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Atomic imperfections / point defect When deviations exist from the regular arrangement around an atom or a group of atom in a crystalline substance the defects are called point defects. Types of point defects (A) Stoichiometric defects If imperfection in the crystal are such that the ratio between the cations and the ratio between the cations and anions remains the same as represented by the molecular formula, the defects are called Stoichiometric defects (for CSIR-NET Coaching in Chemistry , JAM Coaching in Chemistry These are 2 types 1. Schottky defects In an ionic crystal of A + B - types equal number of cations and anions are missing from their lattice site so that the electrical neutrality is maintained it is called schottky defects. The schottky defects containing one pair of holes due to missing of one cation and one anion is shown in Fig   Compound exhibiting schottky defects have High coordination number Small difference in size of ca...

Solids can be classified on the basis of nature of order in the arrangement of constituent particles (atoms, ions or molecules) into two types as  1. Crystalline solids 2. Amorphous solids 1 . Crystalline solids (Topic for CSIR-NET Coaching in Chemistry) The substance whose constituent particles (atoms, ions or molecules) are arranged in a defined geometric pattern in three dimensional space are called crystalline solids. X-ray diffraction studies of these crystalline solids reveal that in these solids, the constituents (atoms, ions or molecules) are arranged in a definite orderly arrangement. The regular arrangement of the constituents extends throughout the three dimensional network of crystals. In other words, the crystalline substance are said to have Long range order. This means that in crystalline solids, there is a regular pattern or arrangement of particles which repeats itself periodically aver the entire crystal. In fact a crystalline solid consists of a l...

It was stated in section 6.4 that the products are formed only when reaction molecular come close and collide together at one and the same time. During the collision, molecular rearrangement takes place which leads to the formation of products. For example, a second –order reaction of the types May by traced to a bimolecular collision process involving A and B, and A, respectively. However, the first-order reactions in the gas phase cannot be accounted for by the above collision theory. The first successful explanation of first-order reactions was provided by Lindemann. The mechanism is. (i) A + A ⟺ A* + A                  (rapd equillibrium) (ii) A* ⟶ Products Step (i) involves a rapid equilibrium reaction where in the forward reaction, a molecular A is activated by colliding with another A molecular with a rate constant k1 and in the backward reaction, the excited molecule A is deactivated by colliding with another A mole...

The feasibility of a given reaction can be predicted with the help of their dynamic principles. Besides this the relative amount of reactants and products at equilibrium position of the reaction can also be predicted. In addition, we can predict whether changes in the experimental conditions will increase or decrease the amount of products at equilibrium. However, thermodynamic principles do not provide any information regarding the speed of the given reaction, i.e., how much time a given feasible reaction will take for its completion. Moreover, it is not possible to predict how the speed of a given reaction gets affected by changing the experimental conditions. The study of rate of reaction or by changing the experimental conditions.  The study of rate of reactions including its dependence on the concentration. The important topic of physical chemistry is known as chemical kinetics. The important application of the study of rate of reaction is to use the kinetic data in esta...

The compounds which contain bond between carbon atom and the atoms which are more electropositive than carbon are known as Organometallic compounds. An Organometallic compound contains atleast one direct metal-carbon (M-C) bond, but it is not a rigid condition. The carbon containing groups may be carbonyl, alkyl, alkene, alkyne, aryl, allyl, cyclic, or heterocyclic. This topic is essential for CSIR NET coaching in chemistry . It is also beneficial topic for IIT JAM coaching in Chenistry.  Eg:- (i)  Organo-magnecium compounds  RMgX (Grignard Reagent)  (ii)  Organo-copper compounds   R2CuLi (Gilmann Reagent)  (iii)  Organo –lithium compounds   RLi (R = -Ph, -Bu…..)  Some Important Exceptional Cases:-  Eg:-(1)  Metal carbides and cyanides are not Organometallic compounds i.e. CaC2, NaCN.   Eg:-(2) Wilkinson catalyst  :-It does not contain any M-C bond, even though it is a very important Organometall...

The term polymer is derived from two Greek words: poly means many and mer means unit or part. These are very large molecules having high molecular mass and hence are also called macromolecules. Polymers are macromolecules are very high molecular mass substances each molecule of which consists of a very large number of simple repeating structural unit joined together through covalent bonds in a regular fashion. Thesimple and reactive molecules from which the repeating structural units are derived are called monomers and the process by which these simple molecules i.e.,monomers are converted into polymers is called polymerization. From the exam point of view like CSIR-UGC-NET in Chemistry and GATE in Chemistry, Polymer chemistry is  important branch of chemistry. It is the a key topic for NET Coaching in Chemistry. It is also important for GATE Coaching in Chemistry. Therefore  many questions are asked from Polymer chemistry  in CSIR-UGC-NET in Chemical Scienceand GATE ...

The Atomic Nucleus: The protons and Neutrons are the constituent particles of the Nucleus. There nuclear constituent particular are in general called nucleons which follow the Fermi – Dirac statistics. Ø The nucleus contains Z protons (Z denotes the atomic Number) and N neutrons to give the mass number A (=Z + N). For a particular value of Z, because of the different numbers of N, the isotopes appear. The neutron- proton ratio and their oddness and evenness are very much important in determining the stability of the nucleus. Ø The emission of particles i.e. electrons, from the nucleus does not contradict the proton – neutron model of the nucleus. It is now believed that the trans formation of a neutron into a proton leads to the ejection of a  particle.(Important topic for Chemistry JAM Coaching ) In this proton – neutron model, it is now believed that they are continuously changing one into another through...