1. Physical Science Review Pearl Junior High School 8 th grade Science

2. Obj. 2a - Conservation of Mass  Matter cannot be created nor destroyed  Therefore: The number of atoms must be equal on both sides of the equation the mass of the reactants must equal the mass of the products

3. Obj. 2a - Balancing Equations  What coefficient is needed below in order to satisfy the law of conservation of mass? (Hint: balance the equation!) CH 4 + __ O 2  CO 2 + 2H 2 O

4. Obj. 2a - Balancing Equations  How many molecules of Fe 2 O 3 (iron oxide - rust) will be produced if 3000 O 2 molecules react in the balanced equation below? 4Fe + 3O 2  2Fe 2 O 3

5. Obj. 2a - Balancing Equations  If 15g of Zn reacted with 25g of HCl to produce 20g of ZnCl 2, how much mass of H 2 would be produced? Zn + 2HCl  ZnCl 2 + H 2 15g 25g 20g ?

6. Obj. 2a - Photosynthesis and Respiration Photosynthesis carbon dioxide + water (sunlight)oxygen + glucose 6 CO 2 + 6H 2 O  6O 2 + C 6 H 12 0 6 Respiration Sugar + oxygen carbon dioxide + water + energy C 6 H 12 0 6 + 6O 2  6CO 2 + 6 H 2 O + energy

7. Obj. 2a - Chemical Equations (common compounds )  NaCl - table salt  H 2 0 - water  C 6 H 12 O 6 – sugar (glucose)  O 2 – oxygen gas  CO 2 – carbon dioxide  N 2 – nitrogen gas

8. Obj. 2b - Periodic Table Properties of Metals and nonmetals  Metals: on the left side of the periodic table in groups Malleable Ductile Good conductors of heat and electricity  Nonmetals: on the right side of the periodic table in groups Brittle Poor conductors of heat and electricity

9. Obj. 2b - Important Groups  Group 1 Alkali metals (most reactive metals)  Group 2 Alkaline Earth metals  Group 3-12 Transition Metals  Group 17 Halogens (most reactive nonmetals)  Group 18 Noble gases (completely non-reactive - 8 valence electrons)  Metalloids Touch the “zigzag” line; have some properties of metals & some properties of nonmetals

10. Where are the metals and nonmetals?

11. Groups  Vertical columns  Have similar properties  Group Number = number of valence electrons  Metals are more reactive as you move DOWN a group  Nonmetals are more reactve as you move UP a group

12. Obj. 2b - Types of Bonds  Atoms bond in order to become more stable!!  Ionic:  between a metal & non-metal  metal gives electrons to nonmetal so that they each have 8  Ex: NaCl (Group 1 metal gives its valence electron to Group 17 nonmetal)  Covalent:  between two or more non-metals  The nonmetals share valence electrons so that they each have 8  Ex: H 2 O (One oxygen atom shares a valence electron with each of two hydrogen atoms)

13. Obj. 2b - Periodic Table  Oxidation: when a substance reacts with oxygen Rusting (slow oxidation) 4Fe + 3O 2  2Fe 2 O 3 Combustion or burning (fast oxidation) CH 4 + 2O 2  CO 2 + 2H 2 O Food spoiling (banana turns brown)

14. Obj. 2.c. - Motion A distance vs. time graph shows an objects’ speed (velocity). constant speed moving away at rest constant speed moving toward

15. Obj. 2c - Acceleration : change in motion A speed vs. time graph shows an object’s acceleration.  Label each: speeding up constant speed slowing down

16. Obj. 2f - Newton’s Laws  1 st law (law of inertia): Tells what happens to an object’s motion when balanced forces act on it: An object in motion will remain in motion, and an object at rest will remain at rest. Car stops, but your body moves forward An object moving in space will continue (comet)

17. Obj 2f - 2 nd Law of Motion  2 nd law (F=ma): Tells what happens to an object’s motion when unbalanced forces act on it: an object’s acceleration depends on its mass and the amount of force exerted on it. Kick two balls with the same amount of force and the lighter ball will accelerate more. Kick the same ball with different amounts of force and the larger force will cause it to accelerate more.

18. Obj 2f - 3 rd Law of Motion  3 rd Law of Motion (action/reaction): for every action there is an equal and opposite reaction. bird flies, rocket lifts off, skater pushes off wall, balloon flies around

19. Obj. 2d Power Grids (Path of electricity through a power grid:  High-voltage electricity is generated at the power plant.  The electricity is transmitted by transmission and distribution lines.  Electricity goes through a transformer on the utility pole to lower the voltage before it enters the home.  If a customer generates electricity at home (solar panels, windmill), they can sell unused electricity to the power company for other customers to use.

20. Obj. 2e Electromagnetic Spectrum  Radio: TV/radio (lowest energy)  Microwave: used in cell phones, police radar, and for cooking  Infrared: heat/thermal  Visible: ROYGBIV (from longest to shortest wavelength)  Ultraviolet (UV)  Mostly blocked by ozone layer in atmosphere  damages skin cells, causes skin cancer  used to disinfect medical equipment and to kill bacteria and other microorganisms in drinking water  X-ray: pictures of bones/teeth; damaging to cells of living things  Gamma: treat cancer – highest energy

21. Obj. 2e Electromagnetic Spectrum