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Chemistry Forums for Students => Undergraduate General Chemistry Forum => Topic started by: leni29 on November 17, 2020, 02:45:50 AM

Title: How to determine what an atom is depicted from image of its orbitals
Post by: leni29 on November 17, 2020, 02:45:50 AM
Hello everyone!
So I will duplicate the question from the subject How to determine what an atom is depicted from image of its orbitals

(https://i.ibb.co/BC5dhKP/orbitals.png) (https://ibb.co/BC5dhKP)

So the possible answers are given as

It could be C I guess from sp3 state but in it requires H atoms to form the tetrahedron shape.
Could you explain why it is then B (my gut feelings tell so but I dk why)
Title: Re: How to determine what an atom is depicted from image of its orbitals
Post by: Corribus on November 17, 2020, 10:03:14 AM
Is this a translation? The question makes no sense to me. All isolated atoms have the same atomic orbitals. There are differences of course in the way they are filled and their relative energies, but I see no way to determine this by inspection. If they mean for you to make inferences about molecular bonding due to hybridization or whatever, then that's not indicated in the way the question is worded.
Title: Re: How to determine what an atom is depicted from image of its orbitals
Post by: NDW on November 17, 2020, 11:16:36 PM
The circle in the center is an S orbital. I also see Px and Py orbitals. B and C are the only two elements on the list that have P orbitals, so it has to be one of those. Given there are two P orbitals I think it's C.
Title: Re: How to determine what an atom is depicted from image of its orbitals
Post by: AWK on November 18, 2020, 12:55:21 AM
Orbitals are mathematical functions. Atoms have electrons in their orbitals. You give no information about the number of electrons in the orbitals.
So it's just a drawing with no description.
Title: Re: How to determine what an atom is depicted from image of its orbitals
Post by: Borek on November 18, 2020, 03:16:56 AM
The circle in the center is an S orbital. I also see Px and Py orbitals. B and C are the only two elements on the list that have P orbitals, so it has to be one of those. Given there are two P orbitals I think it's C.

This is sad. You can be right in terms of "answer the teacher was looking for" but it is wrong on many levels, suggesting whoever asked the question is ignorant.
Title: Re: How to determine what an atom is depicted from image of its orbitals
Post by: Corribus on November 18, 2020, 10:28:25 AM
The circle in the center is an S orbital. I also see Px and Py orbitals. B and C are the only two elements on the list that have P orbitals, so it has to be one of those. Given there are two P orbitals I think it's C.
As borek said, it may be the answer the writer of the question was looking for, but for posterity this is wrong for two reasons:

(1) There are no spatial axis designations, so we can't say what orientation the p-orbitals have.

(2) Every element has, or can have, p-orbitals. There's a bit of a philosophical question of whether an orbital exists if there are no electrons in it. Even allowing for the assumption that the answer is no, atoms can still exist in excited states, in which these orbitals may become filled anyway. Even hydrogen has a filled p-orbitals (and d-orbitals, etc.) under certain conditions. Then there's the fact that the question makes no mention of whether these are neutral or charged atoms, or whether the orbitals shown are atomic or molecular orbitals.

It's just a really bad question.

Title: Re: How to determine what an atom is depicted from image of its orbitals
Post by: NDW on November 18, 2020, 08:54:27 PM
I am simply providing the answer the instructor is looking for. Given the question, the OP is clearly not at the stage to get into any details or technical correctness.
Title: Re: How to determine what an atom is depicted from image of its orbitals
Post by: NDW on November 18, 2020, 09:08:19 PM
I will also add that you will have great struggles if you try to be 100% literal, rigorous, and technically correct when answering a prof's questions. The reason is that profs rarely write rigorous questions; there are usually holes that can be poked in them. A lot of times you just have to guess at what they are asking. It really is an art.
Title: Re: How to determine what an atom is depicted from image of its orbitals
Post by: Corribus on November 18, 2020, 09:31:35 PM
I will also add that you will have great struggles if you try to be 100% literal, rigorous, and technically correct when answering a prof's questions. The reason is that profs rarely write rigorous questions; there are usually holes that can be poked in them. A lot of times you just have to guess at what they are asking. It really is an art.
What we should strive for is technical correctness and complete understanding of key concepts, not getting questions correct merely for the sake of getting them correct. There is no harm in pointing out to students when they have been given bad questions to answer. In fact, there is harm in not pointing these out, and on this forum I will do so without hesitation. Getting an A on a test today means nothing if you don't understand concepts tomorrow. This will make it that much harder to correctly answer good quality questions later on, either in more advanced classes or in life.

I also need not point out that a professor who writes a question like this (or reproduces it from a text) is either lazy, incompetent, or doesn't know the material he/she is trying to teach. In either case, do you really want to learn from such a person? Can you learn from such a person? /rhetorical question.
Title: Re: How to determine what an atom is depicted from image of its orbitals
Post by: leni29 on November 24, 2020, 10:27:56 AM
I will also add that you will have great struggles if you try to be 100% literal, rigorous, and technically correct when answering a prof's questions. The reason is that profs rarely write rigorous questions; there are usually holes that can be poked in them. A lot of times you just have to guess at what they are asking. It really is an art.

I totally understand the absurdity in this question. There is no direct link between the atomic orbitals shapes and atoms they represent. At least it is difficult to visualize orbitals without some special software like Gaussian or solving the wave function equation. But this... the question is taken from a Russian examination Chemistry class and I could not understand is there any valid approach.  I don't think that it is even taught how to solve questions like these well because those questions are bad and nobody teaches that.
Thank you everyone who contributed to solving this question and pointing why the question is bad. I appreciate your help very much!
Title: Re: How to determine what an atom is depicted from image of its orbitals
Post by: penta-d on November 24, 2020, 01:15:20 PM
... the question is taken from a Russian examination Chemistry class and I could not understand is there any valid approach. 

Perhaps the question was mistranslated from Russian? Otherwise, I can't think of a valid approach to the problem.
Title: Re: How to determine what an atom is depicted from image of its orbitals
Post by: leni29 on November 26, 2020, 11:46:51 AM
Ugh, it is awkward but I mistranslated it a little bit. So the correct version of the question would to which atom corresponds to the drawn orbital shape in its excited form.

The image shows as many correctly pointed a s-orbital sphere in the center and 2 p-orbitals (one along x, other along y). Those 2 orbitals are px and py.

So the electronic configuration should be 2s22px2py.

From given options carbon is the most that fits the description if we imagine its one electron from 2px is promoted to 2py

I am not sure how it is technically would be correct but it seems to be only reasonable explanation of the shapes
Title: Re: How to determine what an atom is depicted from image of its orbitals
Post by: Corribus on November 27, 2020, 12:29:24 PM
Not to offend, but this makes even less sense, because atoms have, literally, an infinite number of excited states. Who is also to say those are n = 2 p orbitals? I think we just need to accept that the diagram does not provide enough information for any kind of reliable interpretation.

Also 2s2 2px(1) 2py(1) is only an excited state of a carbon atom in certain spin state configurations, and there's no way to infer spin states from the diagram.