Atom charge forces and ionic bounding

Question

Why do electrons form shells/clouds around nucleus? If electron is negative charge and protons in nucleus are positive they should attract each other and as a end result stick in one place?

Second question (an I think it's related) is about ionic bonding. I think this is most popular example:

But why does the electron jump from Na to CL? The octet rule makes very less sense for me, as it says "Atoms try to get 8 electron in outer shell", and it's rather incomplete and abstract explanation.

And more over, why is is sometimes Ionic Bonding and sometimes Covalent Bonding?

Edit:

Dear members stop voting for duplicate and read the whole thing. This topic answers multiple linked questions, not just one (1st that is similar) and I picked already a solution.

Are you sure this question does not belong to Chemistry , especially the second part? — Tony Stark, Aug 18 '20 at 09:43
I think I want to answer the question from perspective to atom physics. Chemistry will just say "well metals like to give away electron to non-metals" — John T, Aug 18 '20 at 09:49
For the first part, why doesn't circular motion in Bohr model sounds good enough to you? — Tony Stark, Aug 18 '20 at 10:03
@TonyStark that won't enough because his model answers they orbit in certain paths but doesn't answer why it happens so that's why quantum mechanics came into play. — Vaibhav Pankhala, Aug 18 '20 at 10:08
@VaibhavPankhala I don't see how Heisenberg principle answers my question. If you could explain it in a answer? — John T, Aug 18 '20 at 10:15
I never knew this feature my ans is trivialhow does the system identify trivial answers? — Protein, Aug 18 '20 at 11:44
Does this answer your question? Why don't electrons crash into the nuclei they "orbit"? — Protein, Aug 18 '20 at 11:45
Please stop trolling with your "this is already answered" thing. You should notice this question has multiple topics and I already picked a Solution. So just relax and back of. — John T, Aug 18 '20 at 13:55
https://www.youtube.com/watch?v=f8FAJXPBdOg watch this famous science song in which he also said answer of your question is uncertainty principle.watch at 0:35 — Vaibhav Pankhala, Aug 19 '20 at 03:07
I specially added a comment: "Dear members stop voting for duplicate and read the whole thing. This topic answers multiple linked questions, not just one (1st that is similar) and I picked already a solution" and people still vote for closing because dupe. What the hell is this? Eye or intellect problems? Read first line an ignore rest? Fanatic urge to close something (are there some bonuses for that?)? Now a valuable topic with valuable answers is closed for no good reason. I don't understand. — John T, Aug 20 '20 at 17:20

score 1 · Answer 1 · answered Aug 18 '20 at 09:58

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I am answering second part

But why does the electron jump from Na to CL? The octet rule makes very less sense for me, as it says "Atoms try to get 8 electron in outer shell", and it's rather incomplete and abstract explanation

Well when electron is removed from Sodium,we have to provide energy to it -- Ionization energy . This is because work needs to be done to remove it against net nucleus force as a whole. If you have ever wondered about screening effect in Chemistry, it happens because there is electronic repulsion present (smaller compared to Nuclear attraction) and hence net force decreases.(notice I have highlighted net.)

When an electron is given to Chlorine it releases energy -- Electron Gain Enthalpy.This follows same argument. Nucleus does work when electron comes near it. Its potential energy decreases and hence energy released.

When the two ions are brought close it releases energy -- Lattice energy. This is because of strong electrostatic force of attraction between positive and negative ions. Hence Potential energy decreases again and energy is released.

Net result is Potential Energy being released and the system being in stable equilibrium.

Sounds Physics enough?

answered Aug 18 '20 at 09:58

Tony Stark

1,538

It still doesn't answer my question. You started your answer with "Well when electron is removed from Sodium", but that exactly my question. Why it is removed in first place? What forces make it go from here to there? – John T Aug 18 '20 at 10:07
Heat - for most cases. When you place the reactants in a jar , many a times they take up energy from surroundings - say wall and the reaction starts.This reaction proceeds and heat is transferred from walls towards middle. In some cases ,external heating may be required.Then comes molecular collisions .When the electrons are excited from heat and their atoms collide they may be ejected from their positions for a short time and in this short time the reaction happens.Plus we have to take into account molecular orientation. – Tony Stark Aug 18 '20 at 10:11
Can I satisfy your doubt? – Tony Stark Aug 18 '20 at 10:16
But the experiments talk about that bringing NA close enough to CL and the electron shift happens. And I want to know why. What are the forces behind it. – John T Aug 18 '20 at 10:18
It still doesn't answer my question Please bear in mind you're asking several, quite complicated questions that don't have a simple 'one A4 page answer'. Have some pity on the poor devil who tries to answer here. But Tony Stark's answer is far from perfect. – Gert Aug 18 '20 at 10:21
@Gert critics taken.... – John T Aug 18 '20 at 10:23
@Gert Sir I agree much better answers can be made but my answer is mainly targeted to people who are new to Physics and do not understand QM. – Tony Stark Aug 18 '20 at 11:09

score 1 · Answer 2 · answered Aug 18 '20 at 10:31

The Heisenberg Uncertainty Principle explains why electrons do not fall into the nucleus of an atom.The principle specially states that the product of the uncertainty of position and the uncertainty of momentum is greater than or equal to Planck’s reduced constant divided by two.

