2. Chapter 2 The Human Organism and the Power of Energy

3. Lesson 2.1 Energy Types and Transformations

4. ENERGY ENERGY is the capacity to do work or cause a change There are many forms of energy Some forms of energy are listed on the next slide All forms of energy can be measured in JOULES The main unit of energy is the Joule (J). A Joule is the amount of energy it takes to lift a Newton (about 100g) one metre. 1000 Joules = 1 kilojoule (kJ)

5. Some Forms of Energy Energy FormEnergy source or example Solar EnergyEnergy from the sun or sunlight, eg. Solar panel Elastic EnergyEnergy from springs or elastics, eg. Watchsprings Electrical EnergyEnergy generated by electrical stations or batteries Wind EnergyEnergy from moving air, eg. Windmill Sound EnergyEnergy from sound, eg. Stereo speakers Hydraulic EnergyEnergy from moving water, eg. Waterfall or dam Thermal EnergyEnergy from hot, fast-moving molecules, eg. fire Radiant EnergyEnergy from electromagnetic radiation, eg. Light, heat Chemical EnergyEnergy from chemicals, eg. Food energy, Mechanical EnergyEnergy from moving objects, eg. Vehicles. These are the 4 energy forms that we will study in more detail.

6. THERMAL ENERGY Thermal energy comes from the random motion of the particles (molecules) that make up a substance. The faster the molecules of a substance move, the hotter the substance seems to us. ColdWarm Hot As you can see, even in solids, the molecules vibrate a bit Really fast molecules can even make flames!

7. Radiant Energy is contained in, and transported by electromagnetic waves Light is the most obvious form of radiant energy Other forms of radiant energy include: –X-Rays –Radio Waves –Ultraviolet Rays –Infra-red Radiation (radiated heat) –Gamma rays, cosmic rays (powerful radiation) RADIANT ENERGY

8. CHEMICAL ENERGY CHEMICAL ENERGY is stored in the bonds of molecule –Like the energy in gasoline, or wood that you burn, or any other form of fossil fuel. –Also, the energy used by life, such as the energy in food, is chemical energy.

9. MECHANICAL ENERGY MECHANICAL ENERGY results from the speed and mass of an object, and from its relationship to its surroundings. In other words, mechanical energy comes from the movement of objects. Falling objects, moving vehicles, mechanical devices and spinning wheels all have mechanical energy.

10. ENERGY TRANSFORMATION ENERGY TRANSFORMATION is changing energy from one form to another Examples: Radiant  to  Thermal (sun warms ground) Chemical  Radiant  Thermal (burning causes light & heat) Radiant  to  Chemical (photosynthesis) Log (chemical energy) Flame (radiant energy) Heat (thermal energy) Radiant (light) Thermal (heat) Radiant Food (chemical)

11. Assignments on Energy Types and Transformations Textbook pp. Workbook pp.23 to 26

12. Lesson 2.2 How energy causes changes in matter

13. Changes and Energy Energy can cause changes in matter, and changes in matter can produce energy.

14. Types of Changes: Two Types of Changes Physical Change Chemical Change

15. Physical Change: *there are a few physical changes that are difficult to reverse. Does not change the chemical composition of a substance. It does not affect the nature or characteristic properties of the substance. Process is usually* reversible –Ex.Crumpling & smoothing out paper –Ex.Freezing water and thawing ice –Ex.Sublimation – from solid to gas (ex. dry ice (CO 2 ) or iodine)

16. Physical Change Key Words: –C–Crush/Pulverize  Physical change –M–Melt  Physical change –E–Evaporation  Physical change Condensation  Physical change Sublimation  Physical change –S–Solidification  Physical change –D–Dissolve  Physical change Tells you a physical change occurred

17. Energy and Change of State (some people say “Phase” instead of “State”) Adding thermal energy to an object makes its particles (ie. Molecules) move faster. If the particles move fast enough, the substance may change state, going from solid to liquid or from liquid to gas. Change of state is a PHYSICAL change caused by changing the amount of thermal energy in a substance

