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Science CASE 21 Review

Learn about chemical formulas, balancing equations, elements in the periodic table, chemical bonding, properties of acids and bases, and motion representation in graphs in physical science. Enhance your competency in physical science concepts.

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Science CASE 21 Review

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  1. Science CASE 21 Review Competency 2 Physical Science

  2. 2a Chemical Formulas • Chemical Formulas show a combination of chemical symbols & numbers that indicates which elements & how many atoms of each element are present in a compound • H2O (Water) • C6H12O6 (Sugar/glucose) • O2 (Oxygen Molecule) • CO2 (Carbon Dioxide) • N2 (Nitrogen Molecule) Subscript: # of atoms

  3. What is the molecule? • NaCl • H20 • C6H12O6 • O2 • CO2 • N2 • CH4

  4. Sample Question

  5. 2a. Law of Conservation of Mass • The Law of Conservation of Mass states that mass can neither be created nor destroyed

  6. Balancing an Equation • Ex. 2H2 + O2 2H2O Reactant Product

  7. 2.a. Balancing Equations • Zn + 2HCl ZnCl2 + H2 • How many hydrogen molecules will be produced if there is 1000 HCl molecules in the reactant side of this balanced equation?

  8. Obj. 2.a. Photosynthesis and Respiration Photosynthesis carbon dioxide + water + sunlight oxygen + glucose 6 CO2 + 6H2O 6O2 + C6H1206 Respiration oxygen + sugar carbon dioxide + water + energy 6O2 + C6H1206 6CO2 + 6 H2O

  9. Sample Question

  10. Sample Question

  11. Sample Question

  12. 2b. Elements are arranged in a Periodic Table • There are 18 columns • Columns contain a group or family of elements

  13. Element Families have similar chemical properties • Alkali Metals: Group 1; 1 valence electron • Alkaline Earth Metals: Group 2; 2 valence electrons • Halogens: Group 17; 7 valence electron • Noble Gases: Group 18; 8 valence electron

  14. Types of Elements • Metals • Nonmetals • Metalloids

  15. Metals • Found on the left side of the periodic table in groups 1-15 • Physical Properties of metals • Malleable: can be hammered or rolled into flat sheets or other shapes • Ductile: can be pulled out or drawn into a long wire • Conductivity: have the ability to transfer heat or electricity to another object • Some are magnetic (Iron, Cobalt, & Nickel) • Have luster (shine)

  16. Non-metals • Found on the right side of the periodic table • Physical properties are opposite of metal properties • Poor conductors of heat & electricity • Brittle: shatter easily • Dull

  17. Metalloids • Found along a stair-step pattern between the metals & non-metals beginning in group 13 • Ex. Silicon (Si)

  18. What other elements have similar properties to Phosphorus (#15)? • What type of element is calcium? • What group would an element that is brittle & not a good conductor of electricity be in? • What does the staircase divide?

  19. 2b. Chemical Bonds • Elements bond to other elements to become stable by having a full valence shell • Most elements need 8 valence electrons to become stable • Elements will become stable by losing, gaining, or sharing valence electrons

  20. Ionic Bonding • Ionic bonding: occurs when an atom that no longer has a neutral charge because it has lost or gained an electron • Typically between a Metal (looses) & Non-metal (gains) • Ex. Na+Cl-

  21. Covalent Bonding • Covalent bonds are chemical bonds that form from atoms that share valence electrons to become stable • Occurs between two or more nonmetals • Ex. H2 , Cl2 , H2O , C6H12O6

  22. 2b. Properties of Acids & Bases • An acid is a compound that produces hydrogen ions in water (H+) • A base is any compound that produces hydroxide ions (OH-) in water.

