Development of the Periodic Table It was in 1817 when Johann Wolfgang Döbereiner showed that the atomic weight of strontium lies midway between those of calcium and barium. Some years later he showed that other such “triads” exist (chlorine‚ bromine‚ and iodine and lithium‚ sodium‚ and potassium). Another way of classifying the elements was later proposed by John Alexander Reina Newlands in 1864. He proposed that elements be classified in the order of increasing atomic weights.
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atomic number and atomic mass. The Periodic Table organizes elements by their atomic number - from hydrogen (1) to whatever is the highest one currently known (>105). It is arranged so that similiar members fall in a list such as Chlorine Bromine etc.. The average atomic weight is usually shown with each element‚ but due to isotopes (caused buy nuclear varations) the weight is the normal average atomic weight. The table illustrates the similiarity of various elements such as metals‚ noble
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GLOBAL WARMING What Is Global Warming? Global warming is the warming of the earth through carbon dioxide (CO2) being pumped into the atmosphere from tailpipes and smokestacks. Then the gases trap heat like the glass in a greenhouse. This is where the term the “greenhouse effect” came from. What’s Happening Scientists say that the barrier insulating the continental ice caps is melting. “The impacts of warming temperatures in Antarctica
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located. During the years that it takes to reach the Ozone layer‚ the wind carries them all over the world which is a cause of depletion throughout the entire Ozone layer. When in the presence of Ultra Violet light‚ these gases release Chlorine/Bromine atoms which destroy some of the Ozone layer. This is called‚ depletion. A major effect of the Ozone layer depletion is harmful Ultra Violet rays being emitted into meters depth water‚ our soil‚ and all living beings. These Ultra Violet-B rays
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UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONS General Certificate of Education Advanced Subsidiary Level and Advanced Level CHEMISTRY Paper 1 Multiple Choice Additional Materials: Multiple Choice Answer Sheet Soft clean eraser Soft pencil (type B or HB is recommended) Data Booklet 9701/13 May/June 2010 1 hour *2288633369* READ THESE INSTRUCTIONS FIRST Write in soft pencil. Do not use staples‚ paper clips‚ highlighters‚ glue or correction fluid. Write your name‚ Centre number and
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The higher alkenes‚ like the alkanes‚ are liquids. However‚ they are different chemically. ================================ Reactions of Alkanes Important alkane reactions: Burns in air to form carbon dioxide and water Reacts with chlorine‚ bromine‚ and iodine only when the mixtures are exposed to UV light. ================================ Reactions of Alkenes Presence of double bond make alkenes very reactive. There are many substances which react with alkenes by opening out the double bond
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People may be surprised to know that makeup has its own past. In fact there is a long history of makeup that has led it to the point where it is today. Pharaohs and great queens of Egypt wore‚ makeup thousands of years ago and while it wasn’t composed of the same materials‚ they still used it in similar ways as people do today. Women and men have been wearing cosmetics for over centuries and still are now in days. The styles have certainly undergone some dramatic changes over time but makeup is still
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29) The structural formulas are given for these cis or trans alkenes. (a) trans-1‚2-dichloropropane (b) cis-2-pentene (c) cis-3-hexene (d) trans-2-hexene Write the structural formula for: (a) cis-1‚2-dichloropropene (b) trans-2-pentene (c) trans-3-hexene (d) cis-2-hexene 30) In each case‚ tell whether cis and trans exist. If they do‚ write the structural formulas for two isomers and label each cis or trans‚ (a) Br2CH2 : No (b) CH3CH2CH=CHCH2CH3: Yes (c) CH3CH=CHCH3:
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Abstract: The purpose of this lab was to synthesize triphenylmethanol from benzophenone and bromobenzene by the formation of a Grignard compound with the reagents bromobenzene and magnesium metal. The bromobenzene was first transformed into the Grignard compound and was then reacted with the benzophenone to make the final product. The mixture was then mixed with sulfuric acid and the organic layer was extracted via a separatory funnel. The mixture was then recrystallized from methanol and was allowed
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**List the more common ecological consequences to pollution in our oceans **Define sustainable yield **Define Exclusive Economic Zone **List the benefits and drawbacks of aquaculture **Define and explain the causes of eutrophication‚ red tides **List the main causes of ocean pollution **Define by-catch **Define precautionary principle **List the major consequences of global climate change on our ocean ecosystems **List the main ways we use global sea catch Ted talks: How I
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