18. Physical Changes of State LIQUID FUSION (Melting) SOLIDIFICATION(Freezing) VAPORIZATION (evaporation) CONDENSATION (liquid) DEPOSITION (solid sublimation) SUBLIMATION (gaseous) SOLID GAS When a substance changes state it is always a physical change! Its molecules don’t change They just move faster (or slower) Absorbs Energy Releases Energy

19. Chemical Changes: Changes the chemical composition or make-up of the substance New substances are formed with new properties Not easily reversible (Reversible only through chemical means or reactions) Rust

20. Signs of Chemical Changes: Tells you a chemical change occurred Formation of a gas when two substances mix. Formation of a precipitate from mixing two solutions. A significant change in color when materials react. Release of heat &/or light when materials are mixed Increase or decrease in mass

21. Be Careful! Pay attention to the “when” part of each clue. –Eg. “It is a chemical reaction if gas is released when two materials mix” –One of these is definitely a chemical change, the others are not: 1) Gas bubbles are released when a pop bottle is opened 2) Gas bubbles are released when vinegar and baking soda mix. 3) Gas bubbles are released when water boils. #2 is the chemical change. #1 is not, since the release of gas is due to pressure change. #3 is not, since it is a change of state (liquid to gas)

22. Pay attention to the “when” part of each clue. –“It is a chemical reaction if a significant change in colour occurs when materials react.” –One of these is definitely a chemical change, the others may not be: 1) Base added to phenolphthalein changes it from clear to bright purple-pink. 2) Wet blue jeans look darker than dry ones. 3) Mixing yellow and blue paint makes green paint. Be Careful! #1 is the chemical change. #2 is not, since the colour change is not significant. #3 is not, since it is a simple blending of existing colours, not a reaction.

23. Chemical Change: Synthesis The formation of a complex molecule out of atoms or simpler molecules. O O H H H H O 2 + 2 H 2 Three simple molecules 2 H 2 O Two more complex molecules O O H H H H become Synthesis

24. Al O O O O When complex molecules are transformed into simpler molecules or atoms O O Chemical Change: Decomposition Al O O O O O O 2 Al 2 O 3 two complex molecules 4 Al + 3 O 2 Seven simpler molecules or atoms Become...

25. Chemical Change: Oxidation When oxygen combines with a material to change it. rusting of iron or corrosion of any metal is an example of slow oxidation. Combustion or burning is an example of rapid oxidation. Fuel 4 Fe + 3O 2  2Fe 2 O 3 C + O 2  CO 2 Note: This type of oxidation is also a synthesis. Some oxidations may be decomposition.

26. Chemical Change: Precipitation In chemistry, precipitation is the formation of a solid that is insoluble following the mixing of two solutions In other words, if you mix two transparent solutions and produce a cloudy mixture that eventually settles to form a powdery solid, that is a chemical precipitation. Don’t mix up chemical precipitation with meteorological precipitation, which is rain or snow. Transparent Cloudy

27. Physical Change -Sublimation -Freezing -Condensation -Evaporation -Pulverization (crush) -Solidification -Dissolving Chemical Change - Burning - Neutralization - Combustion - Oxidation - Synthesis - Decomposition - Precipitation

28. Which of the following are examples of physical changes? 1.Melting Butter 2.Rusted Car 3.Dissolving Sugar in Tea 4.Crushing Rock 6.Burning Wood 5.Condensation

29. Which of the following are examples of chemical changes? 1.Cooking an egg 3.Sublimation of Dry Ice 2.Rotting food 4.Freezing Rain 6.Crumpling Paper 5.Burning a candle

30. You carry out the following steps of an experiment & record your observations. 1.You place a powder in a test tube 2.You heat the test tube. You notice that a colorless gas & a copper-colored liquid are produced. 3.You collect the copper-colored liquid & cool it. It becomes a solid. Where did a chemical change occur? A physical change?

31. Assignments on Physical and Chemical Changes Read Textbook pp. 43 to 58 Do Workbook pp. 23-26 (energy) Do Workbook pp. 27-36 (changes)

32. Chapter End Questions Textbook pages 59 to 61 Write down the date of the chapter 2 test in your agenda or homework book.