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Unit One

Unit One. Notes #1 Unit One. Two Classes of Elements Periodic Table Info? What Are Stable Elements? Oxidation/Reduction Oxidation Numbers Key Elements and Examples Pgs 158-165. Draw a picture of an Atom. For a chemical RXN to occur, two atoms MUST collide. Since

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Unit One

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  1. Unit One

  2. Notes #1 Unit One • Two Classes of Elements • Periodic Table Info? • What Are Stable Elements? • Oxidation/Reduction • Oxidation Numbers • Key Elements and Examples • Pgs 158-165

  3. Draw a picture of an Atom For a chemical RXN to occur, two atoms MUST collide. Since the electrons are on the outside, then it is only the electrons that are involved !!! Electrons are either LOST OR GAINED

  4. Two Classes of Elements • What are the Two Main Classes of Elements? • Metals and Nonmetals (Stair-Step)

  5. What information doe the Periodic Table give us? Atomic Number # Protons = # of Electrons Electron structure Mass Number = # P + # N

  6. So any Atom as no charge • The atomic number tells us the number of protons (+ charges) AND the number of electrons (- charges) . • If you add all the charges up in an atom, they will equal ZERO. • An ATOM has NO NET Charge !!!

  7. If we start with an Atom….. • And it gains electrons, what happens to its’ charge? • It becomes negative • And it loses electrons, what happens to its’ chare? • It becomes positive. • If an atom becomes + or – we call it an ION

  8. We can only change the # of electrons • If we were to try to change the number of protons, in the nucleus ….things have a tendency of going BOOM ! That is a nuclear reaction. So most chemical reactions involve the LOSS or GAIN of electrons • OXIDATION = Loss of electrons • REDUCTION = Gain of electrons

  9. What Makes Elements Stable? • Eight Electrons…… we will see this often • Noble Gases (electronically stable) • He, Ne, Ar, Kr, Xe, and Rn • Lose or Gain to get 8e-1 (to become stable) • Do metalsLose or Gain electrons? • Do nonmetalsLose or Gain electrons? (Lose) (Gain)

  10. Oxidation Numbers • All elements Lose or Gain e-1. • Some have multiple loss or gain possibilities. S-2 Fe+2 Fe+3 S+4 S+6

  11. Key Elements • (99%) H+1 H-1 • (99%)O-2 O-1 • (Always) Li+1, Na+1, K+1, Rb+1, Cs+1, Fr+1 • (Always) Be+2, Mg+2, Ca+2, Ba+2, Sr+2, Ra+2 • (Always) Al+3 • (with only a metal) F-1, Cl-1, Br-1, I-1 • (NO3-1) ion is always +5 • (SO4-2) ion is always +6

  12. Example One • Find the oxidation numbers. • Al2S3 • Algebra is useful! • Al+3key element • 2(+3) + 3(S)=0 • S= -2 2(Al) + 0 3(S)=

  13. Example Two • Find the oxidation numbers. • Ca(NO3)2 • Algebra is useful ! • Ca+2 and O-2key elements • (+2)+2(N)+6(-2)=0 • (+2)+2(N)+(-12)=0 • 2(N)+(-10)=0 • 2(N)=10 • N= +5 (Ca)+ 6(O)= 2(N)+ 0

  14. Finding Oxidation #’s for Compounds +1 -2 +1 +4 -2 H2O H2CO3 +1 +5 -2 -3 +1 +4 -2 H3PO4 (NH4)2CO3 -2 +2 +5 +1 +5 -2 Ca3(AsO4)2 HNO3 +1 -2 +3 +6 +6 -2 H2SO4 Fe2(SO4)3 +1 +6 -2 +2 -2 +7 Hg2SO4 Ba(ClO4)2 +3 +4 -2 +6 +1 -2 Na2Cr2O7 Al2(CO3)3

  15. Now it is time for class work !!! • A101: paper practice (Work Together) • It will be due at beginning of class next time • Ready Set Break !!!

  16. So Let’s Review • When we are assigning oxidation numbers: If we are dealing with a molecule and there is no charge, the sum of all the oxidation numbers will add to zero. If we are dealing with a Polyatomic ion, then the sum of all of the oxidation numbers adds up to that charge +2 +5 -2 +6 -2 Ca3(PO4)2 Cr2O7-2

  17. CA101 Assigning oxidation #’s Turn on Mac: double click on the MAC folder on the desktop. Open the Redox folder and click on the yellow, red and blue icon. Choose the top button: finding oxidation Numbers in triatomic compounds.

