Electronegativity is a chemical trait indicating an atom’s ability to attract electrons. In other words, some elements attract electrons strongly. Also, there are elements that don’t crave electrons as much. And then there are elements that do not attract electrons at all. This keenness or tendency to engage electrons is electronegativity. The higher the electronegativity, the more affinity an atom has toward acquiring electrons. The opposite of electronegativity is electropositivity.
Electronegativity is not something that can be determined by a simple experiment. An element’s electronegativity is dependent on its chemical surrounding. Unfortunately, there is no straight method to measure electronegativity. In practice, an atom’s electronegativity is typically estimated and not calculated.
An atom’s electronegativity trait is determined by its nucleus’ ability to have a strong attractive pull on its electrons. The distant the electrons from the nucleus, the slightly difficult it becomes for the atom to hold on to its electrons. An atom usually has equal number of protons and electrons. Since a proton’s mass is several times more than the mass of an electron, protons are always the dominant force within an atom. This is why the more the number of protons, the higher the atom’s electronegativity.
Electronegativity Range and Periodic Table Positioning
The electronegativity range generally lies between numbers 4 and 0, with 4 representing extreme electronegativity and 0 indicative of the least electronegative atoms. On the periodic table, elements with increased electronegativity are located at the top right corner, and the ones with low electronegativity can be seen languishing at the bottom left of the table. Simply put, the periodic table’s overall electronegativity trend is diagonal, starting at the lower left and ending at the upper right.
Fluorine has the highest electronegativity at 4; it’s located in group 17 of the periodic table, which is almost the top right corner. Cesium, on the other hand, is low on electronegativity at 0.7, which explains why it’s relegated to group 1 (bottom left) on the periodic table.
Electronegativity Helps Predict Bond Type
This electronegativity difference, to a great extent, helps determine the kind of chemical bond existing between atoms. For instance, if the electronegativity difference between the two atoms is less than 0.2, the bond is most likely a non-polar covalent bond. If it’s more than 1.5, an ionic bond is quite likely. Anything in between would probably be a polar covalent bond. If both atoms have the same level of electronegativity, then the bond between the two would be considered “pure” covalent bond.