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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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Hence covalent character increases. In reality, every fajsns has some covalent as well as ionic characteristics. Where as larger is the size of anion, more will be the polarization of anion.

Fajans’ rules

Practise s of questions mapped to your syllabus. Larger the charge on the cation, greater is its polarising power. Compounds are more likely to be covalent if: The polarizing power and polarizability that enhances the formation of covalent bonds is favoured by the following factors: When the melting points of two compounds are compared, the one having the lower melting point is assumed to have the smaller degree of ionic character. Jj Thomson Atomic Theory.

This question appears to be off-topic. If the anions were different, then the answer could tules affected by the variation of the anion. We see that a similar situation occurs, but instead of iodine we now have fluorine, a relatively small highly electronegative atom.

As the atoms in covalent compounds are held together by the shared electrons ,it is rigid and directional.

Because if this electron cloud of anion is more diffused. Ffajans changes seen in the variation of MP and BP for the dihalogens and binary interhalogens can be attributed to the increase in the London dispersion forces of attraction between the molecules.


Fajan’s Rules | Chemical Bonding and Molecular Structure, Chemistry, Class 11

Fqjans configuration of the cation: Practise This Question The acid formed when sulphur trioxide reacts with water is. 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. What is Fajans rule? From the Table below the observed dipole moment of KBr is given as When a cation approaches an anion, the electron cloud of the anion is attracted towards a cation and hence gets distorted.

In the case of aluminium iodide an ionic bond with much covalent character is present. They are a method for predicting ionic vs.

They can be summarized in the following gajans Home Questions Tags Users Unanswered. Your email address will not be published. To use Fajans’ Rules, assume your binary compound is ionic and identify the potential cation and anion.

The ionic character arises from the polarizability and polarizing effects of H and I. Note that Fajans’ Rules have been largely displaced by Pauling’s approach using electronegtivites.

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.

Now, if we consider the iodine atom, we see that it is relatively large and thus the outer shell electrons are relatively well shielded from the nuclear charge. The fluorine’s electron cloud is definitely less shielded from the nuclear charge and will thus be less polarizable. What Is Valence Bond Theory. Chemistry Stack Exchange works best with JavaScript enabled. The polarising power of the cation and the polarisability of the anion and hence the formation of covalent bond depends on:.


The faans charge pulls on the electron cloud of the iodines.

Views Read Edit View history. Non Biodegradable Waste Management. This page was last edited on 18 Novemberat Now, if we take a different example, for example AlF 3 Aluminium Fluoride. They are generally soluble in organic solvents but insoluble in water and other polar solvents. In this article, we are going to discuss covalent characteristics in ionic bonds. In general they increase with increasing atomic number.

Fajans’ Rule – Disclosing Covalent Characteristics in Ionic Bonds

Comments It is very helpful thak u very much!!! The percentage of ionic character in a compound can be estimated from dipole moments. Let us consider AlI 3 ; this is an ionic bond which was formed by transfer of electrons. This makes the anion easily polarizable. They usually consists of molecules rather than ions. This explains why for the common halides, iodides, are the most covalent in nature I – pm.

Hence, atoms in a molecule can take up different directional arrangement and thus show structural and stereoisomerism.