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Chapter 2 Matter and Change Chemistry pg. 38
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2.1 Properties of Matter Properties used to describe matter are classified as: 1. Extensive – depends on the amount of matter in a sample ex. Mass, volume 2. Intensive – depends on the type of matter in a sample, not the amount ex. Color, hardness, boiling point
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Substance Matter that has a uniform and definite composition ex. Gold, copper (pure substances) Every sample has identical intensive properties because every sample has the same composition
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Physical Property A quality or condition of a substance that can be observed or measured without changing the substance’s composition Help chemists identify substances Hardness Color Conductivity Malleability (see Table 2.1, Pg. 40)
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Three states of matter Solid-definite shape, volume, not easily compressed Liquid-indefinite shape, flows, definite volume, almost incompressible Gas-indefinite shape, indefinite volume, easily compressed http://www.chem.purdue.edu/gchelp/liquids/ character.html http://www.chem.purdue.edu/gchelp/liquids/ character.html
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Physical Changes Properties of a material change but the composition does not ex. Boil, freeze, melt, condense AND break, split, grind, cut, crush Physical changes can be REVERSIBLE or IRREVERSIBLE
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2.2 Mixtures Physical blend of 2 or more components ex. Chicken noodle soup, air Mixtures can be classified as… HETEROGENOUS or HOMOGENOUS (based on distribution of components)
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Matter can be Heterogeneous The composition is not uniform throughout More than one phase…so it’s a mixture -Phase – any region with a uniform set of properties that can be separated from each other by definite boundaries called interfaces
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Matter can be Homogeneous The composition is uniform throughout, evenly distributed Only one phase
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Identify the following Concrete __________________________ Vinegar____________________________ Carbon dioxide_____________________ Granite rock________________________ Milk________________________________
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Separating mixtures Distillation - a liquid is boiled to produce a vapor which is condensed into a liquid Other ways? distillation How to perform simple distillation in the chemistry lab | Wonder How To How to perform simple distillation in the chemistry lab | Wonder How To
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2.3 Elements and Compounds Substances classified as 1. __________- simplest form of matter that has a unique set of properties (O, H) 2. ___________- substance that contains 2 or more elements chemically combined in a fixed proportion (C 6 H 12 O 6 )
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Compounds can be broken down by ______________ means. Elements cannot be broken down Chemical change produces matter with a different composition than the original matter Sugar Carbon + Water
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Properties of Compounds Generally, properties of compounds are different from their component elements Sodium - soft, gray metal, reacts with oxygen + Chlorine - yellow-green poisonous gas Sodium chloride Reaction
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Distinguishing Substances and Mixtures If the composition of a material is fixed, the material is a substance examples? If the composition of a material may vary, the material is a mixture examples?
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Classifying Matter
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Classify the following materials as an element, compound, or mixture. a. Table salt b. Salt water c. Sodium
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Symbols and Formulas Chemical symbols elements O, C, Na, Ne Chemical formulas compounds CO 2, H 2 O
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2.4 Chemical Reactions Chemical Property – the ability of a substance to undergo a specific chemical change (describes the way a substance may react to form other substances) examples? - can be observed only when a substance undergoes a chemical change
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Fig. 2.13 (pg. 53) Chemical reaction S + Fe *physical - composition of matter never changes *chemical – composition of matter always changes Chemical change = chemical reaction Reactants Products
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Chemical change = chemical reaction (one or more substances change into one or more new substances) Reactants Products
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Recognizing Chemical Changes 4 Ways: 1. 2. 3. 4.
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Precipitate an insoluble substance that forms in, and separates from, a solution
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Identify clues for chemical changes magnesium ribbon in flame Sodium iodide solution added to mercury(II) chloride solution
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Law of Conservation of Mass In any physical change or chemical reaction, mass is ________________. mass of products = mass of reactants
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