* Electronegativity: This measures an atom's tendency to attract electrons in a bond.

* Ionic Bonding: Forms when one atom (the more electronegative one) gains electrons and becomes an anion (negative ion), while the other atom loses electrons and becomes a cation (positive ion). The strong electrostatic attraction between these oppositely charged ions creates the ionic bond.

Typical examples:

* Metals and Nonmetals: These usually have the most significant electronegativity differences. For example, sodium (Na) is a metal with low electronegativity, and chlorine (Cl) is a nonmetal with high electronegativity. They react to form sodium chloride (NaCl) or table salt.

* Some Nonmetals: Even some nonmetals can form ionic compounds with each other if their electronegativity difference is large enough. A good example is the reaction between oxygen (O) and fluorine (F) to form oxygen difluoride (OF2).

Key Takeaway:

The formation of an ionic salt requires one element to be a strong electron donor (metal or a less electronegative nonmetal) and the other to be a strong electron acceptor (nonmetal or a more electronegative nonmetal).