26 26 CHEMISTRY UNIT 2 STRUCTURE OF ATOM The rich diversity of chemical behaviour of different elements can be traced to the differences in the internal structure of atoms of these elements. After studying this unit you will be able to • know about the discovery of electron‚ proton and neutron and their characteristics; • describe Thomson‚ Rutherford and Bohr atomic models; • understand the important features of the quantum mechanical model of atom; • understand
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In the past benzene was obtained from the distillation of coal in the absence of air. Today most benzene is made syntheticallyfrom petroleum products. The benzene is a closed ring of six atoms connected by bonds that resonatebetween single and double bonds; each carbon is also bound to a single atom. Benzene isinsoluble in water but mixes in all proportions with organic . Benzene is itself an excellentsolvent for certain and for most simple organic chemicals. It is one of the most commonly
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Atom History Essay An Atom is a basic unit of matter that consists of a dense‚ central nucleus surrounded by a cloud of negatively charged electrons. The Atom was theorized by a man named Democritus of Abdera‚ Thrace in between c.a 460 BC - ca. 370 B.C. Atom is derived from the Greek word “atomos” ‚ which means to be uncuttable. He had a theory that everything is composed of “atoms”‚ which he believed that these minuscule objects are indivisible‚ indestructible and have and always been in motion
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CBSE TEST PAPER-01 CLASS - IX Science (Atoms and Molecules) 1. Atomic radius is measured in nanometers and (a) 1nm = 10-10m (b) 1m = 10-10nm (c) 1m = 10-9nm (d) 1nm = 10-9m 2. Symbol of Iron is :- (a) Ir (b) I 3. Atomicity of chlorine and Argon is (c) Fe [1] (d) None of these [1] [1] (a) Diatomic and Monoatomic (b) Monoatomic and Diatomic (c) Monoatomic and Monoatomic (d) Diatomic and Diatomic 4. Molecular mass of water ( H 2O ) is (a) 18g 5. State law of conservation of Mass
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Senior Science Half-Yearly Revision 1. Surface tension - A property of the surface of a liquid. It is what causes the surface portion of liquid to be attracted to another surface‚ such as that of another portion of liquid. Surface tension is caused by cohesion (the attraction of molecules to like molecules). Since the molecules on the surface of the liquid are not surrounded by like molecules on all sides‚ they are more attracted to their neighbours on the surface. Mercury has a high surface
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IGCSE London Examinations IGCSE Anthology for English Language (4355) For examination in May and November 2005‚ 2006‚ 2007 April 2003‚ Issue 1 delivered locally‚ recognised globally Anthology Anthology for English Language (4355) London Examinations IGCSE Edexcel is one of the leading examining and awarding bodies in the UK and throughout the world. We provide a wide range of qualifications including academic‚ vocational‚ occupational and specific programmes for employers. Through
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Introduction An atom is the smallest part of an element that can take part in a chemical change. The word “atom” comes from the Greek “atomos”‚ which means “unable to be cut”. Atomism is the philosophy of the existence of atoms. The first theories of atoms come from India. There was a Hindu sage named Kanad that hypothesized that all mater was composed of earth‚ water‚ light‚ wind‚ ether‚ time‚ space‚ mind and soul. Then another philosopher named Pakuda Katyayana suggested that everything can be
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communication will be assessed in your responses to Sections B and C – you should take particular care on these questions with your spelling‚ punctuation and grammar‚ as well as the clarity of expression. Copies of the Edexcel Anthology for IGCSE English Language and IGCSE English Literature may not be brought into the examination. Dictionaries may not be used in this examination. Advice Read each question carefully before you start to answer it. Keep an eye on the time. Try to answer every question
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IGCSE Accounting Teacher’s guide Edexcel IGCSE in Accounting (4AC0) First examination 2011 Edexcel‚ a Pearson company‚ is the UK’s largest awarding body‚ offering academic and vocational qualifications and testing to more than 25‚000 schools‚ colleges‚ employers and other places of learning in the UK and in over 100 countries worldwide. Qualifications include GCSE‚ IGCSE‚ AS and A Level‚ NVQ and our BTEC suite of vocational qualifications from entry level to BTEC Higher National Diplomas
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The History of the Atom The History of the Atom Democritus first proposed an atomic model. He said that all matter could be divided into smaller and smaller pieces until a single indivisible particle was reached. He called this particle an atom after the Greek word ‘atomos’ meaning not cuttable. He believed that different atoms are of different sizes‚ have regular geometric shapes and are always in motion. He also said that there is empty space between atoms. Aristotle severely criticized Democritus’
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