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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In this case, the aluminium ion’s charge rupes “tug” on the electron cloud of iodine, drawing it closer to itself. As the electron cloud of the iodine nears the aluminium atom, the negative charge of the electron cloud “cancels” out the positive charge of the aluminium cation.

Electronic configuration of the cation: From Wikipedia, the free encyclopedia.

Fajans’ Rule – Disclosing Covalent Characteristics in Ionic Bonds

In inorganic chemistryFajans’ rulesformulated by Kazimierz Fajans in[1] [2] [3] are used to predict whether a chemical rlues will be covalent or ionicand depend on the charge on the cation and the relative sizes of the cation and anion. The various types of these interactions span large differences in energy and for the halogens and interhalogens are generally quite small.

Views Read Edit View history. By Fajans’ Rules, compounds are more likely to be ionic if: From the Table below the observed dipole moment of KBr is given as Home Questions Tags Users Unanswered.

How do I ask homework questions on Chemistry Stack Exchange? Note that Fajans’ Rules have been largely displaced by Pauling’s approach using electronegtivites. Comments It is very helpful thak u very much!!! Chemistry Chemistry Articles Fajans Rule. Retrieved from ” https: Larger the charge on the cation, greater is its polarising power. We see that a similar situation occurs, but instead of iodine we now have fluorine, a relatively small highly electronegative atom.


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

Jj Thomson Atomic Theory. The greater is the polarisation produced, more is the neutralisation of the charges and hence the ionic character decreases or the covalent character increases. Here the significant difference between the cations is in their electronic configurations. To use Fajans’ Rules, assume your binary compound is ionic and identify the potential cation and anion.

Fajans’ rules

Compounds are more likely to be covalent if: The “size” of the charge in an ionic bond depends on the number of electrons transferred. Let us consider AlI 3 ; this is an ionic bond which was formed by transfer of electrons.

In this article, we are going to discuss covalent characteristics in ionic bonds. Hence, atoms in a molecule can take up different directional arrangement and thus show structural and stereoisomerism. They are a method for predicting ionic vs. Congratulations You have selected the correct answer!!

This page was last edited on 18 Novemberat 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. This results in synchronised motion of the electrons and an attraction between them.

Fajans Rule | Disclosing Covalent Characteristics In Ionic Bonds

You have selected the wrong answer!! They can be summarized in the following table: In general they increase with increasing atomic number. Take learning on the go with our mobile app.


By using this site, you agree to the Terms of Use and Privacy Policy. Because if this electron cloud of anion is more diffused. 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.

Leave a Reply Cancel reply Your email address will not be published. As the atoms in covalent compounds are held together by the shared electrons ,it is rigid and directional. Chemistry Stack Exchange works best with JavaScript enabled. The large charge pulls on the electron cloud of the iodines. The 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.

Covalent compounds have low melting and boiling point because the molecules in covalent compounds are held together less rigidly. Both a and b. 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.