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Unit 02 : Lesson 2. Physical and Chemical Properties . Recall: . Physical change: (reversible) composition does not change, just appearance Chemical change: (irreversible) composition changes into a new substance. . Physical Properties.
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Unit 02 : Lesson 2 Physical andChemicalProperties
Recall: • Physical change: (reversible) composition does not change, just appearance • Chemical change: (irreversible) composition changes into a new substance.
Physical Properties • Physical Properties: can be observed or measured without changing the composition of matter. Physical properties are used to observe and describe matter. • Include density, magnetism, color, luster, ductility, viscosity, malleability, and conductivity.
Characteristics of Physical Properties • Density: "heaviness" of objects with a constant volume. D = M / V • Magnetism:force of attraction or repulsion between various substances, especially those made of iron and certain other metals; ultimately it is due to the motion of electric charges.
Cont. physical properties • Color • Luster: the state or quality of shining by reflecting light; glitter, sparkle, sheen, or gloss • Ductility: ability of a metal to plastically deform without breaking or fracturing,
Cont. physical properties • Malleability:property of a metal describing the ease with which it can be hammered, forged, pressed, or rolled into thin sheets • Conductivity: a measure of a material's ability to conduct an electric current and heat
Cont. physical properties • Viscosity: the resistance for liquid to flow
Chemical Properties • Chemical properties: allow a substance to react forming new substances. • Include: corrosiveness, flammability, and oxidation.
Characteristics of chemical change • Corrosiveness: having the quality of corroding or eating away; erosive • Flammability: how easily something will burn or ignite, causing fire or combustion.
Cont. chemical properties • Oxidation: The combination of a substance with oxygen. A reaction in which the atoms in an element lose electrons and the valence of the element is correspondingly increased.
Materials can be classified as: (Each category has its own distinct properties). • Metals: shiny, ductile, malleable and good conductors of heat and electricity. • Nonmetals: generally poor conductors of heat and electricity. • Metalloids: have some chemical/physical properties of metals and some properties of nonmetals. • Si, Ge, As are semiconductors (conduct electricity slightly better than a nonmetal, but not as well as a metal.
Your Turn: • Give an example of a chemical change • Give an example of a physical change • Give a characteristic of a chemical property. • Give a characteristic of a physical property. • Who are great conductors? Metals or Nonmetals • Who have both characteristics of both metals and nonmetals?