Transition state

A chemical reaction happend in a simultaneous process that is start of breaking of one bond and forming of another bond. This two process happens concurrently. Simply to say one bond is breaking and another bond is forming. With an advancement of this process there found an intermediate state where there have highest energy and form a structure of odd compound . This is not a real molecule. It's next step is the final product. Here leaving atom is adjunct to the central atom with paetial bond and new atom is also that.

Solar system atomic model

Rutherford's atomic model

 To define the atom and atomic structure Rutherford proposed a model of atom that can explain the structure of atom. Though, this model have a few drawbacks, but it was the first acceptable model of atom. Rutherford's atomic model is the modified result of a world re known experiment to know the behaviour of alpha particles that is known as Rutherford's alpha particle scattering experiment. Rutherford and Marsden done an experiment that shows a significant alpha particles scattering through atom. This experiment of alpha particle scattering gives most of the idea of atomic structure that leads to  a modern model of atom latter.

Rutherford's alpha particle scattering experiment

 Human thirst of innovation was started from the primitive time of human origin. A one discovery of science leads scientists to drive for new discovery. After the discovery of smaller constituents of atom, electron, proton and neutron, scientists are aggressive to know that how these three particles located with the atom and what is the rearrangement of these particles within atom. To discover this Rutherford and Marsden done an experiment that is known as Rutherford's alpha particle scattering experiment. Alpha particle scattering experiment enables them to get a few idea about the structure of atom and the locality of electron and proton. Next it enable to give a model of atom that is known as Rutherford's atomic model  in which major statements of the atomic model comes from alpha particles scattering experiment.

Alpha particles scattering experiment is done by passing of alpha particles through thin gold foil. The direction of the alpha particles pass through are found in different direction. Few particles did not deflected, few particles showed a large deflection and some showed little deflection. Very wonder they observed that a little amount of alpha particles did not pass through the goil foil and returned back.

 From the result of the alpha particles scattering there found some idea about atomic structure and probably the location of the particles within atom. Though, alpha particle is positively charged, the deflection of alpha particle indicates that something positively charged particles exist near, from where alpha particles started to deflecting. Among the three constituent particles of atom proton is positively charged, electron is negatively charged and neutron is charge neutral. Hence, among the particles it should be proton that is responsible of alpha particle deflection. The alpha particles passing way that is more near to protons location that shows more deflection. The alpha particles that moves directly toward the centre of the atom that returns back and do not pass through. This indicates that the centre of the atom is dense and rigid. This is called nucleus consist with proton, neutron and other particles. A large number of alpha particles pass through the gold foil without any deflection. That proves that the atom have a large volume of empty.

 This alpha particle scattering experiment provides a wide range of information to establish an atomic model, but not sufficient.

 To give a complete model of atom, Rutherford tries to make a relationship of planets orbiting surrounding the sun. Hence, to describes the atomic model Rutherford take into consideration of Johannes Kepler's model of solar system by
 considering the atom with the behaviour of sun and its planet.

 Simpled form of Rutherford's solar system atomic model

The atomic model of Rutherford says that the electron in an atom is moving surrounding the nucleus, just like how the planets are moving surrounding the sun by an elliptical path. The electrons are in negatively charged and the nucleus is positively charged. All of the mass of an atom is concentrated in nucleus. Comparing with the volume of whole atom the volume of nucleus is negligible. The whole atom is electrically neutral, because the number of electron surrounding the nucleus is equal to the number of proton in nucleus.

 Evidence of Rutherford's atomic model

Not only the alpha particle scattering experiment is a strongest evidence of accepting most of the parts of Rutherford's atomic model. In modern science there have a wide range of evidence in favour of most of the statements of Rutherford's atomic model to accept. Few statements are very Wonder found that these are significantly coping the the theory of relativity.


Rutherford's atomic model shows that the total mass of atom is concentrated into nucleus. But if we agree about the statement we have to agree that the mass of electron is negligible or zero. But electron also a particle. If other particles such as proton and neutron will contain mass, why electrons mass will be zero? Einstein's theory of relativity shows us that mass is relative with speed, space and position. Consider an analogy that you bind a substance with a rope and hold another side of the rope with your finger. Start to moving your hand in rotational pattern. The dense substance that is bonded with rope will started to rotate surrounding the point. Very wonder the rotating substance will gradually changes its position in space. With the increasing of speed of rotation it will tends to gradually moving to upward. That indicates something overcoming the attraction of earth on the substance. Besides of vector role, there acts another factors which is theory of relativity. Something that will move more speed its mass will be more less. If some matter or particles achieve speed.

