Answer: An atom's ability to attract other electrons and form a chemical bond
Step-by-step explanation:
The electronegativity of an atom tells of its power to attract electrons. Electronegativity values of elements ranges from 0 to 4.0, a high value means higher ability to attract electrons while a lower value means lower ability to attract electrons. Also, a wider difference in electronegativity between two atoms gives an ionic bond unlike a covalent bond with narrow difference.
Thus, nonmetals like chlorine higher electronegativities than metals like potassium.