Lesson 3.01: History of the Periodic Table 1. Explain how scientific observations led to the development of‚ and changes to‚ the periodic table. Dmitri Mendeleev- first periodic table‚ organized 63 known elements according to properties‚ organized into rows and columns. He wrote names‚ mass and chemical properties on each. Julius lothar Meyer- independently worked in German ‚ similar to Mendeleev Henry Gwyn Jeffrey’s Moseley: worked with Ernest Rutherford experimented with 38 metals‚ he found that
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Promethium‚ Pm‚ is the 61st element on the Periodic Table. It was discovered in 1945 by Jacob A. Marinsky. It’s a metal‚ and named after the Greek God Prometheus. It is not naturally occurring‚ but can survive outside of a lab. Promethium has an atomic number of 61‚ which is the number of protons. Its atomic mass‚ protons+neutrons‚ is 145u. It is an isotope. This means that it has a different number of neutrons (84) than the number of electrons and protons (61). Every element changes states
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in the d-block and it is a transition metal. Technetium is in the 7th group in the periodic table because it has 1 electron on its last shell. Also it is in the 5th period in the periodic table because it has 5 shells. Number of energy levels of Technetium is 5. Its electron shells are 2‚8‚18‚14‚1 as it is in the picture. Firstly‚ Russian chemist Dmitri Mendeleev‚ who is the creator of the periodic table‚ predicted Technetium’s existence. He called it eka-manganese because there was a missing element
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The Development of the Periodic Table Although Dmitri Mendeleev is often considered the ‘father’ of the periodic table‚ the work of many scientists contributed to its present form. Between 1817-1829‚ Johann Dobereiner began to group elements with similar properties in to groups of three or triads. This began when he noticed that the atomic weights of strontium (Sr) were halfway between Calcium (Ca) and Barium (Ba). He stated that nature contained triads of elements in which the middle element
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How does chlorine effect the evaporation of pool water? Over time‚ sunlight and evaporation cause the chlorine and other chemicals in pool water to lose their effectiveness. Chemicals that are designed to disinfect swimming pools have chlorine concentrations ranging from approximately 12 to 95%. The concentration must be high because the chemicals are designed to be diluted in water. The amount of chlorine you need to add to a swimming pool is greater than the amount you need to add to regular drinking
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The Periodic Table By Eric Scerri 1. I just returned home from being interviewed for a new public television program on the mystery of matter and the search for the elements. It was very gratifying to see how keen the film-makers were on understanding precisely how Mendeleev arrived at his famous first periodic table of 1869. This in turn meant that I had to thoroughly review the literature on this particular historical episode‚ which will form the basis of this blog. 2. The usual version of how
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History of Table Tennis February 10‚ 2009 Table tennis‚ also known as ping pong‚ is a sport in which two or four players hit a lightweight‚ hollow ball back and forth with rackets (also known as ’bats’ or ’paddles’). The game takes place on a hard table divided by a net. Players must allow a ball played toward them only one bounce on their side of the table and must return it so that it bounces on the opposite side. Points are scored when a player fails to return the ball within the rules. Play
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Sodium‚ one of many elements in the periodic table is being used in everyday life‚ it is also an essential element within your body. It is just another element‚ but one of the differences is that this element is something that most people consume every day. Sodium has played an important role in everyday life because of its uses in medicine‚ industry‚ and agriculture(Shriver). Sodium was discovered in 1807 by a man named Sir Humphrey Davy. He was well known for his discoveries of most alkali metals
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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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Table Tennis Table Tennis The Table Tennis sport got its start near the end of the 19th century in England. After dinner one night‚ some Victorians decided to turn their dinning room table into a miniature version of lawn tennis. They lines up books as a net‚ used lids from empty cigar boxes as rackets‚ and the ball was made from string (table tennis balls were also made from champagne corks or rubber). Started as an after dinner activity‚ over the years‚ table tennis would turn into a sport
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