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THE ATOMIC NUCLEUS INTRODUCTION: The beginning of twentieth century. not only witnessed the successful development of atomic hypothesis the old quantum theory of radiation by plank, and Einsteins special theory of relativity; these years also marked the beginning of nuclear physics as a new field of scientific activity. In 1886 Henri Bacqueral first observed the phenomena of radioactivity.A year after J.J Thomson discovered the electron.Later on Thomson demonstrated that cathode rays were constituted of electrons..In the way of notion of the atom as the ultimate indivisible unit of matter had to be discarded, and it become evident that atoms included electrons among their structure and these electrons could be liberated by electromagnetic excitation as in a gas discharge spontaneously as in radio activity. In 1902 Rutherford and Soddy showed that in radioactive decay an atom transform itself into a different chemical element.This discovery led to the development of models for nuclear s...

NUCLEAR RADIATIONS INTERACTION OF NUCLEAR RADIATIONS WITH MATTER In the previous article we have discussed natural radioactivity in which α and β particles and γ-rays are emitted from the disintegrating nucleus of an atom.In nuclear fission and fusion reactions neutrons and other particles together with certain radiations are emitted from the nucleus.Moreover, interaction of high energy particles (neutral or artificial) with matter produce certain nuclear or atomic reactions with emission of particles like protons,deutrons,neutrons and ionizing radiations like γ-rays from the nucleus and x-rays and ultraviolet rays from the atom.These particles and radiations have been studied carefully for their properties and effects with are as follows: ALPHA (α) PARTICLES It shoots out from the nucleus with a high velocity ( 0.1 × 10 ^ 8 m/s ). Thus it possesses very high energy 7.7 MeV for the most energetic from R ac.Due to its large size more charge and high energy it can make very l...

HEAT AS A FORM OF ENERGY IN TRANSIT Many scientist have tried to explain the nature of heat.Up to the beginning of the nineteenth century, it was considered a weightless fluid called caloric which existed in every material body.Hot bodies were said to contain more caloric than the cold bodies.The caloric theory could explain satisfactory many processes such as heat conduction and mixing of substance in calorimeter. This concept of heat fluid was challenged by Count Rumford.He observed while supervising the boring of cannon that as cannon barrels were being bored.A tremendous amount of heat was given off.According to the caloric theory since the metal chips cut off by the drill have lost caloric i.e the heat given off in the drilling process, the chips should not be the same as the original metal, which had not lost caloric.But Rumford was unable to find any difference between the chips and the original metal in respect to their ability to hold or give off heat.In order to further inves...

METALLURGY OF COPPER Copper occurs both in free as well as in combined states.In combined state,it occurs mainly as the sulphide and oxide ores.The chief ores of copper are copper pyrite or chaleopyrite (CuFeS2), chalocite (Cu2S) and malachite [Cu(OH)2] and azurite [2CuCO3 Cu(OH)2 blue. Extraction Copper is mostly extracted from sulphide ores which contain about 6% Cu.The sulphide ore is first roasted (i.e., heated strongly in a current of air) on the hearth of a large flat furnace whereby the following changes occur. (i) Large amount of sulphur burns to sulphur dioxide (SO2). (ii) Iron present oxidizes to ferrous oxide (FeO) (iii) Copper changes into cuprous sulphide (Cu2S) 2CuFeS2 + 4O2 -----------> Cu2S + 2FeO + 3SO2 The roasted material is then mixed with sand to remove iron as ferrous silicate a slag which floats on the surface of the molten matte of copper.The liquid copper matte containing cuprous sulphide with some unreacted ferrous sulphide (FeS) and silica oxidi...

GROUP TRENDS IN ALKALI AND ALKALINE EARTH METALS In this article,the group trends in properties such as electron negativity,ionization potential,heat of hydration,sizes of atoms and ions and other physical properties are discussed. (i) Electronegativity:- The elements have very small electronegativity values and very generally called electropositive elements.Electronegativity decreases from Li through Cs as one moves down the group.Pauling's electronegativity values IA ans IIA group elements are summarized. (ii) Ionization Potential:- s-Block elements in general have low first ionization enthalpies because the outer s-electron is shielded very effectively from the nucleus by the inner electrons.The first ionization enthalpy of each of the alkali metal is lower than corresponding alkaline earth element in the same period, because the latter has an extra nuclear proton which causes an increase in the electrostatic attractive force between the nucleus and the outermost electrons.Secon...

OPEN CHAIN AND CLOSED CHAIN HYDROCARBONS In aliphatic hydrocarbons, the carbon atoms are attached to another carbon to form chains.These chains may be either open or closed (rings) chains.The open chains on the basis of saturation of valence are classified as saturated and unsaturated hydrocarbons. (i) Saturated Hydrocarbons: The compounds in which all the valencies of carbon carbon atoms are fully satisfied by single bonds,are called saturated hydrocarbons.The examples of saturated hydrocarbons are alkanes. (ii) Unsaturated Hydrocarbons: The compounds in which all the valencies of carbon atoms are not fully utilized,are called unsaturated hydrocarbons.Alkanes and alkynes are the example of unsaturated open chain hydrocarbons. The hydrocarbons which contain closed chain of carbon atoms are called cyclic hydrocarbons and examples are cyclo alkanes and cyclo alkenes. Aromatic compounds are benzene and its homologs.These compounds are further divided into homonuclear and hetero-nuclear ar...