Knowledge Booster

BEAGG'S EQUATION   W. L. Bragg & W. H. Bragg the two  scientists has given this equation.  Derivation of Bragg Equation : •  इस diagram के अनुसार क्रिस्टल के एक पुंज को आपतित कोण ( glancing angle) थीटा (Q) पर गिराया गया।  •  क्षैतिज रेखाएँ KL & MN क्रिस्टल मे दो उत्रोतर Atomic तलों को व्यक्त करती है।  •  KL & MN दोनों एक दूसरे से d distance पर हैं।  •  AB & CD incident and reflected X-rays पर खींचे perpendicular(लंबवत) plane(तल) हैं।  •  Incident and Reflected bunch(पुंज) पर EG & EH perpendicular plane खींचे जाने पर दोनो पुंजों (bunches) की path distance   = GF + FH •  इसकी value wave length का पूर्ण गुणांक (n) होना चाहिए,           n = order (1,2,3....)  Laimda = wave length of rays d = distance between layers of atoms in a crystal.                             ...

CUBIC UNIT CELL •  Relation between edge length and radius : •  Edge length of unit cell is measured from one corner lattice point to adjacent corner.  •  all the constituent particles are considered as solid sphere with radius ' r'. SIMPLE CUBIC UNIT CELL •  Relation between edge length and radius : •  In this unit cell the adjacent corner atoms touch each other.  •  [ a = 2x ] BODY-CENTRED CUBIC UNIT CELL •  Relation between edge length and radius: •  In this unit cell the adjacent corner atoms do not touch each others.  •  all corner touch the atom at body centred.  •  [ Fd = √2 a ] FACE-CENTRED CUBIC UNIT CELL •  In this unit cell the adjacent corner atoms do not touch each other.  •  all atoms touch the atom at face centred.                           THANK YOU  !          ...

VARIATIONS WITHIN A CRYSTAL SYSTEM :  A. Primitive Unit Cells/Simple Unit Cells(PC/SC) : When constituent particles are present only on the corner positions of a Unit cell, it is called a simple.  Example : Cubic, Tetragonal, Orthorhombic, Monoclinic, Triclinic, Hexagonal, Rhombohedral or Trigonal.  Calculation :                        •  Effective number of atoms per unit cell  • Contribution of an atom in the unit cell = (1/8)th of atom.  So,  Formula :      { Effective no. of atoms = Corners of cubic×contribution of an atoms in one unit cell}               8×1/8 = 1 answer.  B. Body-Centred Cubic(BCC) : Such a unit Cells contains one constituent particles (atom, molecule, ion) at its body centre besides the ones that are it's corners.  Example : Cubic, Tetragonal, Orthorhombic.  Calculation ...

CRYSTAL SYSTEMS There is seven types of Crystal system: 1. Cubic  2. Tetragonal 3. Orthorhombic 4. Monoclinic 5. Triclinic 6. Hexagonal 7. Rhombohedral or Trigonal "Crystal systems are defined based on 'Parameters' of a Unit cell :  A unit cell is characterized by six parameters.  a, b, c = edge length alpha, beta, gama = angles • Alpha(L) : angles lies between edges b & c.  • Beta(B) : angles lies between edges a & b.  • Gama(Y) : angles lies between edges a & b.  Parameters are in various Crystal system : The following chart are defined that parameters of various Crystal system.  Variations within a Crystal System: Following types of variations we can see in the Crystal system.  A. Primitive Unit Cells/Simple Unit Cell(PC or SC)  B. Body-Centred Unit Cell(BCC)    C. Face-Centred Unit Cell(FCC)  D. End-Centre...

CRYSTALS/CRYSTALLINE A constituents are arranged A highly ordered microscopic structure,forming a crystal lattice that extend in all directions.                 Fig. 1 : Crystal CLASSIFICATION OF CRYSTALS : These are four types of crystals are following :  1. Ionic Crystals : It is binding by ionic        bonds.               Fig. 2 : (NaCl)  Properties/characteristics of Ionic Crystals :  •  It is hard and brittle.  • High melting point.  • High heat of fusion.  • Poor thermal and electric                      conductors.  Example : NaCl, PbS. etc.  2. Molecular Crystals :   It is binding            by  Vander waal's forces ( London dispersion, dipole-dipole force, hydrogen bonds).    ...

