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Old December 19th, 2011, 05:40 AM   #1
tara
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Question Na or Na+ (stability) help!

Na is more stable or Na+?
I think there is a paradox here ... please don't say that Na+ is more stable because it reaches the octet (Ne)...I know these I just need you to explain why my explanation below is not correct and disprove it:

Na is more stable than Na+ because we should give it the energy to remove e and make Na+:
"Ionization energy is defined as the energy needed to remove an electron from a gaseous atom."
so the equation Na + q ----> Na+ + e , is endothermic (Na+ has a higher energy) and if we draw the curve , it goes up ,so the stability of Na+ is less than Na.

thank you!
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Old December 20th, 2011, 02:24 AM   #2
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You can say it like that, the only thing which really makes Na+ more stable is when it actually reacts.

Indeed, when it does, it will combine with another ion which then releases much more energy than the energy you used to form the Na^+ ion.

Simple example is reacting Na with water. Why is the reaction so exothermic? The great deal of energy released from the reaction compensates the energy required to ionise Na.

I hope that makes sense and your thoughts are correct.

Like for example, if you had Na ions in a vacuum, they won't change to Na^+ to be come more stable In another way, they would be becoming electronically less stable.
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Old December 20th, 2011, 06:03 AM   #3
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Thanks! Na ions should just be in vacuum for not reacting with other atoms?
Then why Na can be stored in mineral oil and it doesn't react with it?
when Na turns to Na+ and electron , the electron has the energy that is released when Na reacts with for example Cl?

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Old December 20th, 2011, 07:34 AM   #4
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Quote:
Originally Posted by tara View Post
Thanks! Na ions should just be in vacuum for not reacting with other atoms?
Well, now you should really precise what sort of sodium ions we're speaking about. If it's in water, then you have water molecules around it which makes is so you have 'free' Na ions.

Otherwise, even in a vacuum, it would have to be kept with an electric field. As the ions are charged, they will tend to snatch electrons from the walls of whatever container they are in to attain electronic stability. But assuming it's inert, then yes.

Quote:
Then why Na can be stored in mineral oil and it doesn't react with it?
Remember that when there is a chemical reaction, the properties of an element might change. In this case, you're comparing a neutral atom with its ion!

Or if you want, the Na ions are in a sea of electrons, as sodium is a metal and the oil does not take the electron (or maybe it requires far too much energy to do so). Hence the Na ions remain with the electrons and no reaction occurs.

Quote:
when Na turns to Na+ and electron , the electron has the energy that is released when Na reacts with for example Cl?

The electron does not have the energy strictly speaking. It is the reaction of the electron plus a chlorine atom which releases part of the energy. Chlorine is much more stable with a complete octet.

And then, additional energy is released when the positive Na ion and the negative Cl ion bind together.

Together, they are larger than the energy required initially for ionisation. Now imagine you do such a reaction. Only a little energy is needed to start that reaction and this can be obtained from the heat from the environment itself. Assuming that only one atom reacts, this will produce a lot of energy which will cause adjacent atoms to react.

And this goes on and on until everything reacted. Conclusion, only a small energy was required and in the end, a lot of energy was released, significantly much more.
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Old December 20th, 2011, 08:34 AM   #5
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Quote:
It is the reaction of the electron plus a chlorine atom which releases part of the energy. Chlorine is much more stable with a complete octet.
And then, additional energy is released when the positive Na ion and the negative Cl ion bind together.
Quote:
If it's in water, then you have water molecules around it which makes is so you have 'free' Na ions.
For example we have lab and we put a sodium bar in water and we make some sodium ions from the bar. Here the Na+ is free... so the energy that u talked about can't be released.(no reaction)
here the paradox returns!
Quote:
Conclusion, only a small energy was required and in the end, a lot of energy was released, significantly much more.
Can we use this energy and store it?!

P.S:I really can't stop myself asking questions when sb answers this much good !
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Old December 20th, 2011, 09:23 AM   #6
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Quote:
Originally Posted by tara View Post
For example we have lab and we put a sodium bar in water and we make some sodium ions from the bar. Here the Na+ is free... so the energy that u talked about can't be released.(no reaction)
here the paradox returns!
Nuh huh! You forget something! A reaction already occurred and that is the reaction of water with sodium!

2H2O + 2Na ---> 2NaOH + H2

The water heats up and the sodium even catches fire and melts. If that is not energy being released, I don't know what it is

The Na becomes ionised and when it becomes surrounded by water, small bonds between the sodium and the water molecules are formed. Just like the sodium ion becomes trapped in a bubble. The formation of those small bonds are what cause the energy released.

Quote:
Can we use this energy and store it?!

P.S:I really can't stop myself asking questions when sb answers this much good !
Well, I'm sure you could use the energy released when sodium reacts with water... but you have to understand that to obtain the metal sodium itself is not cheap, nor easy, nor requiring less energy than it produces.
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Old December 20th, 2011, 10:24 AM   #7
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Quote:
Nuh huh! You forget something! A reaction already occurred and that is the reaction of water with sodium!
Uh huh! yeah sorry! It seems I can't find something to continue the paradox! So sodium can't become Na ion without a reaction between it's released electron and an electronegative atom...

Thanks really
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Old December 20th, 2011, 10:26 AM   #8
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Indeed and you're welcome
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