Anyway, let’s say that the electron has collapsed into the nucleus.

(This was predicted by classical mechanics. Harmonic oscillators- in this case, the orbiting electron- continuously emit energy.Therefore, an orbiting electron should emit energy, go lower in its orbit of the nucleus where it will orbit around the nucleus faster and emit more energy. Eventually the electron will collapse into the nucleus.)

This means that we know what the position of electron is with very little uncertainty.

Therefore, there is a lot of uncertainty about the value of the momentum of the electron. (This comes from rearranging the inequality I described above.)

If there’s a lot of uncertainty, the momentum is either very, very large in one direction, or very, very large in the other direction.

A large momentum means a large velocity, and therefore, a lot of kinetic energy.

The electron now has enough kinetic energy for it to be launched out of the nucleus and into an orbit of it due to the electromagnetic interactions between them.

Therefore, the electron won't collapse.this was answer of your first question according to me.

It's not a bad answer at all but really you don't need the UP to explain why electrons don't fall into the nucleus. Orbitals (the SE) predict very low probability for finding the electron in the nuclear range. — Gert, Aug 18 '20 at 10:59
i think both ways are correct. UP came one year after SE and it became an integral part of later QE formulations like Dirac's equation it was consistent with SE. — Vaibhav Pankhala, Aug 18 '20 at 11:22

score 1 · Accepted Answer · answered Aug 18 '20 at 10:36

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Why do electrons form shells/clouds around nucleus? If electron is negative charge and protons in nucleus are positive they should attract each other and as a end result stick in one place?

In a nutshell? The math from the Schrödinger equation describes where electrons 'reside' inside an atom and how they 'move'. I use quote marks here because quantum physics (the Schrödinger equation - SE) is profoundly counter-intuitive and terms like 'reside' and 'move' for electrons in atoms are quite problematic already.

One of the things the SE tells us is that electrons can basically not 'fall' into the nucleus, so the electrons never merge with the nucleus.

The octet rule makes very less sense for me, as it says "Atoms try to get 8 electron in outer shell", and it's rather incomplete and abstract explanation.

Again, what the SE predicts very convincingly is that octet electron configurations have very low energy (are very stable) and thus it's a state that atoms 'strive' to achieve.

This can be achieved by the formation of ion pairs (e.g. $Na^+/Cl^-$) or by covalent bonds where atoms share electrons (e.g. $CH_4$ - methane).

Abstract explanations are good by the way: it's what mathematical descriptions give us!

answered Aug 18 '20 at 10:36

Gert

35,289

So what you want to say is, that the electrons for some reason do not Obey the classical rules that negative (electrons) attracts positive (protons) and stick together? Due some quantum voodoo? :) – John T Aug 18 '20 at 10:42
Quantum voodoo is not a bad term. But here's it's called math! ;-) At some point you'll study the simplest quantum system of all: a particle in a $1D$ box: it'll give you a taste for QM's math induced weirdness. Voodoo if you prefer... – Gert Aug 18 '20 at 10:45
https://quantummechanics.ucsd.edu/ph130a/130_notes/node136.html – Gert Aug 18 '20 at 10:46
as much as I know lots for quantum weirdness is not yet explained with math and any kind of logic. Like how for example a electron of H "makes its way" to different orbitals and why :) – John T Aug 18 '20 at 11:03
Hmmm... there's VERY LITTLE quantum weirdness that hasn't been explained by math and logic, actually. QM is by far our most successful and most predictive theory. The formation of orbitals and the transitioning of electrons from one orbital to another is perfectly explained. See spectroscopy. – Gert Aug 18 '20 at 11:07
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wow did not know that. Can you drop a link, where the transitions to orbitals is explained? – John T Aug 18 '20 at 11:09
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https://chem.libretexts.org/Bookshelves/Physical_and_Theoretical_Chemistry_Textbook_Maps/Supplemental_Modules_(Physical_and_Theoretical_Chemistry)/Spectroscopy/Electronic_Spectroscopy/Electronic_Spectroscopy%3A_Interpretation It's difficult to point to one single page, as that field is vast and crowded, so I'm loathe to choose one. 'Orbital transitions' is itself multi-faceted. – Gert Aug 18 '20 at 11:15

Atom charge forces and ionic bounding

3 Answers3