Final answer:
Electronegativity measures the ability of an atom to attract electrons in a chemical bond, with fluorine being the most electronegative element. It is different from electron affinity or ionization energy and is not directly measurable but derived from comparative data.
Step-by-step explanation:
Electronegativity is a measure of the attraction by an atom for electrons in a chemical bond. It is a relative scale that gauges how strongly an atom in a molecule attracts bonding electrons to itself. The value of electronegativity increases across the periodic table from left to right, and the element fluorine has the highest electronegativity value.
It's important to distinguish electronegativity from electron affinity and ionization energy. While electron affinity refers to the energy change when an electron is added to an isolated atom, and ionization energy is the energy required to remove an electron from an isolated atom, electronegativity considers how tightly an atom attracts electrons when it is part of a compound.
Electronegativity values are not fixed properties and cannot be directly measured in a single experiment, they are instead deduced from comparing other properties, such as ionization energy and electron affinity. All methods for determining electronegativity tend to agree on the relative values for elements, confirming that they measure a consistent property related to an atom's ability to attract bonding electrons in a compound.