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Electronegativity

Electronegativity is the propensity of an atom in a molecule to draw the shared pair of electrons toward itself.

  • Because it is merely a propensity, this attribute has no dimensions.
  • It essentially represents the final consequence of atoms‘ propensities to attract electron pairs that form bonds in various elements.
  • On several scales, we quantify electronegativity. Linus Pauling created the most widely used scale.
  • The least electronegative element is cesium, which has a value of 0.7, and the most electronegative element is fluorine, which has a value of 4.0.
  • According to the importance of chemistry, electronegativity will be regarded as the primary factor in chemical bonding and is a significant quantity in defining the nature of bonds between elements.
  • In the modern periodic chart, electronegativity increases across a period as we move from left to right because nuclear charge increases and atomic size decreases.
  • The periodic table’s electronegativity trend, for instance, is shown below for period 3.
  • As we travel down the group in the current periodic table, the atomic number rises.
  • Although the nuclear charge likewise rises, the effect of the rise is mitigated by the addition of one shell.
  • As we descend the group, electronegativity’s value drops.
  • For instance, the electronegativity value drops in the halogen group as we proceed from fluorine to astatine, as illustrated in the diagram below.
  • A general observation is that metals exhibit lower electronegativity values than non-metals.
  • As a result, the nature of metals and non-metals is electropositive and electronegative, respectively.
  • Due to their tiny size and greater electronegativity values, the elements in period two have different properties from the elements in their respective groups.
  • The second period’s features are similar to those of the following group in period three.
  • This is brought on by a little discrepancy in their electronegativities. As a result, a diagonal relationship develops.

Elements that are Most and Least Electronegative

  • The periodic table’s most electronegative element is fluorine. It has an electronegativity of 3.98.
  • The least electronegative element is cadmium. It has an electronegativity of 0.79.
  • Cesium is the most electropositive element because electro positivity is the exact opposite of electronegativity.
  • The most electronegative elements are those with the fewest inner electron shells between the positive nucleus and the valence electrons and the fewest required electrons to complete their valence shells.
  • Fluorine is the most electronegative of all the elements. It has a 4.0 electronegativity. Electronegativities for metals are less than 2.0.
  • With electronegativity values of 0.7, cesium (Cs) and francium (Fr) are the least electronegative elements.

Electronegativity’s Effect on Covalent Bonding

  • The electronegativities of the two bound atoms have a significant impact on the covalent bond’s strength (especially the difference in the electronegativities of the bonded atoms).
  • Homonuclear diatomic molecules have relatively “pure” covalent bonds because the bound atoms’ electronegativities match (resulting in the bonded pair of electrons being almost equidistant from the two bonded nuclei).
  • H2 molecules, Cl2 molecules, and O2 molecules are only a few examples of these covalent linkages in nature.
  • On the other hand, polarization often occurs in covalent bonds between two species with different electronegativities.
  • This happens as a result of the more electronegative atom drawing the bond pair of electrons closer to itself, which results in the development of a partial negative charge (often represented by the symbol -).
  • The more electropositive atom also develops a partial positive charge, represented by the symbol +, at the same moment. The polarity of the chemical connection is caused by these partial charges.

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