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Chapter 2 Matter and Change

Chapter 2 Matter and Change. Section 2.1 Matter. OBJECTIVES: Identify the characteristics of matter and substances. Section 2.1 Matter. OBJECTIVES: Differentiate among the three states of matter. Section 2.1 Matter. OBJECTIVES:

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Chapter 2 Matter and Change

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  1. Chapter 2Matter and Change

  2. Section 2.1Matter • OBJECTIVES: • Identify the characteristics of matter and substances.

  3. Section 2.1Matter • OBJECTIVES: • Differentiate among the three states of matter.

  4. Section 2.1Matter • OBJECTIVES: • Define physical property, and list several common physical properties of substances.

  5. What is Matter? • Matter is anything that takes up space and has mass. • Mass- amount of material or “stuff” in an object • Weight is due to gravity, and changes from location to location; mass is always constant.

  6. Types of Matter • Substance- a particular kind of matter - pure; is uniform (all the same) and has a definite composition (examples are elements & compounds) • water; gold; lemonade? • Mixture- more than one kind of matter; has a variable composition

  7. Properties • Words that describe matter (adjectives) • Physical Properties- a property that can be observed and measured without changing the composition. • Examples- color, hardness, m.p., b.p. • Chemical Properties- a property that can only be observed by changing the composition of the material.

  8. States of matter • Solid- matter that can not flow (definite shape) and has definite volume. • Liquid- definite volume but takes the shape of its container (flows). • Gas- a substance without definite volume or shape and can flow. • Vapor- a substance that is currently a gas, but normally is a liquid or solid at room temperature. (water vapor?)

  9. States of Matter Definite Volume? Definite Shape? Temp. increase Com-pressible? Small Expans. Solid YES YES NO Small Expans. Liquid NO NO YES Large Expans. Gas NO NO YES

  10. Condense Freeze Evaporate Melt Gas Liquid Solid

  11. Physical Changes • A change that changes appearances, without changing the composition. • Ex. Boil, melt, cut, bend, split, crack • Boiled water is still water. • Chemical changes - a change where a new form of matter is formed. • Ex. Rust, burn, decompose, ferment

  12. Section 2.2Mixtures • OBJECTIVES: • Categorize a sample of matter as a substance or a mixture.

  13. Section 2.2Mixtures • OBJECTIVES: • Distinguish between homogeneous and heterogeneous samples of matter.

  14. Mixtures • Physical blend of at least two substances; variable composition • Heterogeneous- mixture is not uniform in composition • Chocolate chip cookie, gravel, soil. • Homogeneous- same composition throughout; called “solutions” • Kool-aid, air, salt water • Every part keeps it’s own properties.

  15. Solutions • Homogeneous mixture • Mixed molecule by molecule • Can occur between any state of matter • Table 2.3, page 33 • gas in gas; liquid in gas; gas in liquid; solid in liquid; solid in solid (alloys), etc.

  16. Solutions • Like all mixtures, they keep the properties of the components. • Some can be separated easily by physical means: rocks and marbles, iron filings and sulfur • Other methods: distillation- takes advantage of different boiling points

  17. Section 2.3Elements and Compounds • OBJECTIVES: • Explain the differences between an element and a compound.

  18. Section 2.3Elements and Compounds • OBJECTIVES: • Identify the chemical symbols of common elements, and name common elements given their symbols.

  19. Substances • Elements- simplest kind of matter • cannot be broken down any simpler • all one kind of atom. • Compounds are substances that can be broken down only by chemical methods • When broken down, the pieces have completely different properties than the original compound. • Made of two or more atoms, chemically combined (not physical blend!)

  20. Made of one kind of material Made of more than one kind of material Made by a chemical change Made by a physical change Definite composition Variable composition Compound or Mixture Compound Mixture

  21. Element Compound Mixture Which is it?

  22. Chemical Symbols & Formulas • Currently, there are 115 elements • Each has a 1 or two letter symbol • First letter always capitalized; the second never; chemical “shorthand” • Don’t need to memorize all of them; know Table A.3 inside back cover • Some from Latin or other languages; note Table 2.4, page 40

  23. Section 2.4Chemical Reactions • OBJECTIVES: • Differentiate between physical and chemical changes in matter.

  24. Section 2.4Chemical Reactions • OBJECTIVES: • Apply the Law of Conservation of Mass.

  25. Chemical Reactions • When one or more substances are changed into new substances. • Reactants- stuff you start with • Products- What you make • ability to undergo chemical reaction is called a chemical property • products have NEW PROPERTIES • Arrow from reactants to products

  26. Indications of a chemical reaction: • Energy absorbed or released (temperature changes hotter or colder) • Color change • Gas production (bubbling, fizzing, or odor change) • formation of aprecipitate- a solid that separates from solution (won’t dissolve) • Irreversibility- not easily reversed

  27. Law of Conservation of Mass • Mass can not be created or destroyed in ordinary (not nuclear) chemical reactions or physical change • All the mass can be accounted for. • Burning of wood results in products that appear to have less mass as ash; where is the rest?

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