9.5 The Laws Governing Formulas and Names
The Law of Definite Proportions
Law of definite composition
A compound contains the same elements in
exactly the same mass proportions
regardless of the size or source of sample.
9.5 The Laws Governing Formulas and Names
The Law of Definite Proportions
Example…
Formula for magnesium sulfide __________
MgS
Ratio of Mg2+ to S2- ions ________
1:1
Ratio of Mg2+ to S2- mass _______________
24.305 : 32.066
For every ______
0.75 g of Mg2+ there are always
______
1 g of S2- in MgS
9.5 The Laws Governing Formulas and Names
The Law of Definite Proportions
Example…
If you had 100 g of MgS the mass ratio
Mg:S is __________
0.75 : 1
If you had 200 g of MgS the mass ratio
Mg:S is __________
0.75 : 1
Does MgS obey the Law of Definite
Proportions? _________
Y
MASS RATIO ALWAYS
0.75 : 1
9.5 The Laws Governing Formulas and Names
The Law of Multiple Proportions
Law of multiple proportions
Applies to different compounds made from
the same elements (e.g. NO2 and N2O4 )
Mass ratio for the same elements in
different compounds can be expressed in
small whole numbers.
9.5 The Laws Governing Formulas and Names
The Law of Multiple Proportions
Law of multiple proportions
Formula for carbon monoxide __________
CO
Mass ratio of O to C ____________________
16 : 12.011 → 1.33 : 1
CO2
Formula for carbon dioxide __________
Mass ratio of O to C ____________________
32 : 12.011 → 2.66 : 1
9.5 The Laws Governing Formulas and Names
The Law of Multiple Proportions
Law of multiple proportions
CO
1.33 g : 1 g
O:C
CO2
2.66 g : 1 g
O:C
Mass ratio of C in CO to C in CO2
1 g : 1 g → 1 : 1 (small whole number!!)
______________________________________________________
Mass ratio of O in CO2 to O in CO
2.66
g : 1.33 g → 2 : 1 (small whole number!!)
______________________________________________________
9.5 The Laws Governing Formulas and Names
Examples
Carbon reacts with oxygen to form two compounds. Compound A contains 2.41 g
of carbon for each 3.22 g of oxygen. Compound B contains 6.71 g of carbon for
each 17.9 g of oxygen. For a given mass of oxygen, what is the lowest whole
number ratio of carbon in Compound A to Compound B?
COMPOUND A
COMPOUND B
C
2.41 g
6.71 g
O
3.22 g
17.9 g
0.75 g C in A
0.37 g C in B
2.41 g C in A
6.71 g C in B
3.22 g O in A
17.9 g O in B
0.75 g C in A
0.37 g C in B
1 g O in A
1 g O in B
“A GIVEN MASS OF OXYGEN”
2 g C in A
1 g C in B
LOWEST RATIO IS 2:1
9.5 The Laws Governing Formulas and Names
Examples
Lead forms two compounds with oxygen. Compound A contains 2.98 g of lead
and 0.461 g of oxygen. Compound B contains 9.89 g of lead and 0.763 g of
oxygen. For a given mass of oxygen, what is the lowest whole number ratio of
lead in Compound A to Compound B?
COMPOUND A
COMPOUND B
Pb
2.98 g
9.89 g
O
0.461 g
0.763 g
6.46 g Pb in A
12.96 g Pb in B
2.98 g Pb in A
9.89 g Pb in B
0.461 g O in A
0.763 g O in B
6.46 g Pb in A
12.96 g Pb in B
1 g O in A
1 g O in B
“A GIVEN MASS OF OXYGEN”
1 g Pb in A
2 g Pb in B
LOWEST RATIO IS 1:2
Daily Challenge
• Explain how the ending of
a name determines the
type of compound you
have.
Chapter 9 Review
• Vocab
– Monatomic/polyatomic
– Cation/anion
– Acid/base
– Binary compounds (ionic/molecular)
•
•
•
•
Bohr Diagrams
Lewis Dot Structures
Identifying charge by Group #
Identifying metal/nonmetal
Chapter 9 Review
• Naming
– When to use roman numerals
– When to use prefixes
• Ionic vs. Molecular
• Difference between name endings
– ide
– ate
– ite
Chapter 9 Review
• How to identify
– Acid/base/neither
– Molecular/ionic
•
•
•
•
•
•
Laws of multiple proportions
Laws of definite proportions (composition)
Table (like homework) ~10 compounds
Formula from name & Name from formula ~40
Draw Bohr diagrams and Lewis Dots
Mass ratio problem
Vocab
Ions
Formulas Names
Misc
100
100
100
100
100
200
200
200
200
200
300
300
300
300
300
400
400
400
400
400
500
500
500
500
500
VOCABULARY – 100
CONSISTS OF A GROUP OF
ATOMS WITH A POSITIVE
OR NEGATIVE CHARGE
POLYATOMIC ION
VOCABULARY – 200
ATOM OR GROUP OF
ATOMS HAVING A
NEGATIVE CHARGE
ANION
VOCABULARY – 300
PRODUCES A
HYDROXIDE ION WHEN
DISSOLVED IN WATER
BASE
VOCABULARY – 400
TYPE OF COMPOUND
FORMED BETWEEN A
METAL AND NON-METAL
IONIC
VOCABULARY – 500
TO SUBDIVIDE (AS ENERGY)
INTO SMALL BUT
MEASURABLE INCREMENTS
QUANTIZE
IONS – 100
ALUMINUM ION
Al+3
IONS – 200
SULFITE
SO3-2
IONS – 300
AMMONIUM
NH4+1
IONS – 400
MnO4-1
PERMANGANATE
IONS – 500
PHOSPHITE
PO3-3
FORMULAS – 100
ALUMINUM HYDROXIDE
Al(OH)3
FORMULAS – 200
Diboron tetrachloride
B2Cl4
FORMULAS – 300
Lithium phosphate
Li3PO4
FORMULAS – 400
Manganese (IV) carbonate
Mn(CO3)2
FORMULAS – 500
SULFUROUS ACID
H2SO3
COMPOUND NAMES – 100
C2 H4
Dicarbon tetrahydride
COMPOUND NAMES – 200
Cu3PO4
Copper (I) phosphate
COMPOUND NAMES – 300
MgN
Magnesium Nitride
COMPOUND NAMES – 400
H3 S
Hydrosulfuric Acid
COMPOUND NAMES – 500
H3PO3
Phosphorous acid
MISCELLANEOUS – 100
THE LEWIS DOT STRUCTURE
FOR ALUMINUM
Al
MISCELLANEOUS – 200
THE BOHR DIAGRAM FOR
THE FLUORINE ATOM
9 p+ 2 e-
7 e-
MISCELLANEOUS – 300
THIS ARTIST HOLDS THE
RECORD FOR THE BIGGEST ALLTIME SALES FOR A SOLO ARTIST
MICHAEL JACKSON
MISCELLANEOUS – 400
GROUP OF ATOMS THAT ARE
THE MOST ABUNDANT AND
FORM BOTH IONIC AND
COVALENT BONDS
NON-METALS
MISCELLANEOUS – 500
“GUILTY UNTIL PROVEN
INNOCENT” IS THE
STANDARD FOR THIS
FEDERAL AGENCY
IRS