What was the action between the 2 atoms in an ionically bonded compound that caused that ionic bond to form in the first place? mutual electrons interlocked attraction between electron cloud of one atom and nucleus of the other opposite ions attracted each other sharing of outer shell electrons

            Opposite ions attraction between the 2 atoms in an ionically bonded compound causes the ionic bond to form in the first place.

Explanation:
                   Ionic bond is the electrostatic forces of attraction between positively charged cations and negatively charged Anions. These forces are very stronger resulting in increasing several physical properties of Ionic compounds like melting point and boiling point e.t.c.

Example:

Sodium Chloride:
                           NaCl is formed by Na⁺ cation and Cl⁻ anion as follow,

Oxidation of Na;

                                      2 Na  →  2 Na⁺  +  2 e⁻

Reduction of Cl₂;

                                    Cl₂  +  2 e⁻  →  2 Cl⁻

Crystal Lattice formation is as follow,

                                  Na⁺  +  Cl⁻   →  NaCl