Bell work 10/23

1. Bell work 10/23 Which subatomic particle determines the reactivity of groups on the periodic table? Compare/contrast an ionic and covalent bond. STUDY GUIDE IS ON GOOGLE CLASSROOM TO HELP YOU STUDY FOR THE QUARTERLY!

2. Commonly missed test question An element X, contains 14 protons, 15 neutrons, and 14 electrons. Which is MOST LIKELY the same as element X? • Element A: 13 P, 15 N, and 14 E • Element B: 14 P, 14 N, and 14 E • Element C: 15 P, 14 N, and 15 E Why??

3. Practice problem Sam finds a block made from an unknown element. Which is the BEST way to determine which element was used to create the block? • Test the malleability • Determine the mass of the block • Calculate the density of the block • Observe the reaction between the block and a nonmetal

4. Physical & Chemical changes can change matter, BUT…THE REAL QUESTION IS: During those changes, is any matter created or destroyed?

5. Law of Conservation of Mass/Matter Law of Conservation of Mass/Matter- Matter cannot be created or destroyed, it can only change form. So where does the wood go?

6. Law of Conservation of Mass NaF Na F IN OTHER WORDS… What goes in, must come out!

7. Open System/Reaction • The container in which the reaction is performed is open - matter may escape

8. Closed System/Reaction • The container in which the reaction is being performed is closed so all of the matter will be contained – nothing escapes

9. What does the Law of Conservation of Mass/Matter state?

10. Law of Conservation of Mass is the KEY to Balancing Chemical Equations! NaF Na F REMEMBER: What goes in, must come out!

11. Chemical Reactions Reactants – Elements OR compounds present at the beginning of a chemical reaction Product – Compounds formed by a chemical reaction

12. REACTANTS PRODUCT

13. Balancing Chemical Equations • Since matter can neither be created or destroyed, the mass/amount of reactants must always equal the mass/amount of products

14. What are the Reactants?What are the Products? NaF Na F The arrow indicates that a change has occurred

15. Balancing Chemical Equations • Before (Reactants) • After (Product) NaF Na F Na = 1 Na = 1 F = 1 F = 1

16. Components of a Chemical Equation(Label your diagram) Chemical formula for new compound Chemical formulas for elements → 2H2 + O2 2H2O Coefficient Subscript Coefficient Subscripts (Reactants) (Products)

17. What is that little number? Subscript – • Shows how many atoms of an element are in a compound. • When there is NO subscript there is only 1 atom of that element. O2 NaCl NH4 K5N4C2

18. What is that big number in front? Coefficient – • The number of molecules (compounds) involved in a chemical reaction H2 O2 H2 H2O 2 2 H2 O2

19. So the coefficient tells you the number of molecules, but what about each atom? • You must multiply…it is like the distributive property in math! 2NH4 5H2O 3O2 2Li3F2 2Ca(OH)2 2K5N4C2

20. Balloon Lab Lets try it!!!

21. Rules for Balancing Chemical Equations 1. You CANNOTchange subscripts, you can ONLY change coefficients H2 + O2 2H2O 2. It does NOT have to look the same on both sides, it only has to be balanced 3. You CANNOT split compounds to write in a coefficient: HCl

22. Rules to Balancing Chemical Equations 4. Only multiply through when it is a compound because they have already bonded 2H + Cl 2HCl NO YES 5. If it is a capital letter, they are each a separate element: H, C, O If it is a capital letter followed by a lower case letter, it is all one element: Cl, Li, Si

23. Steps for Balancing Chemical Equations • 1. Divide the reactants from the productswith a line. • 2. Write down the chemical symbol of each of the elements on each side of the equation 2 H2 + O 2 2H2O H = O = H = O =

24. Steps to Balancing Chemical Equations • 3. Using the coefficients and subscripts write down the number of each element • 4. If they are not balanced change only the coefficients using trial and error. You will have to go back and forth between each side! 2 H2 + O 2 2H2O H = 4 O = 2 H = 4 O = 2

25. Lets Practice P + O2 P4O6

26. Lets Practice Na + O2 Na2O

27. Lets Practice Al2O3 Al + O2

28. Lets Practice Cl2 + KI KCl + I2

29. Equation 1 - Balance Box Answer P + O P4O10

30. Equation 2 - Balance Box Answer Cl₂ + NaBr NaCl + Br₂

31. Equation 3 - Balance Box Answer Cs + N₂ Cs3N

32. Equation 4 - Balance Box Answer CuCl₂ + H₂S CuS + HCl

33. Equation 5 - Balance Box Answer Al + HCl AlCl₃ + H₂

34. Law of Conservation of Mass (Matter)Analyzing Reactions • Some chemical reactions are ENDOTHERMIC = take “in” or absorb energy • Some chemical reactions are EXOTHERMIC = give “out” or produce energy How would you tell the difference?

35. An endothermic reaction takes “in” or absorbsenergy Causes temperature around it to cool (will feel cold) EXAMPLE:Photosynthesis (needs energy from the sun) Endothermic Reactions

36. Exothermic Reactions • An exothermic reaction gives “out” or produces energy (heat, light or sound) • Causes temperature around it to rise (feels warm/hot) • EXAMPLE: cellular respiration (gives energy to your cells)

37. Lets Practice: Part D - #1 Na + MgF2 NaF + Mg

38. Lets Practice: Part D - #2 Cl2 + KI KCl + I2 IMPORTANT: Cl = Chlorine K & I are 2 separate elements

39. Lets Practice: Part D - #3 HCl + NaOH NaCl + H2O

40. Lets Practice: Na + NaNO3 Na2O + N2

41. Lets Practice: PbBr2 + HCl HBr + PbCl2

42. Lets Practice: Na3P + CaF2 NaF + Ca3P2

43. Lets Practice: AlBr3 + K KBr + Al

44. 11/1 Bell work Balance the following equation: CaF2 + Li2SO4 CaSO4 + LiF

45. Key Sodium Bicarbonate- smooth, white powder Calcium Chloride- White, circular substance 2 tbs= 1.5 spoonfuls Phenol Red- changes yellow in the presence of ACID and changes blue in the presence of BASE. *Each group member will lead one experiment! READ DIRECTIONS!!

46. Bell work 11/2