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Density

Density. an object’s mass per unit volume units:. Dog Wind Atoms Soil DNA Clouds batteries. Saliva Helium Democracy Car exhaust Gasoline Paper Bacteria A cell Wisdom Heat. Toothpaste Electricity A star Juice Sound The ocean Fear Peanut butter. Directions.

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Density

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  1. Density • an object’s mass per unit volume • units:

  2. Dog • Wind • Atoms • Soil • DNA • Clouds • batteries • Saliva • Helium • Democracy • Car exhaust • Gasoline • Paper • Bacteria • A cell • Wisdom • Heat • Toothpaste • Electricity • A star • Juice • Sound • The ocean • Fear • Peanut butter

  3. Directions • Classify these words into TWO groups. • Give a name to each group. • Add one more example to each group. • Raise your hand when you are done.

  4. Matter and Changes

  5. matter: has volume (takes up space), and mass • can be solid, liquid or gas

  6. chemistry: the study of matter and changes to matter

  7. physicalchange: the chemical composition (makeup or parts) of the matter stays the same. • Ex: state changes (solid to liquid to gas), changing shape (ripping, squishing)

  8. chemicalchange: a compound’s chemical composition (makeup) is changed – it becomes a new substance • ex: burning, rusting, reacting

  9. Chemical or Physical Change? • burning paper • folding a piece of paper • the reaction of KI and Pb(NO3)2 • combustion of gasoline • hammering gold into a ring • cutting a diamond • acid rain “melting” a statue • a pile of old iron rusting • separating water into H and O by using electricity

  10. Which of the following is an example of a chemical change? A. Ice cracking B. Sugar dissolving C. Milk souring D. Lead melting

  11. Which of these describes a pollution-producing process that involves only a physical change? A. Coal with a high sulfur content is burned, producing gases that cause acid rain. B. Chlorofluorocarbons are released, changing ozone in the upper atmosphere into oxygen. C. Hot wastewater is discharged into a lake, lowering oxygen levels in the water. D. Nitrogen oxide emissions combine with water vapor, producing nitric acid.

  12. Which of the following processes is an example of a physical change associated with an oak tree? A. Decomposition of bark by bracket fungi. B. Starches and sugars being broken down during energy production. C. Water and carbon dioxide being converted to glucose. D. Evaporation of water from the surface of the leaves.

  13. Which of the following represents a physical property? a. Copper tarnishes to green when weathered. b. Oxygen is flammable when ignited. c. Iron rusts when exposed to oxygen. d. Ice melts if left at room temperature.

  14. Write down one unique example of a physical change you see at school.

  15. Write down one unique example of a chemical change you see in your neighborhood.

  16. Water

  17. H2O

  18. Ice

  19. Dihydrogen monoxide

  20. States of Matter Solid Liquid Gas low temperatures high temperatures slow particle movement fast particle movement TAKES SHAPE AND VOLUME OF CONTAINER! FIXED VOLUME NO FIXED SHAPE FIXED VOLUMEFIXED SHAPE

  21. Which state… • Fixed volume and shape • No fixed shape and no fixed volume • Fixed volume but no fixed shape • Takes the shape and size of its container • Takes the shape, but not the size of its container

  22. Which state… • Can be squeezed (compressed) into a smaller space? • Exists at a low temperature? • Has medium particle motion? • Has particles that just vibrate a little bit?

  23. States of Matter and Transitions(Phases) SOLID SUBLIMATION FREEZING DEPOSITION MELTING EVAPORATION LIQUID GAS CONDENSATION

  24. Why does temperature change the state of a sample of matter? • Kinetic Theory: all matter is made of particles that are always moving. • Temperature: a measurement of Kinetic Energy (oC, K) • 0 Kelvin: absolute zero: no particle movement • 200 K is twice the particle movement of 100 K • Kinetic energy can overcome bond forces

  25. Solid Liquid Gas low kinetic energy (KE) high kinetic energy (KE)

  26. Bond forces hold particles together. • Kinetic energy may be great enough to break bonds between particles (in a gas)

  27. What transition? • Ice turns into water • Water turns into steam • Water turns into ice • Water vapor (gas) turns into rain in clouds • Water boils and turns to steam • An ice cube looks like it’s making steam! • Cream and sugar turns into ice cream. • Snow turns into water vapor.

  28. Which state… • Has the lowest Kinetic Energy? • Has very strong bond forces? • Has the highest Kinetic Energy? • Has bonds that are broken most easily? • Has bond forces similar to its Kinetic Energy?

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