning.

 

[Docscientist]

Learning some rules (without knowing where do they come from) .

That is my greatest problem.In Schroedinger's equation,there are new signs that I have never seen before.They relate the square of "psi" sign with the number of orbitals.And I have no Idea how that works.I search every where in YouTube,Internet etc...and I don't get a satisfying answer.So I've just decided to leave this part of "quantum mechanics" for the teacher to teach and move on to the next chapter.Besides,without even having a clear knowledge of how stuff works and why it is the way it is,it becomes very difficult to do problems relating to it because you keep wondering whatever the hell you are supposed to do.

 

[Borek]

without even having a clear knowledge of how stuff works and why it is the way it is,it becomes very difficult to do problems relating to it because you keep wondering whatever the hell you are supposed to do.

You don't have to know where the rule comes from to be able to correctly apply it. If you have problems, it is not because you miss QM background.

 

[DrDu]

Theoretical chemists complain that it would be better to actually teach chemistry in beginners chemistry classes instead of fairy tales about orbitals which not only is incomprehensible to the students lacking the necessary mathematics and physics but often blatantly wrong.

 

[Docscientist]

Theoretical chemists complain that it would be better to actually teach chemistry in beginners chemistry classes instead of fairy tales about orbitals which not only is incomprehensible to the students lacking the necessary mathematics and physics but often blatantly wrong.

Can you be more precise about what you mean to say ?

 

[Kevin McHugh]

I don't understand what Dr Dru means. I had no problem visualizing orbitals in Gen Chem. The textbooks do an excellent job of graphic representation for the probability distributions. The only leap is to imagine the higher S, P or D orbitals surrounding the lower order n orbitals. Then the imagination starts to get a fuzzy picture.

 

[DrDu]

Can you be more precise about what you mean to say ?

Exactly to what you are complaining about. You got the right intuition that to understand what an orbital really is you have to be able to solve the Schroedinger equation and understand quantum mechanics. But you are lacking the necessary mathematics to do so.

 

[Docscientist]

I had no problem visualizing orbitals in Gen Chem.

How exactly did you visualise the new quantum model of atom?.I am able to visualise the orbitals but When it comes to subshells,I find it difficult to get a clear picture of it.

 

[Docscientist]

Exactly to what you are complaining about. You got the right intuition that to understand what an orbital really is you have to be able to solve the Schroedinger equation and understand quantum mechanics. But you are lacking the necessary mathematics to do so.

What is the required math to solve the equation ?
I think I can try to learn it step by step.

 

[DrDu]

Best get some decent book on quantum chemistry, e.g. Ira Levine, Quantum Chemistry.

 

[Kevin McHugh]

Remember one thing. The Schroedinger equation has an exact solution for the hydrogen atom only. One proton, one electron. Depending, all the energy states are allowed to the electron, so it can occupy S, P D, F orbitals, all the way up to ionization. It can have any allowed angular momentum.

It seems to me you are confusing quantum mechanics with VSEPR, which shows ground state electronic configurations for many electron elements.

 

[Kevin McHugh]

http://chemistry.stackexchange.com/questions/18466/difference-between-shells-subshells-and-orbitals

Maybe this will help. Remember that the shell is just the primary quantum number number. It is an energy level, with a defined geometry, a region of space in which it is probable to find the electron with that quantum number.