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Electronegativity is a measure of the attraction an atom has for electrons when it is involved in a chemical bond. First, look at your table of Electronegativities. Noble gases have no electronegativity because they generally do not bond. Fluorine- 4.0 the highest Fr and Cs 0.7 the lowest
Why? Elements that have high electronegativity are small atoms with their outmost electrons close to the nucleus. This increases the effective nuclear charge of the atom. In other words, the nucleus can readily attract electrons to the closer unfilled principle energy level versus larger atoms where the outmost occupied principle energy level is further from the nucleus. Right now, focus on
Using Electronegativity Values The electronegativity differences between atoms can be used to determine the type of bonding that occurs. However, this method is limited is flawed. It can be used to determine which bond has more ionic or covalent "character". If the difference between 2 atoms is small (less than 1.7) the bond is "mostly" covalent. If the difference is large (greater than 1.7) the bond is considered "mostly" ionic. Some Flaws- HF is covalent not ionic (difference of 1.9) BF3 is covalent (difference of 2.0) BeF2 is covalent (difference of 2.5)
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