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Describing Matter

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  1. Chapter 1 Section 1 Describing Matter

  2. What is Matter? Matter is anything that has mass and takes up space.

  3. What is Chemistry Chemistry is the study of the properties of matter and how matter changes. A substance is a single kind of matter that is pure. Meaning, that it always has a specific makeup—or composition—and a specific set of properties. What is a substance?

  4. Properties/Characteristics of Matter • PHYSICAL • Luster (shine) • Hardness • Texture • Shape • Size • CHEMICAL • Flammability • Color • Temperature Examples of Physical Characteristics

  5. Properties of Matter • Physical Property • Example: A physical property of oxygen is that it is a gas at room temperature. • Chemical Property • Example: A chemical property of oxygen is that it reacts with iron to form rust. • Every form of matter has two kinds of properties: • physical • 2) chemical

  6. Changes in Matter: Physical vs. Chemical Change Examples in alterations: Physical Changes Altered in form but not identity. • Change in state (i.e., boiled water) • Separate parts of a substance (i.e., strained pulp from juice) • Appearance (i.e., crushed can)

  7. Characteristic Properties of Matter Characteristic properties of matter never change. • Characteristic properties hold true for a given substance and never change. • Since characteristic properties never change, they can be used to identify unknown matter.

  8. Physical Properties: Characteristic Properties • Solid • Liquid • Gas • Melting Point. The temperature at which a solid becomes a liquid. • Solids become liquids at different temperatures. • Ice melts at 0°C.

  9. Physical Properties: Characteristic Properties • Boiling Point. The temperature at which a liquid boils. • Different liquids boil at different temperatures. • Water boils at 100° C.

  10. Look at the melting points (MP) and boiling points (BP) of the five substances. Identify each substance’ s physical state at room temperature (°C). Is it solid, liquid, or gas? Explain your conclusion. SubstanceMPBP Water 0 100 Chloroform -64 61 Ethanol -117 79 Propane -190 -42 Salt 801 1465 Activity Room Temperature 20°C = 68°F. Take the °C. 1. Multiply by 1.8. 2. Add 32. The result is °F.

  11. Chemical Changes A chemicalchange occurs when one or more new substances is formed. • Made of same elements as original substances. • Elements are in different combinations than in original substances. • Elements may combine to make compounds. • Compounds may be broken down into elements. • Compounds may change into other compounds.

  12. Chemical Changes Chemical changes are the same as chemical reactions. Examples. Rusting – turns iron into iron oxide. Tarnishing – black residue on silver.

  13. Chemical Changes Burning – wood combines with oxygen to make carbon dioxide and water. Explosion.

  14. Stop Here.

  15. Types of Matter: Pure Substance vs. Mixture Matter is classified into two general categories. • Pure Substance • Element • Compound • Mixtures • (Combination of pure substances.) • Heterogeneous • Homogeneous

  16. Pure Substance: Elements Element. A pure substance that cannot be broken down into other substances by any physical or chemical means. • Only a few more than 100 elements exist. Elements that cannot be broken down into simpler substances. • You come in contact with only 30-40 elements in your daily life. • Examples: Carbon, Chlorine, Copper, Nitrogen • (Periodic Chart)

  17. Pure Substance: Compounds A compound may be represented by a chemical formula, which shows the elements in the compound and the ration of atoms. When elements are chemically combined, they form compounds having properties different from those of the uncombined elements. Chemical Formula Examples: NaCl (table salt): 1 Sodium (Na) 1 Chloride (Cl) CO2 (carbon dioxide) 1 Carbon (C) 2 Oxygens (O)

  18. Mixtures All matter is composed of one element or a combination of different elements. Mixtures differ from compounds in two ways: • Each substance in a mixture keeps its individual properties. • The parts of a mixture are not combined in a set ratio. • Example: Salt water.

  19. Mental How are pure substances related to mixtures? Use the graphic organizer “Concept Map” for matter.

  20. Addressing Misconceptions Question: How can a pure substance be a compound and still be ‘pure’?

  21. Addressing Misconceptions Answer: In a pure substance, whether element or compound, all the particles that make up the substance are the same, although each particle may be a combination of different particles. In a mixture, the particles that make up the substance will be different.

  22. Are you ?