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Atomic system and Periodic Table Elements An element is a primaeval cognitive content that apprisenot be broken down by chemic means to simplier substances. An element consists entirely of atoms. E.g. H, He, O i.e. every the elements in the Periodic Table. Compounds A compound is a substance cool of elements combined in a fixed proportions. Compounds bay window further be broken down into simple units by chemical substance means. E.g. 2 water supply (l) ? 2H2(g) + O2(g) Mixtures A mixture is a combination of 2 or more substances in which the substances retain their identity. A mixture can be separated by physical means. E.g. Air ? H2(l) + O2(l) Symbols of the elements H, He, Li, Be, B, C , N, O, F, Ne, etc.. disposed that we have different elements and that they have different properties and characteristics, e.g. He, S, Fe, what is the amount-go of the difference mingled with onw element with an another? Atomic Theory of Matter all matter consists of minute, undividable particles called atoms which combine unitedly in various(a) ways. E.g. piddle, O2, CaCO3 Daltons Atomic Theory 1. Matter is quiet of undividable particles called atoms. 2. Atoms of the kindred element have the homogeneous physical and chemical properties. 3. Atoms of different elements have different weights ( smokestackes) 4. Chemical compounds are composed of 2 or more different atoms joined in concert in simple, fixed ratios.

The Law of Conservation of Mass In a chemical change, mass is conserved ( fundamental mass of reactants! = Total mass of products) E.g FeS ? Fe + S 87.8g 55.8 32g reactant (87.8g products) The Law of continual Composition The same compound, no matter how it is prepared, always contains the same elements combined in the same fixed proportion by mass. E.g.2H2 + O2 ? 2H2O % H in H2O = 11.2 % O in H2O = 88.8 Chemical Formulas...If you want to get a full essay, regularise it on our website: OrderCustomPaper.com

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