ChemistryChemistryHappy Birthday to Imani & Mark!Happy Birthday to Imani & Mark!

Naming and Writing Formulas for Naming and Writing Formulas for Molecular CompoundsMolecular Compounds

One milligram of gold is One milligram of gold is worth only about one cent, worth only about one cent, but one kilogram of gold is but one kilogram of gold is worth approximately worth approximately $12,500. The correct prefix $12,500. The correct prefix ( ( milli- milli- oror kilo- kilo-) makes quite ) makes quite a difference! Prefixes are a difference! Prefixes are important in chemistry, too. important in chemistry, too. The prefixes in the name of The prefixes in the name of a binary molecular a binary molecular compound tell you its compound tell you its composition.composition.

9.3

Naming Binary Naming Binary Molecular Molecular CompoundsCompounds

Naming Binary Molecular Naming Binary Molecular CompoundsCompoundsWhat does a prefix in the name What does a prefix in the name

of a binary molecular of a binary molecular compound tell you about the compound tell you about the compound’s composition?compound’s composition?

9.3

Carbon and oxygen combine Carbon and oxygen combine to form carbon monoxide to form carbon monoxide (CO) and carbon dioxide (CO) and carbon dioxide (CO(CO22), but these two invisible ), but these two invisible gases are very different.gases are very different.

9.3

Naming Binary Naming Binary Molecular Molecular CompoundsCompounds

Sitting in a room with small Sitting in a room with small amounts of COamounts of CO2 2 in the air would in the air would not present any problems. If the not present any problems. If the same amount of CO were in the same amount of CO were in the room, you could die of room, you could die of asphyxiation. A naming system asphyxiation. A naming system that distinguishes between these that distinguishes between these two compounds is needed.two compounds is needed.

9.3

Naming Binary Naming Binary Molecular Molecular CompoundsCompounds

A prefix in the name of a binary A prefix in the name of a binary molecular compound tells how molecular compound tells how many atoms of an element are many atoms of an element are present in each molecule of the present in each molecule of the compound.compound.

9.3

Naming Binary Naming Binary Molecular Molecular CompoundsCompounds

Some guidelines for naming Some guidelines for naming binary molecular compounds:binary molecular compounds:

Name the elements in Name the elements in the order listed in the the order listed in the formula.formula.

Use prefixes to indicate Use prefixes to indicate the number of each the number of each kind of atomkind of atom..

9.3

Naming Binary Naming Binary Molecular Molecular CompoundsCompounds

Omit the prefix Omit the prefix mono-mono- when the formula contains when the formula contains only one atom of the first only one atom of the first element in the name.element in the name.

The suffix of the name of The suffix of the name of the second element is -the second element is -ideide..

9.3

Naming Binary Naming Binary Molecular Molecular CompoundsCompounds

Writing Formulas for Writing Formulas for BinaryBinary

Molecular CompoundsMolecular Compounds

Writing Formulas for Binary Writing Formulas for Binary Molecular CompoundsMolecular Compounds

How do you write the How do you write the formula for a binary formula for a binary molecular compound?molecular compound?

9.3

Use the prefixes in the Use the prefixes in the name to tell you the name to tell you the subscript of each element subscript of each element in the formula. Then write in the formula. Then write the correct symbols for the the correct symbols for the two elements with the two elements with the appropriate subscripts.appropriate subscripts.

9.3Writing Formulas for Writing Formulas for

BinaryBinaryMolecular Molecular

CompoundsCompounds

Silicon carbide is a hard material Silicon carbide is a hard material like diamond. The name like diamond. The name silicon silicon carbidecarbide has no prefixes, so the has no prefixes, so the subscripts of silicon and carbon subscripts of silicon and carbon must be one. Thus, the formula must be one. Thus, the formula for silicon carbide is SiC.for silicon carbide is SiC.

9.3

Writing Formulas for Writing Formulas for BinaryBinary

Molecular Molecular CompoundsCompounds

Assess students’ understanding of Assess students’ understanding of the concepts in Sectionthe concepts in Section 9.3.9.3.

9.3 Section Quiz.9.3 Section Quiz.

9.3 Section Quiz.9.3 Section Quiz.

1.1. Which of the following Which of the following compounds is named compounds is named INCORRECTLY?INCORRECTLY? CSCS22, carbon disulfide, carbon disulfide

BClBCl33, boron trichloride, boron trichloride

IFIF77, iodine heptafluoride, iodine heptafluoride

PClPCl55, phosphorus hexachloride, phosphorus hexachloride

2.2. Which of the following molecular Which of the following molecular compounds is named INCORRECTLY?compounds is named INCORRECTLY? SbClSbCl33, antimony trichloride, antimony trichloride

CC22OO55, dicarbon pentoxide, dicarbon pentoxide

CFCF44, carbon tetrafluoride, carbon tetrafluoride

HH33As, hydrogen arsenideAs, hydrogen arsenide

9.3 Section Quiz.9.3 Section Quiz.

3.3. The correct formula for The correct formula for tetraphosphorus trisulfide istetraphosphorus trisulfide is PP33SS44

SS33PP44

PP44SS33

SS44PP33

9.3 Section Quiz.9.3 Section Quiz.

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