Chapter 6 Notes part III

Covalent Compounds

Covalent (Molecular) Compounds

So far, we have only talked about ionic compounds; compounds made of a metal and nonmetal.

Covalent (Molecular) Compounds

A covalent compound forms between two nonmetals.

These compounds occur because the nonmetals will share electrons to have a full last energy level.

Covalent (Molecular) Compounds

Since electrons are not lost or gained, the atoms are not considered ions, so they do not have a charge.

Naming Covalents

Because covalent compounds aren’t made of ions, you can’t use the oxidation number to predict how many atoms of each element are going to be in a covalent compound.

Naming Covalents

mono- one hexa- sixdi- two hepta-

seventri- three octa- eighttetra- four nona- ninepenta- five deca- ten

The following prefixes will be used.

Naming Covalents

1)Name the first element in the compound, and use a prefix if there is more than one of the element.

EX: CO2

EX: CO

carbon

carbon

Naming Covalents

2)Name the second element, end in –ide, and put a prefix at the beginning even if there is only one.

EX: CO

EX: CO

carbon

carbon

oxide

oxide

2

di“understood one”

1mon

Naming Covalents

EX:

N O2 5

nitrogen oxideDi pent

Name These:

•SO2

•NO

•Cl2S

•BCl3

•P2S7

Sulfur dioxide

Nitrogen monoxide

Dichlorine monosulfide

Boron trichloride

Diphosphorus pentasulfide

Writing Molecular Formulas

1) Write the symbol for the 1st element and use the prefix to determine the subscript.

EX:nitrogenDi sulfidepentanitrogen sulfideDi

N2

sulfidepenta

Writing Molecular Formulas

2) Write the symbol for the 2nd element and use the prefix to determine the subscript.

EX:nitrogenDi sulfidepentanitrogen sulfideDi

N2

sulfidepenta

S5

Name These:

•Carbon tetrachloride•Dinitrogen heptoxide•Carbon monoxide•Dichlorine monoxide•Trisilicon decaoxide

SO2

N2O7

COCl2O

Si3O10