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Topic : chemistry
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1
1089
Engineering Entrance
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JEE Main
EQUILIBRIUM BASICS Equilibrium is a pretty easy topic. Big name, but easy idea. First, when you have a system made up of a bunch of molecules, those molecules sometimes combine. That's the idea of a chemical reaction. Second, a chemical reaction sometimes starts at one point and moves to another. Now imagine the reaction finished and you have a pile of new chemicals. Guess what? Those chemicals want to go through a reverse chemical reaction and become the original molecules. We don't know why. Sometimes they just do. Put those two ideas together and you have equilibrium. 1. Two reactants combine to make a product. 2. Products like to break apart
Topic : EVERY THING ABOUT MOLECULAR SHAPES........IIT
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12
834
Engineering Entrance
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JEE Main
Molecular Shape The Shape of Molecules The three dimensional shape or configuration of a molecule is an important characteristic. This shape is dependent on the preferred spatial orientation of covalent bonds to atoms having two or more bonding partners. Three dimensional configurations are best viewed with the aid of models. In order to represent such configurations on a two-dimensional surface (paper, blackboard or screen), we often use perspective drawings in which the direction of a bond is specified by the line connecting the bonded atoms. In most cases the focus of co
Topic : Working out oxidation states
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783
Engineering Entrance
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JEE Main
SOURCE:- Indian academy of science Working out oxidation states You don't work out oxidation states by counting the numbers of electrons transferred. It would take far too long. Instead you learn some simple rules, and do some very simple sums!· The oxidation state of an uncombined element is zero. That's obviously so, because it hasn't been either oxidised or reduced yet! This applies whatever the structure of the element - whether it is, for example, Xe or Cl2 or S8, or whether it has a giant structure like carbon or silicon.· T
Topic : Sub atomic particles
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684
Engineering Entrance
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JEE Main
Elementary particlesElementary particles are particles with no measurable internal structure; that is, they are not composed of other particles. They are the fundamental objects of quantum field theory. Elementary particles can be classified according to their spin, with fermions having half-integer spin and bosons integer spin.Standard ModelThe Standard Model of particle physics is the current understanding of the physics of elementary particles. All Standard Model particles except the Higgs boson have been observed.Fermions (half-integer spin) Quark structure proton: 2 up quarks and 1 down quark.Fermions have half-integer spin; for all known elementary fermi
Topic : Periodic trends
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643
Engineering Entrance
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JEE Main
Trends in the Periodic TableThe properties of the elements exhibit trends. These trends can be predicted using the periodic table and can be explained and understood by analyzing the electron configurations of the elements. Elements tend to gain or lose valence electrons to achieve stable octet formation. Stable octets are seen in the inert gases, or noble gases, of Group VII of the periodic table. In addition to this activity, there are two other important trends. First, electrons are added one at a time moving from left to right across a period. As this happens, the electrons of the outermost shell experience increasingly strong nuclear attraction, so the electron
Topic : nuclear chemistry-intro
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653
Engineering Entrance
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JEE Main
Nuclear Chemistry deals with the nuclei of atoms breaking apart. Atoms are continually undergoing decay. When studying nucle ar chemistry, there is a typical format used to represent specific isotopes.Nuclear equations are typically written in the format shown below. There are 5 different types of radioactive decay. Alpha decay follows the form: Where A is the parent isotope (the atom being broken apart) B is the daughter isotope or the isotope formed. When an element is broken down in alpha decay it looses two neutrons and two (2) protons. This means that the name of the element will change as well, moving back two (2) places on the per iodic table. Alpha
Topic : Organic- REVIEW SUMMARY OF ISOMERISM.....LOOK NO FURTHER
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935
Engineering Entrance
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JEE Main
General Summary of Isomerism and Molecular Descriptors Methods of Describing Molecules with Increasing Refinement CompositionThe number and kinds of atoms that make up a molecule. This information is supplied by a molecular formula. ConstitutionThe bonding pattern of the atoms of a molecule (ie. which atoms are connected to which other atoms and by what kind of bonds). Different bonding constitutions are interconverted only by breaking and reforming covalent bonds. This information is supplied by a structural formula, and is implic
Topic : short notes....bonding & molecular structure
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1522
Engineering Entrance
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JEE Main
BONDING AND MOLECULAR STRUCTUREChemical BondsThe attractive force which holds various constituents (atoms , ions etc) together in different chemical species is called chemical bond. The chemical bond can be classified into various types like ionic bond, covalent bond, coordinate bond, metallic bond, hydrogen bond and van der waal?s forcesCauses of chemical combinationThe tendency or urge of atoms of various elements to attain stable configuration of 8 electrons in the valency shell is the cause of chemical combination. The principle of attaining maximum of eight electrons in the valency shell of atoms is called octet rulesIt is expected that isolated atoms which hav
Topic : objective Q's.....atomic structure
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896
Engineering Entrance
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JEE Main
11. Canal rays are(a) fast moving electrons (b)slow moving neutrons ( c)deflected by electric field (d)deflected by magnetic field (e) both ( c) & (d)2. Bombardment of Beryllium by alpha particles by alpha particles led to the discovery of(a)electrons (b)protons ( c)neutrons (d)nucleus (e)positrons3. The most important defect of Rutherfords model of atom is that(a)it does not mention about the nucleus of atom(b)it does not mention about the equivalence of centrifugal force of revolving electron and the attractive e force of revolving electron( c)it does not obey the Maxwell law of electrodynamics(d)it does not explain the atomic spectra (e) both ( c)
Topic : short note...atomic structure
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623
Engineering Entrance
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JEE Main
ATOMIC STRUCTURE John Dalton in 1803 suggested that all matter is made up of small invisible particle is called atoms. However modern experimental evidences proved that an atom still contains small particles is called fundamental particles of atoms. The most important fundamental particles, electrons, protons and neutrons are present in atoms of all elements except hydrogen which contains only electron and proton Rutherford Model of Atom.Rutherford performed alpha particles scattering experiment and concluded that total mass and total positive charge of atom is concentrated in the small nucleus of radius 10-14- 10-15 m.Around this nucleus electrons rotate
Topic : CHIRAL CENTER CONFIGURATION-how to designate?
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1116
Engineering Entrance
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JEE Main
Designating the Configuration of Chiral CentersAlthough enantiomers may be identified by their characteristic specific rotations, the assignment of a unique configuration to each has not yet been discussed. We have referred to the mirror-image configurations of enantiomers as "right-handed" and "left-handed", but deciding which is which is not a trivial task. An early procedure assigned a D prefix to enantiomers chemically related to a right-handed reference compound and a L prefix to a similarly related left-handed group of enantiomers. Although this notation is still applied to carbohydrates and amino acids, it required chemical transformations
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