IntroductionThe word atom is a Greek word meaning indivisible, i.e., an ultimate particle which cannot be further subdivided. The idea that all matter ultimately consists of extremely small particles was conceived by ancient Indian and Greek philosophers. The old concept was put on firm footing by John Dalton in the form of atomic theory which he developed in the years 1803–1808. This theory was a landmark in the history of chemistry. According to this theory, atom is the smallest indivisible part of matter which takes part in chemical reactions. Atom is neither created nor destroyed. Atoms of the same element are similar in size, mass and characteristics; how
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Some important acids and their structural formula’s.Preparation Manufacture or industrial preparation. (1) HCOOH (Formic acid) (2) (COOH)2 Oxallic acid (3) CH3COOH (Acetic acid) (b) From pyroligneous acid (already discussed in alcohols). (c) Quick vinegar process or fermentation process In the ‘quick vinegar process’, beech shavings, contained in b
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Introduction Atomic Structure:The most special thing about this chapter is that the no. of scientists involved in developed of this concept is remarkably large. Starting with heucippus of Miletus in 440 BC it extends to 2000's. And the research is still going on. Even the great scientist EINSTEIN had his hands in developing this extraordinary concept.Atomic No.: Total no. of protons present in nucleus.Mass No.: Total no. of protons & Neutrons in neucleus.Atomic No.(Z): no. of electrons (when atom is neutral).Mass No.(A): no. of neutrons + no. of protons. Representation Ilustration: Calculate no. of protons, neutrons & electrons in Ans: Z = 3
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OCCURRENCE OF METALS: The earth's crust is the biggest source of metals. Some soluble salts of the metals are also found in sea-water. Metals occur in nature sometimes free but mostly in combined state. The natural mode of occurrence of a metals is largely dependent on its nature. Those metals which are least reactive and have little or no affinity for oxygen, moisture and other chemical reagents occur in free or metallic or native state i.e., in uncombined state. Most of the metals are reactive and hence are found in combined state i.e., as compounds.The natural substances in which the metals or their compounds occur in the earth are called minerals. The
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Term tissue by BICHAT (1771 -1802) [French]Term Histology by Mayer (1819) ''Specialized masses of cell with similar morphology, physiology and embryonic origin. These are developed from undifferentiated cells of the primary germ layers''. Tissues are developed from undifferentiated cells of the primary germ layers though the specialised process of ''cell differentiation''. Earlier it was thought that genetic composition of cell undergoes changes in such a way that one daughter cell inherits different set of genes from other daughter cells i.e., some of the genes are lost during the process. But, today from experiments i
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Hydrogen bond is formed when a slightly positive hydrogen atom, attached covalently to strong electronegative atom A (e.g., F, O or N) is held by a non-bonded electron pair of another atom B. The coordination number of hydrogen becomes two and it acts as a bridging atom between A and B.Generally hydrogen bond is formed with only F, O and N atoms. Sometimes less electronegative atoms such as Cl, S etc., also take part in the formation of hydrogen bond. Hydrogen bond is denoted by dotted lines (...........). It can be defined as :The attractive force that binds a hydrogen atom, which is already covalently attached with strongly electronegative atom of gain element
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Aldehydes & Ketones:Aldehydes and ketones contains the same functional group, the carbonyl group (> C = O).Aldehydes behave as reducing agents due to presence of reducing hydrogen atom where as ketones have no such property so aldehydes easily reacts with oxidising agent. Even HCOOH shows some properties of carbonyl compounds due to presence of – CHO group. HCOOH behaves as reducing agent while in other acids no reducing hydrogen atom, so no reaction with oxidising agent. Preparation Methodology:(i.) Oxidation of Alcohols:(a.) From PCC or pyredeniumchlorochromate. Which is pyridine, CrO3 and HCl, in equal ratioBy Jones reagent (CrO3 and aq. CH3COCH3) r
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Introduction to Ether & Epoxides:We know alcohols family with their rich chemical reactivity but ethers - compounds containing a R-O- R unit are less reactive and gives relatively few chemical reactions. This lack of reactivity of ether makes them valuable as inert solvents in a number of chemical reactions.Unlike most ethers, epoxides – compounds in which the C – O – C unit forms a three-membered ring - are very reactive substances due to molecular strain.Ethers are defined as symmetrical or unsymmetrical depending on whether the two groups bonded to oxygen are the same or different. Unsymmetrical ethers are also called mixed ethers. Dimethyl
