understanding formulas
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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. - PowerPoint PPT PresentationTRANSCRIPT
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Understanding Formulas
• Two Classes of Elements• What Are Stable Elements?• Stabilizing Sodium• Stabilizing Oxygen• Sodium Loses electrons to Oxygen• Oxidation Numbers• Key Elements• Examples
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Two Classes of ElementsWhat are the Two Main Classes of Elements?Metals and Nonmetals Noble Elements
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What Makes Elements Stable?
(Lose e-1)
(Gain e-1)
Losing or Gaining e-1.Do metals Lose or Gain e-1?Do nonmetals Lose or Gain e-1?
0 +1 +2 +3 +4 +5 +6 +7 +8 +9 +10-10 -9 -8 -7 -6 -5 -4 -3 -2 -1
Oxidation
Reduction
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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 (+11) (-10) +1
Oxidation or reduction?
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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
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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
two Na
one O
High Electronegativity
Low Electronegativity
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Oxidation Numbers• All elements Lose or Gain e-1.• Some have multiple loss or gain possibilities.
Fe+2 Fe+3 S-2 S+4 S+6
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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
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Example OneFinding Oxidation Numbers
2 (+3)+ 3(S) = Zero
sum of the oxidation #’s =
Find Ox #’s for Al2S3?
zero
2 (Al)+ 3(S) = Zero
S = -2
+3 -2
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Example TwoFinding Oxidation Numbers
sum of the oxidation #’s = zero+2 -2
Find Ox #’s for Ca3(PO4)2?
3(Ca)+ 8(O) = Zero
+5
2(P)+3(+2)+ 8(-2) = Zero2(P)+
= +5P
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Finding Oxidation #’s for Compounds
+1 -2
+1+5 -2H3PO4
H2O
HNO3
+1+5 -2
H2SO4
+1 -2+6
Hg2SO4
+6+1 -2
Na2Cr2O7
+1 +6 -2
H2CO3
+1 -2+4
(NH4)2CO3
-3 +1+4 -2
Ca3(AsO4)2
+2 +5 -2
Fe2(SO4)3
+6+3 -2
Ba(ClO4)2
+2 +7 -2
Al2(CO3)3
+3 +4 -2
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Writing and Naming fromulas
• Naming Formulas• Writing Formulas
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Naming Inorganic Salts• TWO parts to the name• 1) Cation• 2) Anion• Cation Examples
• Anion Examples
PositiveNegative
Ca+2 Al+3
Fe+2 Na+1
Cl-1 NO3-1 SO4
-2 N-3
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Example OneName the formula Fe2(CrO4)3 Step #1 Find The + Ion(s).
Iron(II) Fe+2
Iron(III) Fe+3
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Example OneStep #2 Find The - Ion(s)
Chromate CrO4-2
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Fe2(CrO4)3 Fe+2 Fe+3 CrO4-2Iron(II) ChromateIron(III)
Fe+2 CrO4-2
Iron(II) Chromate
(+2) (-2)Y+ = 0X=1 Y=1
FeCrO4
X
(+2) (-2)1+ = 01
Fe+3 CrO4-2
Iron(III) Chromate
(+3) (-2)Y+ = 0X=2 Y=3
X
(+3) (-2)3+ = 02
Fe2(CrO4)3
Example One
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Al2(CO3)3 Al+3 CO3-2 CarbonateAluminum
Al+3 CO3-2
Aluminum Carbonate
(+3) (-2)Y+ = 0X=2 Y=3
X
(+3) (-2)3+ = 02
Al2(CO3)3
Example Two
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Naming a Formula
Fe(IO4)2
Fe(IO4)3Iron(III) ( )_( )_Fe+3 IO4
-131
Iron(II) ( )_( )_Fe+2 IO4-1
21
Name Fe(IO4)2
Sn(HPO4)2
SnHPO4tin(II) ( )_( )_Sn+2 HPO4
-222
tin(IV) ( )_( )_Sn+4 HPO4-2
42
Name Sn(HPO4)2
periodateperiodate
hydrogen phosphatehydrogen phosphate
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Sn3(BO3)4 Sn+4 BO3-3 BorateTin(IV)
Sn+4 BO3-3
Tin(IV) Borate
(+4) (-3)Y+ = 0X=3 Y=4
X
(+4) (-3)4+ = 03
Naming Example Three
Sn3(BO3)4( )_( )_Sn+4 BO3
-343
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Writing a Formula From a Name
AlPO3
Na2CO3Sodium Carbonate ( )_( )_Na+1 CO3
-212
Aluminum phosphite ( )_( )_Al+3 PO3-3
33
Ca3(AsO4)2Calcium Arsenate ( )_( )_Ca+2 AsO4
-323
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Writing a Formula From a Name
H3PO4
LiNO3Lithium Nitrate ( )_( )_Li+1 NO3
-111
Hydrogen Phosphate ( )_( )_H+1 PO4-3
13
Ca3(AsO4)2
(NH4)2CO3Ammonium carbonate ( )_( )_NH4
+1 CO3-2
12Calcium Arsenate ( )_( )_Ca+2 AsO4
-323
Hg2SO4
Fe(IO4)3Iron(III) periodate ( )_( )_Fe+3 IO4
-131
Mercury(I) Sulfate ( )_( )_Hg2+2 SO4
-222
Na2Cr2O7
Ba(ClO4)2Barium Perchlorate ( )_( )_Ba+2 ClO4
-121
Sodium Dichromate ( )_( )_Na+1 Cr2O7-2
12
Pb(SO4)2Lead(IV) Sulfate ( )_( )_Pb+4 SO4
-242
(Cation+?)X(Anion-?)Y (+?) (-?)Y+ = 0X
Lowest Whole Number RatioIf X or Y is 2 or greater...
and the ion is polyatomic.Ba+2 Cr2O7
-2 Hg2+2 Pb+4