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CHEMISTRY Unit 3 & Unit 4 Review Element An element is a pure substance made of only one kind of matter. The Periodic Table lists all the known elements Element Cube Each element on the Periodic Table gives information about the element Know how to find: Protons (5) Electrons (5) Atomic Mass (11) Neutrons (Atomic Mass-Protons = 6) Show me… Groups stay together Period! 1 1 Group 1 18 2 13 14 15 2 3 3 4 4 55 5 66 4 5 6 7 Period Rare Earth Rare Earth 6 7 7 88 9 1010 11 12 1 16 17 Mixture A substance of two or more elements mixed together. Substances are held together by physical forces, NOT chemical. Can be easily separated. MIXTURE OF CANDY TRAIL MIX SALAD SALT WATER SOLUTION Compound A substance made by chemically combining two or more elements. Can only be separated by chemical means NOT physical. Chemical and physical properties are different than the elements they are made from. Table Salt (NaCl) Water (H2O) Alkaseltzer (Sodium Bicarbonate – NaHCO3) Table Sugar (C12H22O11) Physical Properties A property that can be observed, measured or changed without changing the substance itself Examples of Physical Properties • • • • • • Odor Density Mass Volume State Color Chemical Properties A property of matter that describes a substance based on its ability to change into a new substance with different properties. Poisonous Gas + Explosive Powder = Table Salt Examples of ChemicalProperties • • Flammability Reactivity Physical Change A change that affects one or more physical properties of a substance Chemical Change A change that happens when two or more substances are changed into one or more new substances with different properties. Evidence of Chemical Reactions •Temperature Change •Heat is absorbed by the substances causing the temperature to decrease •Heat is released by the substances causing the temperature to increase Evidence of Chemical Reactions •Fizzing •When a gas is formed it may try to escape causing bubbles Evidence of Chemical Reactions Chemical Change •Color Change •This is evidence of a chemical reaction only when the other properties have also changed. Not a Chemical Change Evidence of Chemical Reactions •Precipitate Formed •Precipitate is a solid substance formed when liquids are combined Evidence of Chemical Reactions •Light •When a new substance is formed light energy can be produced. Know Chemistry Vocabulary #5 1. Oxidation - The combination of a substance with oxygen and will form rust or tarnish. 2. Substance - that of which a thing consists; physical matter or material 3. Chemistry – The scientific study of the structure, properties, and reactions of the chemical elements and the compounds they form. 4. Chemist - A scientist specializing Frying an egg Chemical Change Red paint + Yellow paint = Orange Physical change Effervescent tablets bubbling Chemical Change Melting butter Physical Change Bending a paper clip Physical Change Sanding wood Physical Change Copper tarnishing (notice green on 2nd coin) Chemical Change Baking a Cake Chemical Change Explosion! Chemical Change Mixture of apples & watermelon Physical Change Eating & Digesting Food Chemical Change Can being Crushed Physical Change