ANISOTRPOPY It is the property of substance to show variations in physical properties along different moleculer axis. It is opposite of isotropic materials " अनिसोट्रॉपी एक सामग्री की संपत्ति है जो इसे अलग-अलग दिशाओं में अलग-अलग गुणों को बदलने या ग्रहण करने की अनुमति देती है जैसा कि आइसोट्रॉपी के विपरीत है। " Example : Which all material/substance who can adjust their size and shape as per requirement.  ALLOTROPES When a substance/matter exists in two or more forms then they call allotropes.  Example : Diamond and graphite are allotropes of carbon.  POLYMORPHISM When a single substance crystallized in two or more forms under different conditions of solidification is called polymorphism and the crystal showing polymorphism are called polymorphous .   Example : Silica forms many polymorphous such as alpha, bita- quartz, tridimite, crystobatic, coesite.  ISOMORPHISM Iso = Same or identical Morph = Shape or Forms When...

General Introduction of Solid State "Solid is the one of four fundamental states of matter. The particles(atom, molecules, or ions)in solid state are closely packed together and contain the least amount of kinetic energy." Characteristics of Solid state • Particles distance is minimum.  • Size,volume, mass, and shape are absolute.  • Density is greater than gas and liquid states • Moving character are less than liquids and gases.  • Solids are heavier than liquids and gases. ( exception ice is lighter than water)  • Particles are bound strongly by intramolecular forces.  Classification of solid state  On the basis of the nature of order present in the arrangement of their constituent particles.  A- Crystalline Solids It is a solid whose particles posses a regular order a long range arrangement.        Fig. 1:  arrangement of crystalline                     ...

Latice Energy  It is defined as the Energy required to completely seperate one mole of liquid ionic Compounds into gaseous constituent ions.  E.g. NaCl,      ∆H (lattice) = 788 kj/mol        Factors affecting Lattice Energy(U)  • Interionic distance.  • Charge on ions. 

" The attractive force which holds various constituents together in different chemical species is called Chemical bonding "   Types of Chemical bonding -  1. Ionic Bond - The bond formed as a result of electrostatic attraction between the positive(+ve) and negative(-ve) ions is called electrovalent or Ionic Bond.  2. Covalent Bond - One or more pairs of electrons are shared by the two atoms. Langmuir introduced the term of covalent bond in 1919.  These are two type of covalent bond is following: • Polar Covalent Bond   -   The bonding electrons shared unequally between two atoms partial charges on atoms.   Example: H2O, HCl, PCl3, PCl5. (The central atom attracts molecules more strongly than surrounding atoms)  • Non-Polar Covalent Bond -  The bonding electrons shared equally between two atoms. No charges on atoms.  Example: Cl2, H2, O2, N2, F2  • Co-ordinate Bond -  It is also known as Dative   Bond. The...

"It is a value that is used when describing the energy level available to atoms and molecules". There are four quantum numbers as following :- • Principle Quantum Number- The energy of electrons in an atom depends on principle quantum number. It is denoted ' n '. The principle quantum no.determines the energy of electron and size of the shell.  n= 1,2,3,4,5...... Electron shell= K, L, M, N, O......  Object of principle quantum number, it gives us the energy and radial distance.  • Azimuthal Quantum Number- It is the quantum no.for an atomic orbital that determines it's angular momentum and describes the shape of the orbital,  it is also know as Orbital Quantum Number. Denoted by ' l'. Object it gives us the magnetude of angular momentum of electron.  • Magnetic Quantum Number- It is deals with the direction of angular momentum  with respect to some fixed derection in space(that is the direction  along with a magnetic field is applied). It is denoted by...