•  Elements with the highest ionization energies are those with the most negative electron affinities, which are located in the upper-right corner of the periodic table.
	•  Elements with the lowest ionization energies are those with the least negative electron affinities and are located in the lower-left corner of the periodic table.
	•  The tendency of an element to gain or lose electrons is important in determining its chemistry.
	•   Various methods have been developed to describe this tendency quantitatively.
	•   The most important method is called electronegativity (), defined as the relative ability of an atom to attract electrons to itself in a chemical compound.