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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It is 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
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Periodic Table Trends Quiz 1. The most reactive metals are located in the lower left hand corner of the periodic table 2. Which of the following atoms listed below has the largest atomic radius? Ca 3. Compared to the atomic radius of a rubidium atom‚ the atomic radius of a strontium atom is smaller. The smaller radius is primarily the result of the strontium atom having greater effective nuclear charge 4. An element is most likely to have properties similar to those of another
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Joy Jenkins Changing of the periodic table Today‚ the periodic table organizes the elements in horizontal rows‚ or periods‚ by order of increasing atomic number. The elements are also organized in vertical columns‚ or groups‚ based on similar physical characteristics and chemical behavior. I believe the periodic table will continue to evolve as new elements are discovered. One of the earliest attempts to organize the elements based on their chemical and physical properties was made by German
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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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1 18 IUPAC Periodic Table of the Elements 1 H 2 He helium hydrogen [1.007; 1.009] 2 3 4 Li beryllium 9.012 11 14 15 16 17 4.003 5 atomic number Be lithium [6.938; 6.997] 13 Key: 6 7 8 9 10 O F Ne boron carbon nitrogen oxygen fluorine neon [10.80; 10.83] B [12.00; 12.02] [14.00; 14.01] [15.99; 16.00] 19.00 20.18 12 13 14 15 16 17 18 Na
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HISTORY OF THE PERIODIC TABLE How did the periodic table develop? Since a very long time‚ elements such as gold‚ silver‚ tin‚ copper‚ lead and mercury have been known. But the concept of elements have largely be changed since then. Many scientists did research and new scientific discoveries were found. The progress of science never ends. Lavoisier In 1789‚ French chemist Antoine Laurent Lavoisier discovered that an element is a fundamental substance that could not be broken down by
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Development of the periodic table ➢ The elements in the periodic table have been arranged in the order of the number of protons (a.k.a. atomic number) The next significant stage in the development of the periodic table was discovered by came from John Newlands. He arranged the known elements in order of their atomic masses. He introduced the ‘law of octaves’ which meant that every eighth element had similar properties. As it didn’t work for all the known elements it was therefore dismissed
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ON-THE-PAGE FACTORS These elements are in the direct control of the publisher THE PERIODIC TABLE OF SEO SUCCESS FACTORS Search engine optimization — SEO — seems like alchemy to the uninitiated. But there’s a science to it. Below are some important "ranking factors" and best practices that can lead to success with both search engines and searchers. OFF-THE-PAGE FACTORS Elements influenced by readers‚ visitors & other publishers CONTENT LINKS Cq Cr Cw Ce Cf Vt Va HTML QUALITY
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Subject: Chemistry Topic: The Periodic Table The periodic table is a classification of all the elements based on ATOMIC NUMBER. It is composed of HORIZONTAL PERIODS and VERTICAL GROUPS which contain the elements arranged: *the order of INCREASING ATOMIC NUMBER *in the relation to the ELECTRON STRUCTURE of the atoms *in the relation to their CHEMICAL PROPERTIES (Criteria Used For Placing ELEMENTS in the Periodic Table) 1. ATOMIC NUMBER 2. NUMBER OF SHELLS (PERIOD) 3. NUMBER OF OUTER
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