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 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.

You have selected the wrong answer!! Let us consider Fajqns 3this is an ionic bond which was also formed by transfer of electron. Non Biodegradable Waste Management. On average the electron cloud for molecules can be considered to be spherical in shape.

When two molecules are close together, the instantaneous dipole of one molecule can induce a dipole in the second molecule. However, the remnants of Fajans’ Rules are found in Hard-Soft Acid-Base Theorywhich predicts bonding properties based on polarizability which is based on size and charge.

Fajans’ rules

Your email address will not be published. A cation having inert gas like configuration has less polarising power in comparison to cation having pseudo-inert gas like configuration.

Two contrasting examples can illustrate the variation in effects. When more molecules interact these induced dipoles lead to intermolecular attraction. 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.


Gas To Solid Is Called. How do I ask homework questions on Chemistry Stack Exchange? 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.

Fajans’ rules – Wikipedia

Thus it can be seen that while HI is essentially covalent, HCl has significant ionic character. Now, if we take a different example, for example AlF 3 Aluminium Fluoride. Larger the charge on the cation, greater is its polarising power. The percentage of ionic character in a compound can be estimated from dipole moments. In this case, the aluminium ion’s charge will “tug” on the electron cloud of iodine, drawing it fajana to itself.

That positive charge then exerts fajanx attractive force on the electron cloud of the other ion, which has accepted the electrons from the aluminium or other positive ion.

Hence covalent character increases. The ability of a cation to distort an anion is known as its polarization power and the tendency of the anion to become polarized by the cation is known as its polarizability. 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.


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. Login to track and save your performance.

Both a and b. Die Eigenschaften salzartiger Verbindungen fajanx Atombau”. Home Questions Tags Users Unanswered. If the anions were different, then the answer could be affected by the variation of the anion.

In reality, every bond has some covalent as well as ionic characteristics. Compounds are more likely to be covalent if: Thus, we get an ionic compound metal bonded to a nonmetal with slight covalent character. Covalent compounds have low melting and boiling point because the molecules in covalent compounds are held together less rigidly. Retrieved from ” https: This page was last edited on 18 Novemberat Whilst not strictly true for heteronuclear molecules it does provide a simple qualitative method for predicting the bond character.

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

Comments It is very helpful thak u very much!!! The deciding factor must be the cation. Chemistry Chemistry Articles Fajans Rule.

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