Chapter 9Chemical Names & Formulas

Name & Formula 2-D Structure 3-D Representation

Ammonium NH4+

Hydroxide OH–

Nitrate NO3–

Nitrite NO2–

Acetate C2H3O2 –

or CH3COO

Carbonate CO32-

Sulfate SO42-

Sulfite SO32-

Phosphate PO43-

+ 1 cation

– 2 anions

– 1 anions

– 3 anion

Naming Compounds• Naming compounds is essential in

chemistry.• There are 2 types of chemical

compounds• Molecular and Ionic

• You need to know the type of compound before you can name it.

Molecular Compounds

• Atoms of different elements combine to form compounds.

• Molecular Compounds—compounds composed of molecules.• Tend to have low melting and boiling

points• Many are gases or liquid at room temp.• Are composed of 2 or more nonmetals.• Example: 1 atom of carbon can react

with 1 atom of oxygen to produce 1 molecule of Carbon Monoxide (CO)

Molecular Formulas• Molecular Formula—shows the kinds

and numbers of atoms present in a molecular compound.• Includes the elements present and the

number of each as a subscript.• If there is only 1, the subscript is omitted.

Sec 5: Molecular Compounds• Binary compounds—compounds

containing 2 elements.• Binary molecular compounds—contain 2

nonmetal elements.• Composed of molecules—not ions.

• 2 nonmetals can combine in more than 1 way!• CO2 is a gas that we breathe out.• CO is a colorless, odorless, & deadly gas

• Both are carbon oxides, but it is important to distinguish between them.

Naming Molecular Compounds

• Prefixes distinguish between different compounds• They tell the number of each element

present in each molecule.

• For the second element, change the ending to -ide

1-mono2-di3-tri4-tetra5-penta

6-hexa7-hepta8-octa9-nona10-deca

Examples: CO2 is carbon dioxideCO is carbon monoxide

Notice: the mono prefix is omitted on the first element.

Formulas of Molecular Compounds

•Given the name, writing formulas is easy!!

•Use the prefixes to tell you the subscript of each element in the formula.•Example: tetraiodine nonoxide

•I4O9

Lets try some examples• Given the formula, write the name for

the following molecular compounds.

•N2O•Dinitrogen monoxide

•PCl3•Phosphorus trichloride

•SF6

•Sulfur hexafluoride

•CS2

•Carbon disulfide

More examples• Given the name, write the formula for

the following molecular compounds.•Nitrogen trifluoride

•NF3

•Disulfur dichloride•S2Cl2

•Dinitrogen tetroxide•N2O4

•Phosphorus pentafluoride•PF5