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The trend of attaining covalent character by ionic compounds as a consequence of polarisation may be generalized in terms of Fajan’s rule. According to this. Fajans’ Rule for the prediction of relative nonpolar character. Electrostatic forces in a crystal Learn Fajans’ Rule by Disclosing Covalent Characteristics in Ionic. Fajan Rule: Greater is the polarization, greater is the covalent character. | Online Chemistry tutorial IIT, CBSE Chemistry, ICSE Chemistry, engineering and.

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The polarizing power and polarizability that enhances the formation of covalent bonds is favoured by the following factors: For high charge, small cation will have more polarizing power. In reality, every bond has some covalent as well as ionic characteristics.

From an MO perspective, the orbital overlap disperses the charge on each ion and so weakens the electrovalent forces throughout the solid, this can be used to explain the trend seen for the melting points of lithium halides.

Home Questions Tags Users Unanswered. From the Table below the observed dipole moment of KBr is given as Views Read Edit View history. Congratulations You have selected the correct answer!! This explains why for the common halides, iodides, are the most covalent in nature I – pm.

bond – What is Fajans rule? – Chemistry Stack Exchange

To picture how this occurs, compare the situation 1 where the electrons are evenly distributed and then consider 2 an instantaneous dipole that would arise from an uneven distribution of electrons on one side of the nucleus.


Login to track and save your performance. Thus, we get an ionic compound metal bonded to faajns nonmetal with slight covalent character. The deciding factor must be the cation.

Fajans’ rules

To use Fajans’ Rules, assume your binary compound is ionic and identify the potential cation and anion. Leave a Reply Cancel reply Your email address will not be published.

Practise This Question The acid formed when sulphur trioxide reacts with water is. This results dajans synchronised motion of the electrons and an attraction between them.

From this it is possible to calculate a theoretical dipole moment for the KBr molecule, assuming opposite charges of one fundamental unit located at each nucleus, and hence the percentage ionic character of KBr. This produces an ionic bond with covalent character. Here the significant difference between the cations is in their electronic configurations.

Note that Fajans’ Rules have been largely displaced by Pauling’s approach using electronegtivites. Now, if we take a different example, for example AlF 3 Aluminium Fluoride. The users who voted to close gave this specific reason: The ionic character arises from the polarizability and polarizing effects of H and I. Let us consider AlF 3this is an ionic bond which was also formed fajanns transfer of electron.

As the atoms in covalent compounds are held together by the shared electrons ,it is rulss and directional. In this article, we are going to discuss covalent characteristics in ionic bonds.

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On the left, the cation charge increases size decreases and on the right, the anion size increases, both variations leading to an increase in the covalency. Hence, atoms in a molecule can take up fajqns directional arrangement and thus show structural and stereoisomerism.

They are derived from momentary oscillations of electron charge in atoms and hence are present between all particles atoms, ions and molecules. This makes the anion easily polarizable. In the time with the help of X-ray crystallography, he was able to predict ionic or covalent bonding with the attributes like ionic and atomic radius. The fluorine’s electron cloud is definitely less shielded from the nuclear charge and will thus be less polarizable.

It is found that the greater the possibility of polarization, the lower is the melting point and heat of sublimation and the greater is the solubility in non-polar solvents. Fajans’ rule states that a compound with low positive charge, large cation and small anion has ionic bond where as a compound with high positive charge, small cation and large anion are covalently bonded.

Retrieved from ” https: Hence covalent character increases. What Is Valence Bond Theory. Take learning on the go with our mobile app. Both a and b.