Electronegativity is linked to the attractiveness of atoms.
Electronegativity is the ability of an atom to attract electrons to itself when combining with another atom in a chemical bond . The greater the electronegativity, the greater the attraction capacity.
This tendency of atoms is linked to their electroaffinity and their ionization potential . The most electronegative atoms are those that have a negative electronic affinity and a high ionization potential, which allows them to conserve their electrons against the attraction that comes from the outside and, in turn, attract the electrons of other atoms to themselves.
Electronegativity scale
Electronegativity values are based on thermochemical data. The best-known scale was proposed by the American chemist Linus Pauling (1901-1994), winner of the Nobel Prize in Chemistry in 1954. On the Pauling scale , the element with the lowest electronegativity is cesium with 0.7 , while the element The highest electronegativity is fluorine with 4 .
In this list or table we also find other elements that have a low electronegativity, such as potassium and rubidium with 0.82, barium and radium with 0.89, and sodium with 0.93.
On the contrary, among those that have the highest, in addition to the aforementioned fluorine, we find elements such as oxygen with 3.44, chlorine with 3.16, nitrogen with 3.04 and bromine with 2, 96.
Link Types
When two atoms whose electronegativities are very different from each other join together, an ionic bond is established. On the other hand, when atoms have similar electronegativities, a polar covalent bond is formed, with the most electronegative atom remaining with the negative charge.
Depending on electronegativity, atoms can establish ionic bonds or polar covalent bonds.
It should be noted that electronegativity is not an atomic property in the sense that it varies depending on the context: it depends on the atom in the framework of a molecule . On the contrary, electroaffinity or electronic affinity is associated with an isolated atom (it is the energy that an atom releases at its lowest energy level when it takes an electron and establishes a mononegative ion).
Other characteristics of electronegativity
In addition to everything indicated, we cannot ignore another series of relevant aspects about electronegativity, such as the following:
-The electronegativities of the elements increase from bottom to top within each group, while they increase from left to right within the different periods.
-According to Pauling, electronegativity depends on what the oxidation state is.
-In the aforementioned Pauling scale, the values become indexes, that is, they do not have unity.
-Other relevant figures who spoke about electronegativity were AL Allred and EG Rochow. These came to make it clear that for them that was the force of attraction that existed between an electron in a bonded atom and a nucleus.
-RS Mulliken also addressed the topic at hand. In his case, he made it clear that the electronegativity of an element can be determined by averaging the electron affinity and ionization energy of its valence electrons.