PERIODIC CLASSIFICATION OF ELEMENTS Introduction There are 115 elements that are known at present. Some elements have similar properties whereas some others have completely contrasting properties Scientists began to look for some pattern in the properties of these elements Dobereiner’s triads In 1817‚ Johann Wolfgang Dobereiner‚ a German chemist‚ classified elements into groups based on their properties. He kept all elements having similar properties in one group. Most of his groups had three
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Title:Extraction:Extraction with acid and alkaline Objective: 1. To recover benzoic acid and p-dichlorobenzene from its mixture using acid-alkaline extraction. 2. To determine the percentage recovery and melting point of benzoic acid and p-diclorobenzene. Apparatus:Separatory funnel(250mL)‚Buchner funnel‚beaker. Materials:Benzoic acid‚p-dichlorobenzene‚ether‚10% NaOH‚conc.HCl‚distilled water‚ anhydrous CaCl2. Introduction: Organic compounds in an aqueous mixture can be separated
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“Two American Families” The PBS Frontline documentary “Two American Families”‚ produced by Bill Moyers‚ follows two middle class families in Milwaukie‚ one black and one white‚ for over a decade as they struggle to achieve the “American Dream”. This documentary mirrors the struggle of so many American families who work hard and play by the rules‚ yet fall victim in a struggling economy to a series of policy decisions made. The hand of policy ineffectively steered the lives of the two families featured
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Facts of the periodic table While Dmitri Mendeleev is most often cited as the inventor of the modern periodic table‚ his table was just the first to gain scientific credibility‚ and not the first table that organized the elements according to periodic properties. There are 90 elements on the periodic table that occur in nature. All of the other elements are strictly man-made. Technetium was the first element to be made artificially. The International Union of Pure Applied Chemistry‚ IUPAC‚ revises
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Table comparing the two systems showing differences and why. Component | System 1 | System 2 | Comments | Case | Novatech Cougar ATX Case with 500W PSUHigh Quality Steel Construction‚ Up To 4 x 5.25" & Up To 5 x 3.5" Drive Bays‚ Supports ATX £26.98 | Coolermaster Storm Series Stryker Case - White - No PSUSteel Construction‚ Up to 9 5.25" Drives‚ Supports up to XL-ATX Motherboards and multiple GPUs Organised in SLI or Crossfire£144.00 | System 1 case is simple. It has built in power supply
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The Periodic Table is a chart which arranges the chemical elements in a useful‚ logical manner. Elements are listed in order of increasing atomic number‚ lined up so that elements which exhibit similar properties are arranged in the same row or column as each other. Elements are also arranged in different families and periods based on similar characteristics. Also the grouping of elements into into subcategories Metals‚ Nonmetals‚ and Metalloids. The Periodic Table is one of the most useful tools
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Trends in the Periodic Table * Generally‚ the atomic radius decreases across a period from left to right and increases down a given group. The atoms with the largest atomic radii are located in Group I and at the bottom of groups. Moving from left to right across a period‚ electrons are added one at a time to the outer energy shell. Electrons within a shell cannot shield each other from the attraction to protons. Since the number of protons is also increasing‚ the effective nuclear charge increases
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Ngee Ann Polytechnic 6 Month Internship International Supply Chain Management Periodic Report 1 Brenda Lim S10093748J [pic] BA 090R Appendix 1 NGEE ANN POLYTECHNIC SCHOOL OF BUSINESS AND ACCOUNTANCY DECLARATION FORM (This form is to be submitted together with all reports) |Programme: |ISCM | |Module:
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The Periodic Properties of Atoms The Periodic Table: In the 1870’s‚ the Russian chemist Mendeleev developed the periodic table‚ based upon the relationship between the atomic weights of the elements and their chemical properties. As one ascends from lightest to heaviest elements‚ there is a periodic recurrence of chemical properties. For example‚ the elements with atomic numbers 2‚ 10‚ 18‚ 36‚ 54‚ and 86 all are chemically inert (the noble gases)‚ while those with atomic numbers one greater 3‚ 11
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Quality time has become a password in two career families vs. a one career family. Many working parents try to set aside time in their hectic days to devote to their children. but what are the qualities of "quality time‚" and what differences does a a two career family have compared to a one career family? These along with some other questions remain unclear in today’s society. Most parents are working at a full time job (forty hours a week) five days a week. Therefore‚ when the parents arrive
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