 Limitation of Rutherford's solar system atomic model

 With the emergence of electrodynamic theorem, it proves that with the spending of time electron will release energy and will become closer to nucleus spirally and ultimately it will fall into nucleus. Wave mechanics also shows that electron have two nature. These are particle nature and wave nature. These two nature suggested that electron will not move by an elliptical path. On the other hand, according to Neils Bohr, the electron will jump to lower energy state to higher energy state and higher to lower energy state. Hence it will create spectrum by absorbing and emitting energy.

 If we put Rutherford's atomic model with Plank's quantum theory of radiation, there we will find complexity. Plank's quantum theory of radiation does not support  Rutherford's atomic model.

Fission

To occurring a chemical reaction there needs two things simultaneously. That is breaking down a bond and forming a new bond. To breaking down an existing bond requires energy. Breaking down of a bond occurs in two mechanism. 1. Homolytic fission 2. Hetero lytic fission Homolytic fission is also called Homolysis. In this case the bonding electron are equally distributed between two atom. Homolydis happens in breaking down of sigma bond. Two free radicals are forms in homolysis. These free radicals are electrically inactive. Each free radical contains a non pair electron. Heterolytic fission is also called Heterolysis. In this case after breaking down of the bond one atom pocess two electron or whole number of electron and another do not pocess any electron.

Electromeric effect

Electromeric effect is reffered as an effect that involve with the pi bond of the molecule and the polarity happens for the displacement of the pi electron by outside reagents. Electromeric effect is just like a mesomeric effect but only difference is that it is due to the effect of eletrophiles. When any electrophiles attact to the pi electron tgere happens a polarity in the bond. This effects is called Electromeric effect. Electromeric effect reffered as E. Electromeric effect is a temporary effect. Iy happens only for the effect of reagent. Just consider an example hat defines electromeric effect sufficiently. In ethylene there have carbon carbon double bond ehere one is sigma bond and another is pi bond. Ehen any electrophiles get closer to the ethylene it attact to the pi orbital of the bond. A displacement of pi electron happened and therefore create polarity.

A chemical reaction and its relation with energy of the system and orbital structure of the atom

In a system where different atoms are available for a successful reaction. But only then reaction is possible when two or more atoms will closer to each other. If ayoms places in different position, it is not possible to make a succrssful reaction. Getting aproaches of the atom to each other in the system decreases the energy ofthe energy of the total system. Distance between the atoms are decreased with the decreasing of the total energy of the system. Innert gases do not undrgo in chemical reaction because their all of the orbitals are filled completely. Half filled orbital can undergo in chemical reaction due to they tends to fill completely their orbital structure.

Electronegativity

Electronegativity is the characteristics of any atom that determines how strongly it will attract the electron cloud to itself. Its simply to say that a tendency of getting negative charge by attract the electron to itself. In a bond of two atom the more electronegative atom will attract the electron with stronger than other. Hence, it will be partially negatively charged. In HCl chlorine is more electronegative than hydrogen. Hence it attracts electron to itself. The electron cloud nearby chlorine is more dese than the electron cloud of nearby hydrogen. Hence, chlorine is partially negative charged and hydrogen is partially ppsotive charged. The phenomenon in HCl may defined as polarity.

Mesomeric effect

Mesomeric effect

 For happening a successful reaction there need a successful attack by reagent to the substrate. Reaction is nothing but a simple thing that one bond will break down and other new bond will form and finally as a resut with new products. To happen this an attack is important by reagent. In what region of substrate the reagent will do attack is a considerable subject.  Where reagent will attack to the substrate is depend on three factors. These are inductive effect, mesomeric effect and electromeric effect. All of three factors are involved in distribution of electron cloud in bond beteen the atoms. Though every effect is just same with the main function, yet these are different in unique parameter.

