We know that if Cl and Na get too close, they produce ionic bonding.
Cl has 17 proton and 17 electrons and is considered stable.
Na has 11 protons and 11 electrons and is considered stable.
I understand that in Na, we have 1 valence electron and in Cl, we have 7 valence electrons. Now, if they get too close, 1 valence electron is transferred from Na to Cl. I don't understand why. Na was already stable. I get that part that Cl, since it has more protons, it would attract the electron from Na more than Na would do for itself due to less protons(11), but when ionic bond happens, Cl would end up having 17 proton and 18 electrons. Wouldn't Cl itself become unstable as there're more electrons than protons ? It seems like that before bonding, they both were stable, but after bonding, Cl ended up not stable.
I'm trying to understand it, but I get a point that explanation with quantum would be a waste of time as I have no knowledge in quantums. So would appreciate the explanation in terms of attraction forces and why after bonding, Cl doesn't become unstable. Note that octet rule and staff like this is something I don't really need to know as they're rules and not explanation in terms of attractions. I checked this why do atoms want to have a full outer shell but doesn't help.