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 deciding factor must be the cation. For high charge, small cation will have more polarizing power. Hence covalent character increases.

This explains why for the common halides, iodides, are the most covalent in nature I – pm. This question appears to be off-topic. Here the significant difference between the cations is in their electronic configurations. Views Read Edit View history.

Fajans’ Rule – Disclosing Covalent Characteristics in Ionic Bonds

Since there are no free ions in covalent compounds to conduct electricity, they are bad conductors of electricity. What is Fajans rule? Two contrasting examples can illustrate the variation in effects. 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. If the anions were different, then the answer could be affected by the variation of the anion.

Whilst not strictly true for heteronuclear molecules it does provide a simple qualitative method for predicting the bond character. The covalent character is found in compounds which have high polarizing cation and high polarizable anion. Congratulations You have selected the correct answer!!


By Fajans’ Rules, compounds are more likely to be ionic if: 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.

In inorganic chemistryFajans’ rulesformulated by Kazimierz Fajans in[1] [2] [3] are used to predict whether a chemical bond will be covalent or ionicand depend on the charge on the cation and the relative sizes of the cation and anion. Where as larger is the size of anion, more will be the polarization of anion. Covalent compounds have low melting and boiling point because the molecules in covalent compounds are held together less rigidly.

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bond – What is Fajans rule? – Chemistry Stack Exchange

Electronic configuration of the cation: Login to track and save your performance. Practise s of questions mapped to your syllabus.

Fajans’ rules note the difference were formulated in by Kazimierz Fajans. From the Table below the observed dipole moment of KBr is given as The greater is the polarisation produced, more is the neutralisation of the charges and hence the ionic character decreases or the covalent rulees increases.

When two non-polar molecules approach, attractions or repulsions between the electrons and nuclei can lead to distortions in their electron clouds i.


In this article, we are going to discuss covalent characteristics fajabs ionic bonds.

CHEM Polarizability

The large charge pulls on the electron cloud of the iodines. A cation having inert gas like configuration has less polarising power in comparison to cation having pseudo-inert gas like configuration. The covalent compounds exist in all the three states i. In this case, the aluminium ion’s charge will “tug” on the electron cloud of iodine, drawing it closer to itself. Die Eigenschaften salzartiger Verbindungen und Atombau”.

These compounds are molecular in nature and not ionic, their reactions are molecular and proceed at a much slower rate than those of ionic compounds.

This results in synchronised motion of the electrons and an attraction between them. Note that Fajans’ Rules have been largely displaced by Pauling’s approach using electronegtivites. As the atoms in rukes compounds are held together urles the shared electrons ,it is rigid and directional.

If two cations have the same size and charge, then the one with 18 electrons in the outermost shell has greater polarising power than the other with 8 electrons in the outermost shell. From Wikipedia, the free encyclopedia. Larger the charge on the cation, greater is its polarising power.

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