2. Unit 7.1 Naming Molecular Compounds Teacher: Dr. Van Der Sluys

3. Objectives Naming molecular compounds –Using prefixes –Stock naming system

4. Prefixes A prefix is a morpheme (portion of a word) that comes at the beginning of the word and has a specific meaning Mono-onePenta-five Di-twoHexa-six Tri-threeHepta-seven Tetra-fourOcta-eight

5. Naming Molecular Compounds with Prefixes 1.Use a prefix to indicate how many atoms there are of the first element in the formula, except if there is only one atom of the first element, then do not use the prefix mono-. 2.After the prefix, use the name of the first element in the formula. 3.Use a prefix to indicate the number of atoms for the second element in the formula. 4.Use the root of the second elements name and the suffix -ide.

6. Examples N 2 Odinitrogen monoxide NOnitrogen monoxide NO 2 nitrogen dioxide CO 2 carbon dioxide COcarbon monoxide

7. More Examples CF 4 SO 2 SF 6 Dichlorine heptaoxide Hydrogen chloride Phosphorus trichloride

8. Exceptions H 2 Owater NH 3 ammonia Organic compounds - compounds containing carbon bonded to hydrogen have their own unique naming system –CH 4 methane –C 2 H 6 ethane –C 3 H 8 propane

9. The Stock Naming System The International Union of Pure and Applied Chemists (IUPAC) have developed a naming system based on the oxidation numbers of the first element in the formula. 1.Name the first element. 2.Use a Roman numeral to indicate the oxidation number, by reversing the criss-cross and determining the charge as if it were an ionic compound. 3.Use the root of the second elements name and end with the suffix -ide.

10. Rationale In compounds that contain polar covalent bonds, electrons are displaced towards the more electronegative atom. This results in partial positive negative charges. The stock naming system assumes that the bonding is ionic rather than covalent. O=C=O Carbon dioxide.. [:O:] 2- [C] 4+ [:O:] 2-.. Carbon (IV) oxide

11. Example CF 4 C 4+ and F - Carbon (IV) fluoride N 2 ON + and O 2- Nitrogen (I) oxide CO 2 C 4+ and O 2- carbon (IV) oxide SF 6 S 6+ and F - sulfur (VI) fluoride

12. Examples CO NO 2 Phosphorus (V) oxide Chlorine (VII) oxide

13. Summary Prefixes are used to indicate the number of each element in the formula Stock naming system uses roman numerals to indicate the charge of the first element as determine from the criss-cross system.