Which of the beryllium halldes, If any, are considered Ionic compounds?


Which of the beryllium halldes, If any, are considered Ionic compounds?

Fajan's Rule:

Fajan's Rule is a method to predict the nature(ionic/covalent) of a bond using electronegativity & atomic radius data.

The main theme behind Fajan's Rule is inonizability of anion by cation. It works on the theory that some covalent character may be brought into an ionic bond.

The 2 basic statements of this rule are:

{eq}\bullet \text{large cation & a small anion show major ionic bond characteristics (e.g. NaCl)}\\ \bullet \text{small cation & a large anion show major covalent bond characteristics (e.g. }AlI_3)` {/eq}

The reason for this case is that in case of a small cation & a large anion, the high positive charge density on distorts the electron cloud in the anion towards it.

So this way the electron cloud on the anion is shared in a way. So we see the sharing of electrons in the bond which is a characteristic of covalent bond.

Hence the covalent character in the bond.

While in case of a small anion & a large cation, the electron cloud in the anion is too closely held to be distorted by the cation.

Answer and Explanation: 1

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Beryllium generally exists as {eq}Be^{2+} {/eq}. In this form it has high charge density in the ion due to small size of Be.

Thus by Fajan's Rule,...

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Learn more about this topic:

Fajans' Rules for Chemical Bonds


Chapter 8 / Lesson 9

This lesson will talk about polarization of ionic compounds and Fajans' rules. Fajans' rules discuss introduction of covalent character in ionic compounds and how some properties of ionic compounds change because of polarization.

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