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AIPMT 2008 Unveiled! - courtesy Answer Keys Solved Papers Examination Aalysis addthis_pub = 'pankajvermani'; AIPMT 2008 Examination Paper Solutions 1. Which two of the following five physical parameters have the same dimensions? (a) energy density (b) refractive index (c) diele
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AIPMT 2008 Unveiled! - courtesy Answer Keys Solved Papers Examination Anaysis addthis_pub = 'pankajvermani'; AIPMT 2008 Examination Paper Solutions 1. Which two of the following five physical parameters have the same dimensions? (a) energy density (b) refractive index (c) dielectric co
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These presentations are a unique way of discovering your subject topis - Interesting insights, great problems and a stepwise approach. These unique presentations are intended to help you understand your concepts like never before. Every screen has problems which will help you understand the concept and its application. Try to solve every problem, before actually peaking on the answer :) *best viewed on macromedia flash version 9
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Organic Chemistry Quick Fact Sheet Acidic power Order Why ? 1. III < II < I Farther the (–I) group (Cl), lesser the acidic strength 2. I < II < III Farther the (+I) group, greater the acidic power 3. II < I < III —CH3 is electron donating and— NO2 is electron attracting 4. II < I < III —CH3 is electron repelling; de
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A New BeginningA new session is starting for JEE, new people are coming... selected ones are planning for IIT Days..... people are planning to repeat or waiting for other results.... its too much action out there AND I am sitting and writing for you. Sometimes I still miss those JEE preparation days, it was a fun life.... when every new question was a challenge, every solved question was recorded as an achievement.Anyways...gone is gone, lets talk about you people. You people are staring for JEE preparation. Its a crucial step, one wrong decision at this time and you will be studying in tesion, stress and fear. At this time, choosing coaching institute, books, accom
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It is TIME!! I think this is my last post for your friends before this IIT JEE. By now most of you are done with your coursework and revising day and night. I am not gonna talk about revision strategy but in this last post I'd like to share something that can help you to get best output of your preparation. First thing first, JEE is almost at your doorstep, you have done your part of studies, time has gone... so just don't think about what you did and what you could have done. Till the final day try to keep your calm, dont panic and .. wo kya kahte hain na... just
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ALL INDIA TEST SERIES THIS SUNDAY -- "Sorry, I have to study" !!"So, how much did you score in all india maths open test ? ""Well... I did not appear in the exam.""Oh... Ok... WHAAAATTTTTT???" "I said i did not appear in the exam.""But why ??""Well... I have not covered Co-ordinate section yet and the exam was focused on that only. I would have wasted my time there.""You know what...... YOU ARE NUTS"This kind of conversation I faced many times when I was preparing for JEE. In those days all india engineering test series were big and I am sure they are even bigger these days. Years
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Hey Friends,Years back, one day i woke up and decided that I am gonna fight for prestigious IIT JEE entrance. But didn't know how. Only coaching institutes were the only hope. At that time something like goIIT.com was not there in anyone's mind. So I must say friends, you are lucky. Let's see how goIIT can help you in the best possible manner.Since last few months I am writing answers to your queries. Most of the people have same questions, I had them too when I was in IIT JEE Preparation . While studying me and my best friend "Mechanicals" developed few practices which put both of us ahead of many people (we both scored good ranks in IIT). So
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ChapterOrganometallic compounds are compounds that contains a carbon metal bond. You are already familiar with some organometallic compound like sodium acetylide (NaC==CH) and alkyl lithium which has an ionic bond between carbon and sodium or carbon and lithium. But simply having a metal and carbon in the same compound is not sufficient for classification as organometallic. Sodium methoxide (NaOCH3), for example, is not an organometallic compound ; sodium is not bonded directly with carbon atom.Preparation of organomagnesium : Grignard ReagentsThe most important organometallic reagents in organic chemistry are organomagnesium compounds. They are called Grignard reag
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ChapterMechanism of bimolecular (SN2) nucleophilic substitution [Mechanism & Kinetics] An SN2 reaction proceeds with complete stereo chemical inversion.SN2 reaction decreases with stearic hinderance and increases by presence of nonprotic solvent for example DMF and DMSO. SN2 reaction decreases in the presence of protic solvent like CH3OH, C2H5OH, HF etc.As the size of alkyl group increases than chemical reactivity towards SN2 decreases.As the size of alkyl group increases sterichindrance comes into play so reactivity decreases.
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