Name: Radius Ratio and Coordination Number
Uploaded: 2019-07-19
Duration: 3 min 49 s
Description: The radius ratio plays a very important role in the determination of a structure in an ionic crystal. Watch the video to know more about the radius ratio of...

Question

Draw the structure of

NaCl

and represent the coordination numbers of

{Na}^{+}

and

{Cl}^{-}

ions in the diagram.

Accepted Answer

Rock Salt structure (Structure of $NaCl$ ): The formation of $NaCl$ crystal can be explained in the following manner. The two ions form one ion-pair of opposite charges by the electrostatic force of attraction. Each of the ions has a strong residual field around it and will naturally attract another ion-pair much in the same way as two magnets attract each other, i.e., a cluster is formed. Two clusters combine together to give a unit cell. Finally, large number of unit cells unite together to form three-dimensional cubic crystal.

Filling up of ion pairs in stages: (A) shows an ion-pair, (B) two ion-pairs and(C) four ion-pairs of sodium chloride

In $NaCl$ crystal , each ${Na}^{+}$ ion is surrounded by six ${Cl}^{-}$ ions at the comers of a regular octahedron and similarly each ${Cl}^{-}$ ion is surrounded by six ${Na}^{+}$ ions. It is, therefore, termed as $6$ arrangement. The radius ratio $[r_{Na}^{+} / r_{Cl}^{-} = 0.95 / 1.81 = 0.524]$ suggests that coordination number of each ion is six.

Unit cell representation on $NaCl$ structure
In the octahedral structure ${Cl}^{-}$ ions may be regarded as having a cubic closed packed $(ccp)$ arrangement in which all octahedral holes are filled by ${Na}^{+}$ ions.

Draw the structure of $NaCl$ and represent the coordination numbers of ${Na}^{+}$ and ${Cl}^{-}$ ions in the diagram.

Important Questions on States of Matter: Solid State

Learn and Prepare for any exam you want !

Draw the structure of NaCl and represent the coordination numbers of Na+ and Cl- ions in the diagram.

Important Questions on States of Matter: Solid State

Learn and Prepare for any exam you want !

Draw the structure of $NaCl$ and represent the coordination numbers of ${Na}^{+}$ and ${Cl}^{-}$ ions in the diagram.