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Understanding Formulas

Understanding Formulas. Two Classes of Elements What Are Stable Elements? Stabilizing Sodium Stabilizing Oxygen Sodium Loses electrons to Oxygen Oxidation Numbers Key Elements Examples. Two Classes of Elements. Metals and Nonmetals . Noble Elements.

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Understanding Formulas

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  1. Understanding Formulas • Two Classes of Elements • What Are Stable Elements? • Stabilizing Sodium • Stabilizing Oxygen • Sodium Loses electrons to Oxygen • Oxidation Numbers • Key Elements • Examples

  2. Two Classes of Elements Metals and Nonmetals Noble Elements What are the Two Main Classes of Elements?

  3. What Makes Elements Stable? Losing or Gaining e-1. Do metalsLose or Gain e-1? Do nonmetalsLose or Gain e-1? Oxidation (Losee-1) +1 +2 +3 +4 -10 -9 -8 -7 -1 +10 0 +5 +6 +7 +8 +9 -6 -5 -4 -3 -2 Reduction (Gain e-1)

  4. Stabilizing Sodium • How many e-1 for Na? • 11e-1 • What is the noble element closest to Na? • Ne • How many e-1 for Ne? • 10e-1 • Sodium loses/gains how many electrons? • 1e-1 • Na Na+1 + e-1 • (protons) + (electrons)=charge Oxidation or reduction? (+11) (-10) +1

  5. Stabilizing Oxygen • How many e-1 for O? • 8e-1 • What is the noble element closest to O? • Ne • How many e-1 for Ne? • 10e-1 • Oxygen loses/gains how many electrons? • 2e-1 • O + 2e-1  O-2 Oxidation or reduction? • (protons) + (electrons)=charge (+8) (-10) -2

  6. Sodium Loses electrons to Oxygen • Na Na+1 + e-1 (Stable Like Neon) Ox or Red? • O + 2e-1 O-2 (Stable Like Neon) Ox or Red? • How many sodium atoms are needed to satisfy oxygen’s electron hunger? • 2e-1 means • How many oxygen atoms are needed to satisfy sodium’s electron loss? • 2e-1 means • Na2O High Electronegativity two Na Low Electronegativity one O

  7. 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

  8. 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

  9. Example OneFinding Oxidation Numbers zero sum of the oxidation #’s = -2 +3 Find Ox #’s for Al2S3? 2 (Al)+ 3 (S) = Zero 2 (+3)+ 3 (S) = Zero -2 S =

  10. Example TwoFinding Oxidation Numbers zero sum of the oxidation #’s = -2 +2 +5 Find Ox #’s for Ca3(PO4)2? 3 (Ca)+ 2 (P)+ 8 (O) = Zero 3 (+2)+ 2 (P)+ 8 (-2) = Zero P = +5

  11. 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

  12. Writing and Naming fromulas • Naming Formulas • Writing Formulas

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

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

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

  16. 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

  17. 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

  18. Naming a Formula Name Fe(IO4)2 ( )_( )_ Iron(III) periodate Fe+3 1 IO4-1 3 Fe(IO4)3 ( )_( )_ Iron(II) periodate Fe(IO4)2 Fe+2 1 IO4-1 2 Name Sn(HPO4)2 ( )_( )_ tin(II) hydrogen phosphate Sn+2 HPO4-2 2 SnHPO4 2 ( )_( )_ tin(IV) hydrogen phosphate Sn(HPO4)2 Sn+4 2 HPO4-2 4

  19. Naming Example Three Sn+4 Tin(IV) BO3-3 Sn3(BO3)4 Borate Borate Tin(IV) Sn+4 BO3-3 X (+4) + Y = 0 (-3) X=3 Y=4 3 (+4) + 4 = 0 (-3) ( )_( )_ Sn+4 3 BO3-3 4 Sn3(BO3)4

  20. Writing a Formula From a Name ( )_( )_ Sodium Carbonate Na+1 2 CO3-2 1 Na2CO3 ( )_( )_ Aluminum phosphite AlPO3 Al+3 3 PO3-3 3 ( )_( )_ Calcium Arsenate 2 Ca+2 3 AsO4-3 Ca3(AsO4)2

  21. (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

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