But because of the size of the potassium, because of it being just the perfect radius, just the perfect size, it can form these intermolecular interactions, which are overall more stable than these intermolecular interactions. And so the sum of those two values produces a negative free energy, and this reaction takes place spontaneously. Now, in the case of the sodium ions, this is what we basically see. The sodium ions form these stabilized interactions with the water molecules. And so this is our sodium atom. These are the interactions.