CHAPTER:  SOLID STATE- LESSON PLAN

Date:                                                  Class: XII                                       Period Required:07

Gist of Unit /Sub Unit

Activities(Individual or Group)/Demo/ E-class/PPT

èDescribe general characteristics of solid state; è distinguish between amorphous and crystalline solids; èclassify crystalline solids on the basis of the nature of binding forces;  èdefine crystal lattice and unit cell; è explain close packing of particles; èdescribe different types of voids and close packed structures; ècalculate the packing efficiency of different types of cubic unit cells; ècorrelate the density of a substance with its unit cell properties; èdescribe the imperfections in solids and their effect on properties; è Correlate the electrical and magnetic properties of solids and their structure.

èSolids have definite shape and definite volume. The most rigid of the states of matter is solid. Solids can broadly be classified as crystalline and amorphous solids. SOME IMPORTANT TERMS AND CONCEPTS Space lattice and Types of unit cell       Calculation of number of particles per unit cell, Packing Efficiency and radius             Close packing of constituent particles in crystals èCalculation of density of a cubic crystal from its edge IMPERFECTIONS OR DEFECTS IN SOLIDS              Any departure from perfectly ordered arrangement of atoms in crystal is called imperfection or defect We know that ordered arrangement of a solid imparts some unique properties to the solids. Imperfections modify existing properties of a solid and also impart some new properties to the solids. The imperfections can be of two types: Electronic imperfections   ii) Atomic imperfections or point defects Point defects in ionic crystals may be classified into the following three types. Stoichiometric defects  ii)  Non-stoichiometric defects   iii) Impurity defects Electrical, magnetic, dielectric properties of solids èInsulators, Conductors and Semi-conductors with examples èDiamagnetic, Paramagnetic and Ferromagnetic substances with examples

 

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HOME ASSINGMENT	HOTS AND MLL	CO-RELATION WITH OTHER SUBJECTS And extended learning
è Students are given the Home assignment to solve all the in text question solved and unsolved exercises of NCERT. è Exemplar problems for students preparing for competitive examinations. è Compile all questions asked from the chapter in last five years in CBSE board examination. I VSA Question  of  1  mark  each 1) What is the name given to the process of introducing impurities into an insulator to make it semi conductor. Give example. 2) What is the effect of presence of Schottky defect on the density of a crystal? 3) How does temperature influence the conductivity of a semi-conductor? 4) The unit cell of a substance has cations A+ at the corners of the unit cell & the anions B- in the center. What is the simplest formula of compound? 5) What are Dislocations? 6) What is the coordination number of Na+ & Cl- ions in NaCl structure? II  SA Question  of  2  mark  each 7) A body centred cubic element having density 10.3 g/cm3 has a cell edge of 314 pm. Calculate the atomic mass of the element. 8) What type of semiconductor will be formed when (a) Si is doped with As (b) B is doped with Ge 9) If NaCl is doped with 10-3 mol % of SrCl2, what is the concentration of cation vacancies? III SA Question  of  3  mark  each 10) KF has NaCl structure. The density of KF is 2.48 g/cm3. Calculate the distance between K+ & F- in KF. (At. Mass of K = 39, F = 19). 11)  (a) ZnO on heating turns yellow.                (b) What is doping. 1.     With the help of electron spin diagrams, distinguish between ferromagnets, anti-ferromagnets & ferrimagnets. Explain briefly about them.?	VERY SHORT ANSWER TYPE QUESTIONS Q1. Which substance exhibit schottky and Frenkel both defects. Q2. Name a salt which is added to AgCl so as to produce cation vacancies. Q3. Why Frenkel defects not found in pure Alkali metal halide. Q4. What is the use of amorphous silica? Q5. What is the co‐ordination no. of cation in Antifluorite structure? Q6. What is the Co. No. of cation and anion in Caesium Chloride. SHORT ANSWER TYPE QUESTIONS Q1Why common salt is sometimes yellow instead of being of being pure white? Q2. A compound is formed by two elements X and Y. The element Y forms ccp and atoms of X occupy octahedral voids. What is formula of the compound? Q3Explain how electrical neutrality is maintained in compounds showing Frenkel and Schottky defect. Q4 Calculate the number of atoms in a cubic unit cell having one atom on each corner and two atoms on each body diagonal. Q6 In terms of band theory what is the difference between a conductor, an insulator and a semiconductor? Q7 CaCl2 will introduce Scotty defect if added to AgCl crystal. Explain LONG ANSWER TYPE QUESTIONS Q1 In compound atoms of element Y forms ccp lattice and those of element X occupy 2/3rd of tetrahedral voids. What is the formula of the compound? Q2 The density of chromium is 7.2g cm‐3. If the unit cell is a cubic with length of 289pm, determine the type of unit cell (Atomic mass of Cr=52 u and NA = 6.022*1023 atoms mol‐1). Q4. Explain why? (i) Conductivity of metals decreases with increase in temperature. (ii) Conductivity of semiconductors increases with increase in temperature. Q-5 Given that for Fe, a=286 pm; d=7.86g/cm3. Find the type of the cubic lattice to which the crystal of iron belongs to. Also calculate the radius of Fe atom.  Silver crystallizes in the FCC lattice If the edge length of the cell is 4.077 * 10–8 cm and density is 10.5 g/cm3, then calculate the atomic mass of silver.	èRelation with Physics to a great extent.   è PPT available èLectures on Youtube. èBozeman chemistry èX-Ray crystallography and Braggs Law èSuperconductivity

 

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