Question

why does sodium chloride does not exist as a molecule but aggregates of oppositely charged ions? ​

Answer 1

Answer:

Explanation:

Salts are formed by oppositely charged ions coming together; ex.. Sodium cation (Na+) and chloride anion (Cl-) exist together to form sodium chloride crystals in solid state. Positive charge on the positive sodium cation attracts negative chloride ions around it, and vice-versa. These ions jostle each other, adjust and arrange themselves around the counter-ion in a thermodynamically stable crystal structure, which is cubic close packing in NaCl crystal.

In order for Sodium Chloride to exist as a neutral molecule, the 3s1 electron in the sodium atom must have to reside on the sodium atom, and the Chloride atom must remain deficient in one electron in its 3p5 state. As soon as the two atoms try to “share” the electron between the two atoms i the form of a “covalent bond”, the “sharing” becomes completely unequal, and the chloride atom snatches away the electron from sodium atom in its drive to complete the octe, thereby forming an “ionic bond”. So, even if you hypothetically created a solid structure for NaCl comprising of sodium atoms and chloride atoms, they would instantly rearrange to Na+ and Cl- ions because that forms the most energetically stable structure.

This is why NaCl does not exist as neutral molecules in solid or liquid state. Under high vacuum, it is possible to think of NaCl existing as a molecule in gaseous state, if only because it is isolated from the interaction with other Na+ or Cl- species. But even in this gaseous case, it is believed that it exists as Na+ and Cl- ions, held together by electrostatic forces of an “ionic bond”