I have a basic question about how water dissolves salt. In the Khan Academy explanation, it says that the H and Cl atoms attract each other while the O and Na atoms attract each other.

My question: Does this weaken the bond between Na and Cl within a single NaCl molecule? Or does it weaken the bonds between Na of one molecule and Cl of another salt molecule? Or does dissolution weaken both?

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    $\begingroup$ NaCl doesn't exist as molecules; it's an ionic solid. $\endgroup$ – orthocresol Apr 5 at 4:54
  • $\begingroup$ What is the difference? Also, how important is that distinction at the beginner level of chemistry I'm at? $\endgroup$ – WeCanLearnAnything Apr 5 at 5:13
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    $\begingroup$ See: chemguide.co.uk/atoms/structures/ionicstruct.html and it's really quite important. If you haven't learnt that yet, you will very soon. $\endgroup$ – orthocresol Apr 5 at 5:23

There are no $\ce{NaCl}$ molecules in the solid salt nor in solution.

In solid salt, there are $\ce{Na+}$ ions, surrounded by 6 $\ce{Cl-}$ ions, while each $\ce{Cl-}$ is similarly surrounded by 6 $\ce{Na+}$ ions. Here is the Wikipedia picture of the structure.

During the dissolution, water molecules reach for a particular ion, oriented toward it by the opposite partial charge of their electric dipole.

$\ce{Na+}$ ions are torn away and wrapped by $\ce{O}$ side of $\ce{H2O}$ molecules, which have a partial negative charge.

$\ce{Cl-}$ ions are torn away and wrapped by $\ce{2H}$ side of $\ce{H2O}$ molecules, which have a partial positive charge.

Ions end hydrated in solution like $[\ce{Na(OH2)}_n]^+$ and $[\ce{Cl(H2O)}_m]^-$

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  • $\begingroup$ Got it. Thank you! Not sure if this question belongs in the same thread or not, but how can we still call it "salt" if the Na and Cl are separated? If the ionic bonds are broken, how does it retain its salty taste? Hasn't it undergone a chemical reaction? $\endgroup$ – WeCanLearnAnything Apr 5 at 7:34
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    $\begingroup$ Taste of the solid salt does not exist. Tongues do not know the taste of salt otherwise but as the taste of dissolved and separated ions. BTW the equimolar mixed solution of NaCl and KNO3 has the same taste as the similar solution of KCl and NaNO3, as there is no difference in the solution. $\endgroup$ – Poutnik Apr 5 at 8:19
  • $\begingroup$ Interesting. How far separated can those ions be and still have the taste of salt? Also, why are they still called ions if they're separated? How is the Na still giving the Cl an electron? $\endgroup$ – WeCanLearnAnything Apr 5 at 19:12
  • $\begingroup$ It is limited by concentration threshold of salt taste detection. When they are separated, and even when in solid salt, no Na+ ion belongs to a particular Cl- ion and vice versa. In solution, they diffuse independently. Why not to call them ions when they have a charge ? Why giving? Na gave it before the crystal of salt was created. $\endgroup$ – Poutnik Apr 5 at 19:25

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