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					 			      	Periodic Table - Chart Of All Chemical Elements
					 			      	 
 The interactive periodic table of elements - chemical data, health and environmental effects presented in five languages. http://www.lenntech.com/periodic/periodic-chart.htm
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					 			      	Periodic Table of the Elements - Chemistry - Britannica
					 			      	 
 In chemistry, the organized array of all the chemical elements in order of increasing atomic number-i.e., the total number of protons in the atomic nucleus. http://www.britannica.com/science/periodic-table-of-the-elements
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					 			      	The Classification of the Chemical Elements - Scientific American
					 			      	 
 Everything in its beginning proceeds from the incomplete to the complete. This procedure we call progress, for progress is measured by the increase in value, spiritual or material. http://www.scientificamerican.com/article/the-classification-of-the-chemical/
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					 			      	How Are Elements Grouped? - Classification of Elements
					 			      	 
 Elements are classified into two main groups: metals and nonmetals. There are several subsets of metals, based on similar characteristics and chemical properties. http://www.livescience.com/28507-element-groups.html
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					 			      	Periodic Table of Elements: Los Alamos National Laboratory
					 			      	 
 Elements can generally be described as either metals or nonmetals. Metal elements are usually good conductors of both electricity and heat. http://periodic.lanl.gov/metal.shtml
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					 			      	The Elements Revealed: An Interactive Periodic Table - Scientific American
					 			      	 
 Whether gas, liquid or solid; radioactive or stable; reactive or inert; toxic or in your vitamin pill, the 118 building blocks each has its own chemically idiosyncratic characteristics--and certain commonalities. http://www.scientificamerican.com/article/chemistry-the-elements-revealed-interactive-periodic-table/
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					 			      	Development of the Periodic Table - Science Learn Hub
					 			      	 
 At present, 116 elements have been discovered - the first scientific discovery of an element occurred in 1649. http://sciencelearn.org.nz/Contexts/Just-Elemental/Looking-Closer/Development-of-the-periodic-table
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					 			      	Periodic Table - Wikipedia
					 			      	 
 The periodic table is a tabular arrangement of the chemical elements, ordered by their atomic number (number of protons in the nucleus), electron configurations, and recurring chemical properties. https://en.wikipedia.org/wiki/Periodic_table
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					 			      	Dynamic Periodic Table
					 			      	 
 Interactive periodic table with dynamic layouts showing names, electrons, oxidation, trend visualization, orbitals, isotopes, and compound search. Full descriptions from write-up sources. http://www.ptable.com
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					 			      	Periodic Table of Elements: Los Alamos National Laboratory
					 			      	 
 The Chemistry Division's Periodic Table describes the history, properties, resources, uses, isotopes, forms, costs, and other information for each element. http://periodic.lanl.gov/index.shtml