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Author Topic: Sodium want to lose or gain an electron?  (Read 7137 times)

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crazysexycool

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Sodium want to lose or gain an electron?
« on: November 14, 2005, 03:09:44 PM »

Hi the question is:

Does the sodium atom want to lose or gain an electron? Explain your answer (IE of Na is positive and the electron affinity is negative)

I think that...the position on the table suggeset that sodium wants to loose an electron, but it actually wants to gain an electron.
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constant thinker

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Re:Sodium want to lose or gain an electron?
« Reply #1 on: November 14, 2005, 03:21:04 PM »

I think that...the position on the table suggeset that sodium wants to loose an electron, but it actually wants to gain an electron.

Where in the world have you read that in wants to gain an electron? It would need to gain 7 electrons to form an octet. Hydrogen and helium are the only 2 atoms that need 2 electrons in their outer shell to make it full.

It would be much easier for the Na to lose an electron. It's oxidation number is +1.


P.S. (to Mitch and company) I tried to refrain from saying anything but I did anyways.
« Last Edit: November 14, 2005, 03:23:07 PM by constant thinker »
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crazysexycool

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Re:Sodium want to lose or gain an electron?
« Reply #2 on: November 14, 2005, 03:25:48 PM »

Hi,
yes this is what i thought, but according to my professor, sodium does not want to loose an electron, but gain an electron!

I would ask my prof, but he has 300 students from the same class and it is just impossible to get a hold of him!
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mike

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Re:Sodium want to lose or gain an electron?
« Reply #3 on: November 14, 2005, 03:35:20 PM »

Sodium would prefer to lose one electron to form stable octet.

In its atomic state sodium has one valence electron, maybe this is what the prof meant, I am not sure. The sodium will then try and donate that electron to something.
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Re:Sodium want to lose or gain an electron?
« Reply #4 on: November 14, 2005, 11:40:18 PM »

Yes, sodium can also gain 1 electron. There is known a complex of NaH with crown ether, where  H+ exists with no doubt.
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mike

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Re:Sodium want to lose or gain an electron?
« Reply #5 on: November 15, 2005, 04:02:14 PM »

Yes good point NaH is sodium which has gained an electron, -1 oxidation state, 1s2.

So what is the right answer to the original question? I would say that sodium tends to lose an electron, what do others think? Should the answer be both lose and gain an electron? (maybe depends on the level of the student?)
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Re:Sodium want to lose or gain an electron?
« Reply #6 on: November 15, 2005, 08:32:53 PM »

Loosing electrons is prefered, gaining is an exception ( so far an only one).
Exceptions proves the rules!
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SLOdown

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Re:Sodium want to lose or gain an electron?
« Reply #7 on: November 17, 2005, 12:35:26 PM »

HUH?

First of all, what is all this talk about sodium "wanting,"  or  "prefering"  to do anything?  Atoms don't have feelings.

As far as gaining or losing electrons, if a sodium atom loses an electron, and a chlorine molecule happens to pick up that electron, NaCl(s) can form.  This is way lower in potential energy than the reactants, so this reaction is spontaneous.  Find lattice energy in the index and look at the diagram for this in your text.  The student is correct in that E must be absorbed by Na to form Na+, and a little E is released in forming Cl-, but the majority of the E released is from the two ions coming together.

As far as IE goes, if you check your gen chem text, the ionization energy for every single element is +, meaning it requires E to separate atoms from electrons.  Does this mean that cations don't exist?  Of course not.

EA and IE are useful concepts/data to help explain what is going on in a chemical reaction, but these numbers are for gas phase reactions of atoms.  

About NaH:  there isn't much support for this compound to be labeled as Na- and H+.  This compound reacts with water (and other proton sources) to form H2 gas, leaving behind an anion (OH- if it's reacting with water).

There is the odd Na-  H+ compound, but someone worked really hard to make this:   http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=12022811&dopt=Abstract

So the original poster did a nice job questioning her prof, and trying to reason stuff out.  But please, no more atomic feelings!  Atoms gain or lose electrons to form compounds, but they don't do this unless enough energy is returned by new bonds forming.  Check out the difference in the IE's of Na and then of Na+ and you can see the difference.

cheers!


Yes good point NaH is sodium which has gained an electron, -1 oxidation state, 1s2.

So what is the right answer to the original question? I would say that sodium tends to lose an electron, what do others think? Should the answer be both lose and gain an electron? (maybe depends on the level of the student?)
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mike

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Re:Sodium want to lose or gain an electron?
« Reply #8 on: November 17, 2005, 01:23:37 PM »

Quote
First of all, what is all this talk about sodium "wanting,"  or  "prefering"  to do anything?  Atoms don't have feelings.

Yes very good, atoms don't have feelings (as far as you know ;)) but these are terms quite commonly used when talking abouth electrons. Similar to phrases like:

Quote
and a chlorine molecule happens to pick up that electron

molecules don't have arms last time I checked, how does it "pick up" this electron? :D

You do provide some nice answers though. Do you think that the student should also mention the position on the periodic table and mention octet rules etc??

Quote
About NaH:  there isn't much support for this compound to be labeled as Na- and H+.  This compound reacts with water (and other proton sources) to form H2 gas, leaving behind an anion (OH- if it's reacting with water).

There is the odd Na-  H+ compound, but someone worked really hard to make this:

good points :)
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