  23. Predicting Acids & Bases using the Periodic Table • H+ • combines with certain nonmetals (Halogens (group 17) • The weaker the bond the stronger the acid. • Ex. Fluorine & hydrogen (HF) weakest acid • Ex. Iodine & Hydrogen (HI) strongest acid Stronger acid

  24. Predicting Acids & Bases using the Periodic Table • hydroxide ion (OH-) • joins with a metal • group 1 (alkali metals) • group 2 (alkaline earth metals) • The weaker the bond the stronger the base. • Ex. Potassium Hydroxide (KOH) weakest base • Ex. Lithium Hydroxide (LIOH) Strongest base Stronger base

  25. pH scale • The further from 7 the stronger the acid or base • Litmus paper turns blue with bases & red acids

  26. What element will ionically bond with sodium (#9)? • What 2 elements can covalently bond? • Identify the following as an acid or a base • HI • LiOH • How many Sodiums will be needed to bond with one oxygen atom? • What type of bond will this be?

  27. Sample Question

  28. Sample Question

  29. Obj. 2c • Distinguish the motion of an object by its position, direction of motion, speed, and acceleration and represent resulting data in graphic form in order to make a prediction.

  30. Graphing Speed • Formula: Speed = distance÷ time (S=D/T) • Speed can be graphed on a distance-time graph • The steeper the line on a distance-time graph, the greater the speed

  31. 2.c. Speed Graphs: Identify the motion. A B C D

  32. Velocity • Velocity is the speed of an object and the direction of its motion.

  33. Acceleration • Acceleration occurs when an object changes its motion (velocity changes) • Speed up - 50m/h to 60m/h (positive) • Slow down – 45m/h to 40m/h (negative) • Acceleration is in the opposite direction of the motion • Change in direction – north to east

  34. Graphing Acceleration • Identify the Motion • A B C

  35. Example Graph

  36. Sample Question

  37. Sample Question

  38. Obj. 2f • Recognize Newton’s Three Laws of Motion and identify situations that illustrate each law • (e.g., inertia, acceleration, action, reaction forces).

  39. Newton’s first law • 2 parts • An object will remain at rest until an unbalanced force is applied to the object • An object in motion will remain in motion at a constant rate until an unbalanced force is applied to the object • Known as the “law of inertia” • Inertia is the tendency of an object to resistchange in its motion • Ex. Applying breaks in a car and your body goes forward

  40. Newton’s 2nd Law • Newton’s second law of motion connects force, acceleration, and mass • an object acted on by a force will accelerate in the direction of the force • acceleration equals net force divided by mass. • Ex. An empty skateboard verses a person standing on a skateboard: Which one will you have to push harder to go the same distance? • Formula: (a = fnet÷ m) or (fnet = m x a)

  41. Newton’s 3rd Law • Newton’s third law of motion states that forces always act in equal but opposite pairs called action/reaction forces • for every action there is an equal and opposite reaction. • Bounce a ball on the ground or playing pool

  42. Which law? • Using an oar to move a canoe • Pushing a swing with more force to move your big brother than you did with your little sister • Stopping a grocery cart and the cereal box slides forward 3rd 2nd 1st

  43. Sample Question

  44. Sample Question

  45. Obj. 2d (DOK 2 & 3) • Relate how electrical energy transfers through electric circuits, generators, and power grids, including the importance of contributions from Mississippi companies.

  46. DC versus AC Current • DC current is when the electrical charge moves in one direction • Ex. Batteries • Always flow from the negative terminal to the positive terminal. • AC current is when the electrical charge flows in one direction, then in the reverse direction over and over again • Ex. Electrical current from the power plant to your home

  47. Generating Electricity • Generators are devices that spin a coiled wire within a magnetic field to produce electricity • The mechanical energy of a spinning turbine is transformed into electrical energy for human use • Primary method for producing the electricity in homes, schools, & the community

  48. What spins the turbine • Energy is produced by burning fossil fuels to boil water produces steam that turns a turbine to generate electricity. • Burning fossil fuels causes a large amount of CO2 pollution

  49. Power Grids • A power gridis a transmission network that connects power plants to multiple Substations near a populated area.

  50. Transformers Device that transfers electrical energy from one circuit to another & changes the voltage by increasing or decreasing it

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