  18. You will do 15 problems and show all your algebra work on CA101 !!!!! I will show you how today. If you click on KEY ELEMENTS Your resource paper is online in The program.

  19. Please get A101 and CA 101 Stamped Today !!!Once you are done we will introFormula Writing

  20. Notes Two Unit One • Naming Inorganic Salts • Example One • Example One Thinking • Example Two • Computer Assignment One

  21. Naming Inorganic Salts Positive Negative • TWO parts to the name • 1) Cation • 2) Anion • Cation Examples • Ca+2 • Al+3 • Fe+2 • Na+1 • Anion Examples • Cl-1 • NO3-1 • SO4-2 • N-3

  22. Example One • Name the formula Fe2(CrO4)3 • Step #1 Find The + Ion(s). Iron(II) Fe+2 Iron(III) Fe+3

  23. Example One • Step #2 Find The - Ion(s) Chromate CrO4-2

  24. Example One Iron(II) Fe+3 Iron(III) CrO4-2 Fe2(CrO4)3 Fe+2 Chromate Chromate Chromate Iron(II) Iron(III) Fe+2 Fe+3 CrO4-2 CrO4-2 X (+2) + Y = 0 X (+3) + Y = 0 (-2) (-2) X=1 Y=1 X=2 Y=3 1 (+2) + 1 = 0 2 (+3) + 3 = 0 (-2) (-2) Fe Fe2(CrO4)3 CrO4

  25. Example Two Al+3 Aluminum CO3-2 Al2(CO3)3 Carbonate Carbonate Aluminum Al+3 CO3-2 X (+3) + Y = 0 (-2) X=2 Y=3 2 (+3) + 3 = 0 (-2) Al2(CO3)3

  26. In class work today: • Work on A102 • Use you Cation/Anion Sheet • Remember to fnd the charges of the ions and make sure that they add up to zero to write the formula. • When you are naming a formula you always write the + ion first then the -ion

  27. CA 102:Writing FormulaCA 103: Naming Compounds • NAMING IONIC COMPOUNDS LEVELs ONE AND TWO • Get A102 , CA 102, CA103 all stamped today. • Now let’s look at some examples at how to write Formulas from a name. You need to have your Cation/Anion sheet out. • Homework for tonight, read L101 Electrolysis of water Lab, we will do that next class !!!!

  28. (Cation+?)X(Anion-?)Y X (+?) + Y = 0 (-?) Writing a Formula From a Name If X orY is 2 or greater... Lowest Whole Number Ratio and the ion is polyatomic. Ba+2 Cr2O7-2 Hg2+2 Pb+4 ( )_( )_ Lithium Nitrate Li+1 1 NO3-1 1 LiNO3 ( )_( )_ Hydrogen Phosphate H3PO4 H+1 3 PO4-3 1 ( )_( )_ Ammonium carbonate NH4+1 CO3-2 1 2 (NH4)2CO3 ( )_( )_ Calcium Arsenate Ca3(AsO4)2 2 Ca+2 3 AsO4-3 ( )_( )_ Iron(III) periodate Fe+3 1 IO4-1 3 Fe(IO4)3 ( )_( )_ Mercury(I) Sulfate Hg2SO4 Hg2+2 2 SO4-2 2 ( )_( )_ Barium Perchlorate Ba+2 ClO4-1 2 1 Ba(ClO4)2 ( )_( )_ Sodium Dichromate Na2Cr2O7 1 Na+1 2 Cr2O7-2 ( )_( )_ Lead(IV) Sulfate Pb(SO4)2 4 Pb+4 2 SO4-2

  29. Notes Three Unit One • Standard Amounts • One Gopher • One Mole • Formula mass • Percent Composition • Empirical Formula

  30. Standard Amounts • How many dollars is… • A) 120 pennies? • 1.2 dollars • B) 2 quarters? • 0.5 dollars • C) 15 nickels? • 0.75 dollars • How many dozens is… • D) 48 eggs? • 4 dozen • E)18 apple fritters • 1.5 dozen

  31. One Dozen • You KNOW it equals 12 items • What if I asked you to • Go into the lab and get • 12 Carbon atoms?

  32. One Mole • One mole is 6.022x10+23 items. • Each element on the period table has a mass per mole. N 14.0g 6.022x10+23atoms 16.0g 6.022x10+23atoms O 12.0g 6.022x10+23atoms C • How many moles are in each? • How many atoms are in each? N 7.0g =0.50m x6.022x10+23atoms/m ÷14.0g/m =3.01x10+23atoms O =0.25m ÷16.0g/m x6.022x10+23atoms/m 4.0g =1.51x10+23atoms C =1.50m 18.0g ÷12.0g/m x6.022x10+23atoms/m =9.03x10+23atoms

