Elements and Compounds - Al Barium Ba Calcium Ca Chlorine...

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Elements and Compounds Pure substances have an invariable composition and are composed of either elements or compounds . Elements "Substances which cannot be decomposed into simpler substances by chemical means". Compounds Can be decomposed into two or more elements. Elements Elements are the basic substances out of which all matter is composed. Everything in the world is made up from only 109 different elements. 90% of the human body is composed of only three elements: Oxygen, Carbon and Hydrogen
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Elements are known by common names as well as by their abbreviations . These consisting of one or two letters, with the first one capitalized. These abbreviations are derived from English or foreign words (e.g. Latin, German). Element Abbreviation Carbon C Fluorine F Hydrogen H Iodine I Nitrogen N Oxygen O Phosphorus P Sulfur S Aluminum
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Unformatted text preview: Al Barium Ba Calcium Ca Chlorine Cl Helium He Magnesium Mg Platinum Pt Silicon Si Copper Cu (from cuprum ) Iron Fe (from ferrum ) Lead Pb (from plumbum ) Mercury Hg (from hydrargyrum ) Potassium K (from kalium ) Silver Ag (from argentum ) Sodium Na (from natrium ) Tin Sn (from stannum ) Compounds Compounds are substances of two or more elements united chemically in definite proportions by mass . For example, pure water is composed of the elements hydrogen (H) and oxygen (O) at the defined ratio of 11 % hydrogen and 89 % oxygen by mass . The observation that the elemental composition of a pure compound is always the same is known as the law of constant composition (or the law of definite proportions ). It is credited to the French chemist Joseph Louis Proust...
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