The difference of inductive effect from mesomeric effect is that in inductive effect the unequal distribution of electron cloud happens in sigma bond and in mesomeric effect the unequal distribution of electron cloud happens in pi bond.


omeric effect involve in the pi bond of the molecule. It involve in interaction between two pi electron or pi electron with lone pair electron. In conjugated double bond compound the mesomeric effect is noticeable. In this case the displacement and shifting of electron happened and form a resonance structure. Just like inductive effect the mesomeric effect transmited through one steps to another step. The group attract electron to itself is have +M effect and that have releasing tendency that have +-M effect

 Cause of mesomeric effect

 Mesomeric effect is the results of the difference of the electronegativity. Two ato

Inductive effect

Inductive effect

 For a chemical reaction there need two things to happen. One of them a good interaction between substrate and reagent. Substrate is these chemical reactants that have to be attracted by the reagent for a chemical reaction. The attacking reagent that contains positively charge attracts to the substrates into that region where the electron density is very high. As same as the attacking reagent with negatively charged will attack at the region of substrate where electron density is comparatively low. The electron density in a substrate are also influenced by some factors. These are inductive effect, mesmeric effect and electromeric effect.

To a clear understanding about the inductive effect for a chemical reaction, let us try to understand about the word induction. The induction somewhat means a visual effect of something on other things without any touch. It simply to say obtaining some characteristics from other. In the study of magnetism someone may be familiar with the term induction. How a magnet turns a non magnetic iron into magnetic properties without any touch, is termed as induction process.

Not only in physics and chemistry, but also in biological science there have a wide role of induction. Scientists have shown that by an induction process genetic information mat also be transform.

inductive effect involve in sigma bond and creates polarity due to different electronegativity of different atoms in a bond. In a single bond it may seems that electron cloud would equally distributed between two atoms that is not real. Rather, electron distributes unequally due to different electronegativity of two atoms. This unequal distribution of the electron cloud creates polarity. This unequal distribution of electron cloud  is the results of induction of atoms.  The definition of inductive effect may given by the achieving of polarity of one atom with influence of other atom. The more electronegative atoms attract electron cloud closer to itself and it shows slight negatively charged and other shows partial positive charge. In a carbon chlorine bond, chlorine is more electronegative than carbon atom. Hence chlorine shows partial negative charged. Inductive effect are in two types. The group of atom or molecule that shows attracting the electron to themselves are called -I effects group. Oppositely that shows to releasing of electron is called +I effect groups. Chlorine, Fluorine, Iodine, Nitrogen di-Oxide have -I effect. Methyl,Ethyl these have +I effect. In a molecule with chain, inductive effect transmitted one bond to next bond.

Meso Compound

Meso compound is such kinds of compound that have a plane of symmetry that devides the compound in two equal parts and each parts of the compound is the mirror image of each other. Meso compound have no activity in rotation of plane polarized light.

Enantiomer and Recimic mixture

Enantiomer is a pair of optically active isomers which are the mirror image of each other. Two isomers of Lactic acid that rotates plane polarized light left by one and right by another. Enantiomers are stable, isolable. They are differ one from another by arrangement in space. Enantiomers are identical properties in all parameter without in terms of rotation of plane polarized light. Enantiomers rotate plane polarized light to the same degree, but in different direction. One rotates to right and others to left. The equal mixture of enantiomers are called racemic mixture. Racemic mixture do not rotate plane polarized light. Because one isomers activity to totate plane polarized light declined by the activity of other isomer in mixture.

Tautomerism

Tautomerism is two isomer where each of the isomer forms from the other isomer by shifting the electrons and ions and they stays in an equlibrium. There found two types of tautomerism. Keto forms and Enol forms. These two forms of isomer is interconvertible. The shifting of electron and hydrogen happend in this case. The basic difference of Tautomerism from the resonance structure is that, Resonance structure there have no existance of unique different molecule. It is only involved in electrons movement from one position to another position. But in tautomerism electron shifts from one position to another position to forms different molecule. Not only that in tautomerism the ions also shifts. The examples of tautomerism are the two isomeric form of Acetone. Here two forms are found. These are Keto form and Enol form. In keto form there found a ketone functional group but in Enol form there found an aldehyde functional group.