  33. Calculations Bases on Chemical Formulas Formula mass (Molecular Mass or Gram-Formula Mass) Empirical Formula Percent Composition

  34. Rounding Atomic Mass 12.0 C 12.011 55.8 Fe 55.847 16.0 O 15.9994 209.0 Bi 208.980837 39.1 K 39.0983 197.0 Au 196.96654 190.2 Os 190.23 24.3 Mg 24.3050 23.0 Na 22.98968

  35. Formula Mass Example One Calculate the formula mass for 1 mole of C6H12O6. # E Mass 12.011 C 12.0 = 72.0 6 x 1.0079 H 12 x 1.0 = 12.0 15.9994 O 6 x 16.0 = 96.0 180.0g/mol How many molecules of C6H12O6 is 180.0g/mol? 6.022x10+23 molecules

  36. Empirical Formula • By definition, it is the lowest WHOLE number ratio of elements in a compound. • It may or may not be the actual MOLECULAR FORMULA. • But is does so the whole number ratio of elements in a compound. • HO = empirical formula of Hydrogen Peroxide but H2O2 is the molecular Formula

  37. Empirical Formula Example One What is the empirical (simplest) formula containing 36.8% N, 63.2% O? 1) Calculate moles of each element. 3) Write the formula Q Mass E Mass N 2.63 mol N 14.0067 36.8 g ÷ 14.0 = 15.9994 O 63.2 g ÷ 16.0 = 3.95 mol O 2) Calculate the lowest ratio. (divide by small moles) Moles E Lowest Ratio N 1.00 2.63 mol N ÷ 2.63 mol = O 3.95 mol O ÷ 2.63 mol = 1.50 X by 2 to get whole numbers N2O3

  38. Percent Composition Example One 1)Calculate the formula mass for 1 mole of H2O # E Mass Calculate the percentage composition of H2O. H 2.0 2 x 1.0 = 1.0079 O 1 x 16.0 = 16.0 15.9994 18.0g/mol 2) Divide each contribution by the total mass. ( x 100) = 11% H 0.11 2.0 ÷ 18.0 = Answer ( x 100) = 88.9% O 16.0 ÷ 18.0 = 0.889 3) Add the percentages to check work. 11% 88.9% 100.%

  39. Empirical Formula Example Two What is the empirical (simplest) formula containing 69.58% Ba, 6.090% C, 24.32% O? 1) Calculate moles of each element. 3) Write the formula Q Mass E Mass Ba 0.50666 mol Ba 69.58 g ÷ 137.33 = C 6.090 g ÷ 12.01 = 0.50708 mol C O 24.32 g ÷ 16.00 = 1.520 mol O 2) Calculate the lowest ratio. E Moles Lowest Ratio Ba 0.50666 mol ÷ 1.000 0.50666 mol = C 0.50708 mol ÷ 0.50666 mol = 1.001 O 1.520 mol ÷ 0.50666 mol = 3.00 X by 1 to get whole numbers BaCO3

  40. Percent Composition Example Two 1)Calculate the formula mass for 1 mole of Fe(ClO4)3. # E Mass Calculate the percentage composition of Fe(ClO4)3. 55.847 Fe 55.8 1 x 55.8 = 35.453 Cl 106.5 3 x 35.5 = 15.9994 12 x O 16.0 = 192.0 354.3g/mol 2) Divide the each contribution by the total mass. ( x 100) = 15.8% Fe 0.1575 55.8 ÷ 354.3 = Cl 0.3006 106.5 ÷ 354.3 = ( x 100) = 30.06% Answer O 192.0 ÷ 354.3 = ( x 100) = 54.19% 0.5419 3) Add the percentages to check work. 15.8 % 30.1 % 54.2 % 100.1%

  41. Formula Mass Example Three Calculate the formula mass for 1 mole of Al2O3 # E Mass Al 54.0 2 x 27.0 = 26.98154 O 3 x 16.0 = 48.0 15.9994 102.0g/mol How many molecules of Al2O3 is102.0g/mol? 6.022x10+23 molecules

  42. Formula Mass Example Two Calculate the formula mass for 1 mole of CaCO3. # E Mass 40.078 Ca 40.1 = 40.1 1 x 12.011 C 1 x 12.0 = 12.0 15.9994 O 3 x 16.0 = 48.0 100.1g/mol How many molecules of CaCO3 is100.1g/mol? 6.022x10+23 molecules

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