1. Representing Chemical Compounds Naming Compounds and Writing Chemical Formulas

2. Chemical Formula Shows the kinds and numbers of atoms in a substance. If only one atom of the element in a compound, you only write the element’s symbol. (Ex: Lithium fluoride  LiF) If the molecules of the element each have more than one atom, a number is used as a subscript. (Ex: Lithium oxide  Li 2 O).

3. Molecular Formulas Chemical formula for a molecular compound is called a molecular formula. Shows the kinds and numbers of atoms present in a molecule of a compound. Examples: CO, CO 2 Tells nothing about the structure of the molecule --- doesn’t show arrangement of the various atoms.

4. Formula Units Chemical formulas represent ionic compounds. Formula units – lowest whole-number ratio of ions in the compound.

5. Ionic Charges For most of the Group A elements, the Periodic Table can tell what kind of ion they will form from their location. Elements in the same group have similar properties. Including the charge when they are ions.

6. +2 +1 +3 -3-2

7. Warm-Up 1.What is another name for the elements in Group 18 on the Periodic Table? 2.What is another name for the elements in Group 17 on the Periodic Table? 3.What is the oxidation number for ions in Group 1 on the Periodic Table? 4.What is the name of this compound: NaCl

8. Naming Cations Cation- if the charge is always the same (Group A) just write the name of the metal. Transition metals can have more than one type of charge. Indicate the charge with roman numerals in parentheses.

9. Name These Na +1 Ca +1 Al +3 Fe +3 Fe +2 Pb +3 Li +1

10. Write Formulas for these Potassium ion Magnesium ion Copper (II) ion Chromium (VI) ion Barium ion Mercury (II) ion

11. Naming Anions Anions are always the same. l Change the element ending to – ide. l F-1 Fluorine l F-1 Fluoride

12. Name These N-3 Br-1 O-2 Ga+3

13. Write These Sulfide ion iodide ion phosphide ion Strontium ion

14. Polyatomic Ions Groups of atoms that stay together and have a charge.

15. Ions in Ionic Compounds

16. Naming Binary Ionic Compounds Binary Compounds - 2 elements. Ionic - a cation and an anion. To write the names just name the two ions. Easy with Representative elements. Group A NaCl = Na+ Cl- = sodium chloride MgBr 2 = Mg+2 Br- = magnesium bromide

17. The problem comes with the transition metals. Need to figure out their charges. The compound must be neutral. same number of + and – charges. Use the anion to determine the charge on the positive ion.

18. Naming Binary Ionic Compounds Write the name of CuO Need the charge of Cu O is -2; copper must be +2 CuO – Copper (II) oxide Name CoCl 3 Cl is -1 and there are three of them = -3 Co must be +3 CoCl 3 – Cobalt (III) chloride

19. Naming Binary Ionic Compounds Write the name of Cu 2 S. Since S is -2, the Cu 2 must be +2, so each one is +1. Cu 2 S – Copper (I) sulfide Name Fe 2 O 3 Each O is -2 3 x -2 = -6 3 Fe must = +6, so each is +2. Fe 2 O 3 – Iron (III) oxide

20. Naming Binary Ionic Compounds Write the names of the following KCl Na 3 N CrN Sc 3 P 2 PbO PbO 2 Na 2 Se

21. Naming Tertiary Ionic Compounds 1.Write the name of the element represented by the first symbol in the compound. 2.Write the name of the polyatomic ion without changing the ending. 3.Follow all other rules for naming such as the rule for naming transition elements.

22. Naming Tertiary Ionic Compounds Example: Fe(NO 3 ) 2 NO 3 is the polyatomic ion nitrate, which is -1 There are 2 NO 3 ’s, so the total charge on nitrate is -2 Therefore Fe must be +2 Fe(NO 3 ) 2  iron (II) nitrate

23. Writing Formulas The charges have to add up to zero. Get charges on each element. Name the Cations from the Periodic Table. Anions end in -ide. Balance the charges by adding subscripts. Put polyatomic ions in parentheses.

24. Writing Formulas Write the formula for calcium chloride. Calcium is Ca +2 Chloride is Cl -1 Ca +2 Cl -1 would have a +1 charge. Need another Cl -1 Ca +2 Cl 2-  CaCl 2

25. Write the formulas for these Lithium sulfide tin (II) oxide tin (IV) oxide Magnesium fluoride Copper (II) sulfate Iron (III) phosphide Iron (III) sulfide

26. Warm-Up: Write the formulas for these compounds Ammonium chloride Ammonium sulfide Barium nitrate

27. Things to look for If cations have (), the number is their charge. If anions end in -ide they are probably off the periodic table (Monoatomic) If anion ends in -ate or -ite it is polyatomic

28. Molecular Compounds Writing names and Formulas

29. Molecular compounds made of just nonmetals smallest piece is a molecule can’t be held together because of opposite charges. can’t use charges to figure out how many of each atom

30. Easier Ionic compounds use charges to determine how many of each. –H–Have to figure out charges. –H–Have to figure out numbers. Molecular compounds name tells you the number of atoms. Uses prefixes to tell you the number

31. Prefixes 1 mono- 2 di- 3 tri- 4 tetra- 5 penta- 6 hexa- 7 hepta- 8 octa-

32. Prefixes 9 nona- 10 deca- To write the name write two words Prefix name Prefix name -ide One exception is we don’t write mono- if there is only one of the first element. No double vowels when writing names (oa oo)

33. Name These N 2 O NO 2 Cl 2 O 7 CBr 4 CO 2 BaCl 2

34. Write formulas for these diphosphorus pentoxide diphosphorus tetraiodide sulfur hexaflouride dinitrogen trioxide carbon tetrahydride phosphorus trifluoride

35. Acids Writing names and Formulas

36. Acids Compounds that give off hydrogen ions when dissolved in water. Must have H in them. will always be some H next to an anion. The anion determines the name.

37. Naming acids If the anion attached to hydrogen is ends in - ide, put the prefix hydro- and change -ide to - ic acid HCl - hydrogen ion and chloride ion hydrochloric acid H2S hydrogen ion and sulfide ion hydrosulfuric acid

38. Naming Acids If the anion has oxygen in it, it ends in -ate or -ite If it ends in -ate, drop the Hydrogen and change the suffix -ate to -ic acid HNO3 - Hydrogen and nitrate ions  Nitric acid If the anion ends in –ite, change the suffix -ite to -ous acid HNO2 Hydrogen and nitrite ions Nitrous acid

39. Name these HF H 3 P H 2 SO4 H 2 SO 3 HCN H 2 CrO 4

40. Writing Formulas Hydrogen will always be first Name will tell you the anion Make the charges cancel out. Starts with hydro, no oxygen, -ide No hydro, -ate comes from -ic, -ite comes from -ous

41. Write formulas for these hydroiodic acid acetic acid carbonic acid phosphorous acid hydrobromic acid

42. Exit Slip Explain the rules for naming acids in your own words. What is the name of the compound HCl? What is the chemical formula for the compound sulfuric acid?