Packing Fraction||Efficiency||Percentage OF void space||Coordination Number|| Description OF Cube|| Contribution OF Atom present at different location in a Cube||Class Illustrations with Short Tricks

Non - Existence OF End - Centered Cubic Cell || Description OF Cube || Contribution OF Atom Present at Different Location in a Cube || Different types OF Cubic unit Cell || Simple Cubic Cell || Body Centered Cubic Cell |Face Centered cubic Cell

Description OF Periods (all seven periods) || Maximum Number OF Elements in Given Period (short trick to remember) || Class Illustration with Short Tricks

Molecular Mass || Gram Molecular Mass || Number of Moles || Number of Molecular Atomicity || Class Illustration with Short Tricks

Molality|| PPM|| PPB||Relation between Molality and Molarity|| Relation between Molality and Mole Fraction|| Relation between Molarity and Percentage W/W||Class Illustrations with Short Tricks

Calculation Of The Contribution Of Atoms Present At Different Lattice Sites|Calculation Of Number Of Atoms|Close Packed Structures|Close Packing in Two Dimensions|Close Packing in Three Dimensions|Summary

A mineral having the formula AB_(2) crytallises in the cubic close-packed lattice, with the A atoms occupying the lattice points. What is the coordination number of the A atoms and B atoms ? What percentage fraction of the tetrahedral sites is occupied by B atoms ?

In a close packed structure, the atoms stack together occupying maximum space and leaving minimum vacant space. The close packing arrangment may be hcp (ABABA….) or ccp (ABCABCA….). In these arrangments, there is one octahedral void and two tetrahedral voids. Depending upon the ratio of size of cation and anion, the ions of one type occupy the voids of other ions. This results in different types of crystalline structures. A metal crystallises into two cubic phases, fcc and bcc. Which phase has lesser packing efficiency and how much ?

Which of the following statements is/are correct about hexagonal close packing ? 1. The coordination number is 8 2. It is ABAB type packing in which third layer is aligned with the first layer 3. Be, Mg, Mo etc. are found to have hcp structure 4. In hcp, atoms occupy 74% of the available space

In the crystalline solids the smallest repeating part in the lattice is known as unit cell. The unit cells are described as simple (points at all corners), body centred (points at all the corners and it the centre), face centred (points at all the corners and centre of all faces), and end centred (points at all hte corners and centres of two opposite and faces) unit cells. In two common tyupes of packing ccp and hcp, 26% of space is left unoccupied in the form of interstitial sites. For the stable ionic crystalline structures, there is difinite radius ratio limit for a cation to fit perfectly in the lattice of anions, called radius ratio rule. This also defines the coordination number of an ion, which is the number of nearest neighbours of opposite charges. This depeds upon the ratio of radii of two types of ions, r_(+)//r_(-) . This ratio for coordination numbers 3,4,6,and 8 is respectively 0.155 - 0.225, 0.225 - 0.414, 0.414 - 0.732 and 0.732 - 1 respectively. In a cubic lattice of XYZ, X atoms are present at all corners except one corner which is occupied by Y atoms. Z atoms are present at face centres . The formula of the compound is