Final answer:
Electronegativity is a measure of an atom's ability to attract electrons when it is part of a compound. It is a relative quantity that increases from left to right across the periodic table. The most electronegative element is fluorine.
Step-by-step explanation:
Electronegativity is a measure of the ability of an atom to attract the electrons when the atom is part of a compound. It is a relative quantity that is calculated, not measured. Electronegativity values generally increase from left to right across the periodic table. The most electronegative element is fluorine, with an electronegativity value of 3.98. Electronegativity measures the ability of an atom in a covalent bond to attract the shared electron pair(s).