1. Naming Chemical Compounds 3221.3.1, 3221.3.2

2. Objectives TLW write chemical formulas of ionic and molecular compounds. TLW name chemical compounds using the correct system. TLW use polyatomic ions.

3. Significance of a chemical formula Recall that a chemical formula indicates the relative number of atoms of each kind in a chemical formula C 8 H 18 Hydrocarbon: molecular compounds composed only of hydrogen and carbon

4. Two Types of Chemical Compounds 1.ionic: bond between anions (-) and cations (+) (electrons are donated) nonmetal—metal 2.molecular: (covalently bonded—electrons are shared) nonmetal—nonmetal 3.Metallic: electron “sea” allowing few electrons to be shared among many atoms metal—metal

5. Monatomic Ions Ions formed from a single atom Groups 1 and 2 metals lose electrons to form cations Groups 15, 16, and 17 gain electrons to form anions Naming cations is very simple: identified by the element’s name K + potassium cation Mg 2+ magnesium cation Naming anions: drop the ending to the element’s name and add –ium O 2- oxide Cl - chloride

6. Transition metals have variable charges!!!

7. Stock System When naming ionic compounds and an element has multiple possible charges, the charge is given in roman numerals in () after the name of the metal Fe2+iron (II) Fe3+iron (III) Naming a binary ionic compound according to the stock system illustrated below. CuCl 2

8. Binary Ionic Compounds Binary compounds: compounds composed of two elements The total number of positives and negatives must be equal, resulting in an overall neutral charge Na ClMg Br 2

9. Writing chemical formulas for binary ionic compounds “crossing over”: a method of balancing charges between ions in an ionic compound 1.Write the symbols for the ions side by side. Write the cation (+) first! 2. Cross over the charges by using the absolute value of each ion’s charge as the subscript for the other ion 3. Check to make sure the numbers are in the smallest possible ratio!

10. Naming Binary Ionic Compounds -The nomenclature, or naming system, of binary ionic compounds involves combining the names of the compound’s positive and negative ions -the cation is ALWAYS written first!! -charges are ONLY given as part of the name if multiple charges are possible

11. Practice Potassium and iodine Magnesium and chlorine Sodium and sulfur Sulfur and aluminum Nitrogen and aluminum

12. More practice AgCl ZnO CaBr 2 SrF 2 BaO CaCl 2

13. Compounds containing polyatomic ions Most polyatomic ions are oxyanions—polyatomic ions that contain oxygen Some elements can combine with oxygen to form more than one type of oxyanion NO 2 - nitrite (fewer O atoms)NO 3 - nitrate SO 3 2- sulfite (fewer O atoms)SO 4 2- sulfate

14. Sometimes an atom can form more than 2 oxyanions… HypochloriteClO - fewer O than –ite ion ChloriteClO 2 - ChlorateClO 3 - PerchlorateClO 4 - one more O than –ate ion

15. Practice Sodium iodide Calcium chloride Potassium sulfide Lithium nitrate Copper (II) sulfate Sodium carbonate Calcium nitrite Potassium perchlorate

16. Practice AgO Ca(OH) 2 KClO 3 NH 4 OH Fe 2 (CrO 4 ) 3 KClO

17. Naming Binary Molecular Compounds Unlike ionic compounds, molecular compounds are composed of individually bonded units, or molecules Two Systems: 1.Prefixes (“Old system”) 2.Stock system (uses oxidation numbers) NONMETAL—NONMETAL

18. Examples CCl 4 carbon tetrachloride (tetra: prefix for 4) CO2carbon dioxide (di: prefix for 2) P 4 O 10 tetraphosphorus decoxide (deca: prefix for 10)

19. Prefixes Number Prefix 1 mono- 2 di- 3 tri- 4 tetra- 5 penta- 6 hexa- 7 hepta- 8 octa- 9 nona- 10 deca-

20. Binary Compounds of N and O N 2 Odinitrogen monoxide NOnitrogen monoxide NO 2 nitrogen dioxide N 2 O 3 dinitrogen trioxide N 2 O 4 dinitrogen tetraoxide N 2 O 5 dinitrogen pentoxide No prefix is used for the first atom if it is a single atom

21. Practice SO 3 ICl 3 PBr 5 Carbon tetraiodide Phosphorus trichloride Dinitrogen trioxide