Carbon and oxygen combine to form

carbon monoxide (CO) and carbon dioxide (CO2),

but these two invisible gases are very different.

A prefix tells how many atoms of each element are present in one molecule.

Prefix Number Prefix Numbermono- 1 hexa- 6

di- 2 hepta- 7tri- 3 octa- 8

tetra- 4 nona- 9penta- 5 deca- 10

carbon monoxide (CO) carbon dioxide (CO2)

Molecular Naming Rules:

1)Name elements in formula order.

2)Prefixes show the number of each atom.

3)Suffix of last element is –ide.

4)No prefix mono- for first element.

CCl4

N2O nitrogen oxygendi mon ide

carbontetrachloride

sulfurtrioxide

SO3 H2Odihydrogenmonoxide

1. Which of the following compounds is named INCORRECTLY?

A. CS2 carbon disulfide

B. BCl3 boron trichloride

C. IF7 iodine heptafluoride

D. PCl5 phosphorus hexachloride

Quick Quiz!

2. Which of the following molecular compounds is named INCORRECTLY?

A. PCl3 phosphorus trichloride

B. C2O5 dicarbon pentoxide

C. CF4 carbon tetrafluoride

D. H3P hydrogen monophosphide

Quick Quiz.

3. The correct formula forhexaphosphorus trisulfide is

A. P7S3

B. S3P6

C. P6S3

D. S3P7

Quick Quiz.

A prefix tells how many atoms of each element are present in one molecule.

Prefix Number Prefix Numbermono- 1 hexa- 6

di- 2 hepta- 7tri- 3 octa- 8

tetra- 4 nona- 9penta- 5 deca- 10