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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?

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

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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.

John T
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3 Answers3

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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?

Tony Stark
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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.

Vaibhav Pankhala
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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!

Gert
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