Electronegativity and Bond Type: Predicting Bond Type

• Published in: Journal of chemical education 2001-03, Vol.78 (3), p.387
• Main Author: Sproul, Gordon
• Format: Article
• Language: English
• Subjects: Acidity; Chemical bonds; Chemical reactions; Chemistry; Electromagnetism; Electronegativity; Organic chemistry; Polarity
• ISSN: 0021-9584; 1938-1328
• DOI: 10.1021/ed078p387

While most general chemistry textbooks recognize that differences in electronegativity between bonded atoms provide only an indication of bond type, the difference function of electronegativity itself is both inadequate and improper for determining bond type. An alternative algorithm based on the unfunctionalized values of electronegativity for the two bonded atoms in binary compounds of representative elements provides much better discrimination between ionic and covalent bonding. This algorithm not only removes the ambiguity introduced by the difference function, but at the same time provides for the natural inclusion of the third type of interatomic bond--metal-metal bonding. Textbook authors should indicate that the absolute values of electronegativity, not their differences, are most useful for predicting bond type. Also, the value of electronegativity of the element of higher electronegativity in binary compounds determines whether the compound will be metallic. If a compound is not metallic, the electronegativity of the element of lower electronegativity determines whether the compound will exhibit primarily ionic or covalent character if that element is representative. If the element of lower electronegativity is a transition metal, the bond character is not predictable using electronegativities alone.