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 ElementsWhat are the Two Main Classes of Elements?Metals and Nonmetals Noble Elements

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

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?

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

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

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

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

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

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

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

Writing and Naming fromulas

• Naming Formulas• Writing Formulas

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

Example OneName the formula Fe2(CrO4)3 Step #1 Find The + Ion(s).

Iron(II) Fe+2

Iron(III) Fe+3

Example OneStep #2 Find The - Ion(s)

Chromate CrO4-2

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

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

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

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

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

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