eli5: Why does NaCl not blow up in water like Na? Doesn’t the molecule breaks into Na+ / Cl- in water?
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NaCl already is Na+ and Cl-. In solid form, those ions are neatly stacked in a lattice. When water is added, those ions just separate because water is polar and can act as a + on one side and a – on the other.
The violent chemical reactions are when a Neutral Na atom loses its ~~hydrogen~~ electron and when a neutral Cl atom gains its electron. Salt is ionic, the transfer has already taken place.
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Pure sodium is not electronically happy, and can’t even be stored in air without slowly reacting.
NaCl on the other hand… each of the Na+ and Cl- atoms are electronically happy. They have swapped an electron away from sodium and to chlorine.
An exothermic reaction would happen with elemental sodium and chlorine, similar sodium and water.
When the molecule of NaCl dissociates in water, as you mentioned, it’s just happy, charged, low energy atoms bumbling around and interacting with polar water molecules. No reaction takes place because they’ve already swapped that electron. Another swap with a water molecule to make a reaction between salt and water would require an incredibly high energy investment
Na has an extra electron that Na+ doesn’t. It’s that extra electron that makes Na react with many things, and lacking it, it’s perfectly happy to just hang around. The same goes for Cl vs Cl-, Cl lacks an electron and will go out of its way to react with things that have extra electrons. Cl- is happy.
NA+ isn’t as reactive as NA. Effectively the sodium has already reacted with the chlorine to form NA+ and Cl-. Splitting the salt apart doesn’t undo that reaction.
NA+ isn’t as reactive as NA. Effectively the sodium has already reacted with the chlorine to form NA+ and Cl-. Splitting the salt apart doesn’t undo that reaction.
Na is top and Cl is bottom and they are both nymphomaniacs. When Na is not positive it means it hasn’t quenched its thirst so it wants to give AGRESSIVELY, Cl is the same way but with receiving. When they get together, Cl gets and Na gives, so they are satisfied and are prone to dissociation in solution in more stable forms, that’ll be Na+ and Cl- (Na has given and Cl has received an electron).
When NaCl is added to water, the bonds between the Na and Cl do not break. So you just have NaCl molecules dissolved with H2O.
Na desperately wants to be Na+, that is what is causing the mayhem when Na meets anything that it can rob of some + (or rather: dump some – on).
Once it is Na+, as in NaCl (which is in reality more like Na+ Cl-) it is perfectly docile.
>Doesn’t the molecule breaks into Na+ / Cl- in water
Yes it does, but **Na+ is very different from Na, and Cl- is very different from Cl**. And the difference, having gained/lost 1 electron, is what makes those two elements so reactive in the first place!
**Sodium** – Na is highly reactive because its outer “shell” has one lone electron. It really “wants to” get rid of that straggler and just have the full, complete shell underneath that as its outer shell. When it does that, losing one electron, the Na becomes Na+ (electrons are negative so when you lose one you now have a +1 charge). So *the Na+ in NaCl is a Na that has already lost its reactive electron and is sitting stable and happy* with a full outer shell.
**Chlorine** – Cl is like the same thing in reverse. It’s reactive because its outer shell is only missing one electron. It really “wants to” gain one more electron, and will rip one off of nearly anything. When it does that, the Cl becomes Cl- (electrons are negative so when you gain one you now have a -1 charge). So *the Cl- is NaCl is a Cl that has already gained an electron and is sitting stable and happy* with a full outer shell.
Na+ and Cl- are like the “ash” of Na and Cl. It’s the already-reacted remnants of a formerly-reactive substance. [You can literally mix Na and Cl in a beaker and they violently burn and explode, leaving white powdery NaCl as the product at the bottom.](https://www.youtube.com/watch?v=ji_25I_q4LQ)
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