Law of definite compositionA compound contains the same elements in

exactly the same mass proportions

regardless of the size or source of sample.

The Law of Definite Proportions9.5 The Laws Governing Formulas and Names

Example…

The Law of Definite Proportions9.5 The Laws Governing Formulas and Names

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 ______ g of Mg2+ there are always ______ g of S2- in MgS

0.751

Example…

The Law of Definite Proportions9.5 The Laws Governing Formulas and Names

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

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.

The Law of Multiple Proportions9.5 The Laws Governing Formulas and Names

Law of multiple proportions

The Law of Multiple Proportions9.5 The Laws Governing Formulas and Names

Formula for carbon monoxide __________ CO

Mass ratio of O to C ____________________ 16 : 12.011 → 1.33 : 1

Formula for carbon dioxide __________ CO2

Mass ratio of O to C ____________________ 32 : 12.011 → 2.66 : 1

Law of multiple proportions

The Law of Multiple Proportions9.5 The Laws Governing Formulas and Names

CO CO2

1.33 g : 1 gO : C

2.66 g : 1 gO : 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!!)

Examples9.5 The Laws Governing Formulas and Names

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

3.22 g O in A

2.41 g C in A

17.9 g O in B

6.71 g C in B

1 g O in A

0.75 g C in A

1 g O in B

0.37 g C in B

“A GIVEN MASS OF OXYGEN”

0.37 g C in B

0.75 g C in A

1 g C in B

2 g C in A

LOWEST RATIO IS 2:1

Examples9.5 The Laws Governing Formulas and Names

COMPOUND A COMPOUND B

Pb 2.98 g 9.89 g

O 0.461 g 0.763 g

0.461 g O in A

2.98 g Pb in A

0.763 g O in B

9.89 g Pb in B

1 g O in A

6.46 g Pb in A

1 g O in B

12.96 g Pb in B

“A GIVEN MASS OF OXYGEN”

12.96 g Pb in B

6.46 g Pb in A

2 g Pb in B

1 g Pb in A

LOWEST RATIO IS 1:2

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?

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

C2H4

Dicarbon tetrahydride

COMPOUND NAMES – 200

Cu3PO4

Copper (I) phosphate

COMPOUND NAMES – 300

MgN

Magnesium Nitride

COMPOUND NAMES – 400

H3S

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 ALL-TIME 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