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Electron Sharing and Bonding

11/23/2015 8:12 AM

Hello everyone, I am a bit confused.

They say unlike charges attract one another, like charges repel, then why does in covalent and ionic bonding, electrons connect and share one another? Are not the two repel each other? I am confused so much.

Thank you.

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#1

Re: Electron Sharing and bonding

11/23/2015 8:30 AM

You're thinking the electrons bond to each other. They don't. Bonding has to do with electron shells around the atom.

The first shell can contain 2 electrons. The second can contain 8 electrons, and so on. An atom is "happiest" with a full electron shell. In physics terms, "happiest" means at the lowest energy.

So with covalent bonds (example: water), the bonded electrons spend time in shells of both atoms. The single electron in each hydrogen atom helps complete the outer shell of the oxygen atom, which has 6 electrons and needs two more to complete its outer shell.

In ionic bonds (example: salt NaCl) the cation (Na) gives away its only electron in the outer shell to the anion (Cl) which needs just one more to complete its outer shell. In this case neither sodium nor chlorine atoms have a partially filled shell, a win-win for both.

You might be confused with the term paired electrons. Two electrons with opposite spins (a pair) can share the same energy level. Thus there is one energy level in the first shell (2 electrons), four in the second shell (8 electrons) and so on.

https://en.wikipedia.org/wiki/Pauli_exclusion_principle

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#2
In reply to #1

Re: Electron Sharing and bonding

11/23/2015 12:27 PM

Good answer.

I'd add that even though the electrons have a negative (-) charge and want to repel, they are fairly close to the strong positive (+) charge of the protons in the atom's nucleus. That strong positive charge helps neutralize the effects of the (-) to (-) repulsion*. The net charge is zero since the sum of all the negative charges equals the sum of all the positive charges.

* Think of having 2 bar magnets placed side-by-side with like poles facing the same direction. They will repel. But if you stick the 'north' faces of the bar magnets onto a piece of steel you can slide them pretty close to each other. The effect of the repulsion is reduced by the ferromagnetic effect of the iron.

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#5
In reply to #2

Re: Electron Sharing and bonding

11/23/2015 11:46 PM

This magnet-stick analogy is a really good one. I think this guy should play with some neo magnets and a ball bearing and see how many he can stick all north to the ball. I've done this, and it is revealing to the the understanding of like and unlike charges. The actual forces at work in the magnet-stick are similar enough to get a feel for the differences between attraction and repulsion in the same fields.

When I stick a bunch of charges, (in this case small cylindrical neo magnets all in the same repulsive orientation) to a steel ball that all of the charges are attracted to, I find that I can stick only so many to the ball before the last magnet refuses to stick and flips over. This shows the measure of the saturation of the steel with magnetic field. There is a similar thing happening in the bonding of atoms, only in the case of atoms, the saturation point is a multiple of single value charges, electrons, so the system is physically uniform all over the universe, and not dependant upon the availability of a certain neo magnet and a certain steel ball. Still, playing with this and trying to press the greatest number of magnets onto a steel ball will make the charge limits very clear!

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#3

Re: Electron Sharing and bonding

11/23/2015 12:42 PM
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#4

Re: Electron Sharing and Bonding

11/23/2015 3:03 PM

Its all about minimum energy,

In certain situations two or more atoms "sharing" an electron is the energy minimum.

http://www.800mainstreet.com/5/0005-001_cov-bonds.html

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