1. J OURNAL #28 Correct your quiz and copy the questions into your journal (for journal credit) You must copy the correct answers on another separate piece of paper and attach to the quiz for extra points!

2. T ODAY, WE WILL NAME BINARY MOLECULAR COMPOUNDS

3. B INARY M OLECULAR C OMPOUNDS Unlike ionic compounds, molecular compounds are composed of individual covalently bonded units, or molecules. Chemists use two nomenclature systems to name binary molecules. Stock System- requires an understanding of oxidation numbers. The old system- based on prefixes Examples: CCl 4 is carbon tetra floride. CO is carbon mon oxide CO 2 is carbon dio xide

4. R ULES FOR THE P REFIX S YSTEM The element that has the smaller group number is usually given first. If both elements are in the same group, the element whose period is greater is given first. The element is given a prefix only if it contributes more than one atom. The second element is named by combining: A prefix indicates the number of atoms Root name -ide at the end indicates only 2 elements The O or A at the end of a prefix is usually dropped when the work following the prefix is a vowel. Example: monoxide instead of mono-oxide

5. N UMERICAL P REFIXES : NumberPrefix 1Mono- 2Di- 3Tri- 4Tetra- 5Penta- 6Hexa- 7Hepta- 8Octa- 9Nona- 10Deca-

6. L ET ’ S P RACTICE : Binary compounds of Nitrogen and Oxygen 1. N 2 0 2. NO 3. NO 2 4. N 2 O 3 5. N 2 O 4 6. N 2 O 3

7. L ET ’ S P RACTICE : Give the name for As 2 O 5 Write the formula for oxygen difluoride. Name the following binary molecular compounds: SO 3 ICl 3 PBr 5