1. Chem Lab Methods

2. Chemical Symbols

3.  Use the chemical symbol for each element  Usually, the element abbreviations come from the word (He for Helium or Ti for Titanium)  Some elements have just one letter, such as H for Hydrogen or N for Nitrogen

4.  Most elements have two letters  Always capitalize the first letter and use lower case on the second one.  Example: Cobalt is Co  If you used two capitals (CO), it would be mistaken for Carbon Monoxide which has one Carbon (C) and one Oxygen (O)

5. The subscript number specifies how many atoms of that element you have  N 2 is a nitrogen molecule with two atoms  C 2 H 4 has two carbons and four hydrogens  CO 2 contains one carbon and two oxygens  If no number is listed, it means there is only one

6.  C 2 H 3 Cl what elements and how many of each?

7.  C 2 H 3 Cl what elements and how many of each?

8.  H 2 SiCl 2 what elements and how many of each?

9.  H 2 SiCl 2 what elements and how many of each?

10.  CH 4 what elements and how many of each?

11.  CH 4 => methane what elements and how many of each?

12.  When there are large numbers in front, that tells you how many molecules there are.  For example 3CH 4 =

13.  When there are large numbers in front, that tells you how many molecules there are.  For example 3CH 4 = 3 methane molecules  12NaOH = ?

14.  When there are large numbers in front, that tells you how many molecules there are.  For example 3CH 4 = 3 methane molecules  12NaOH = 12 different Sodium Hydroxide units

15.  Counting Atoms

16.  Nomenclature:  Choosing of names for things  Naming procedure  Ionic Compound:  Atoms held together by ionic bonds  Binary Compound:  Chemical compound made of atoms from two different elements

17.  Metal element name first  Then the non-metal element name, but the ending is changed to -ide Example: CaCl 2 would be called calcium chloride Example: Ag 2 O would be called… silver oxide

18.  Naming Binary Compounds

19. Example: Compound name - Magnesium chloride …What is the formula?

20. Magnesium Chloride = Mg +2 Cl -1 What charge ion would each atom form? How many of each to make a neutral compound ?

21.  Magnesium Chloride: Mg +2 and Cl -1  The charge of the final compound must be neutral. (The charges must balance) ▪ Need TWO Cl -1 ions to balance one Mg +2 ion ▪ (2 x -1) = (1 x +2) = 2 minus balances 2 plus  (Criss Cross!) Mg 1 Cl 2  MgCl 2

22. Magnesium Chloride = 1 Mg +2 + 2 Cl -1 => MgCl 2 Mg +2 Cl -1

23. Example: Compound name Lithium sulfide …What is the formula?

24. Lithium Sulfide= Li +1 S -2 What charge ion would each atom form? How many of each to make a neutral compound ?

25.  Magnesium Chloride: Li +1 and S -2  The charge of the final compound must be neutral. (The charges must balance) ▪ Need TWO Li +1 ions to balance one S -2 ion ▪ (2 x +1) = (1 x -2) = 2 minus balances 2 plus  (Criss Cross!) Li 2 S 1  Li 2 S

26. Lithium sulfide = 2 Li +1 + 1 S -2 => Li 2 S Li +1 S -2

27. Example: Compound name Aluminum oxide …What is the formula?

28. Aluminum Oxide= Al +3 O -2 What charge ion would each atom form? How many of each to make a neutral compound ?

29.  Aluminum Oxide: Al +3 and O -2  The charge of the final compound must be neutral. (The charges must balance) ▪ Need TWO Al +3 ions to balance THREE O -2 ions ▪ (2 x +3) = (3 x -2) = 6 minus balances 6 plus  (Criss Cross!) Al 2 O 3  Al 2 O 3

30. Boron Oxide = 2 Al +3 + 3 O -2 => Al 2 O 3 B +3 O -2

31. SUMMARY of approach:  Determine what charge ion would form from each element  Decide how many of each charge are needed to have a balanced (neutral) formula OR do “Criss Cross”  Write formula  Subscripts state how many of each ion are needed

32. Ionic compound formula describes:  One “unit” of the chemical compound  Thus, it is called a “formula unit”  Important definition  Example: 3 CaCl 2  Three “formula units” of calcium chloride

33.  Writing (Balanced) Chemical Formulas

34. Two more details:  Complex ions: contain more than one element  Transition metals: ionic charges can vary

35.  Examples:  Acetate is (C 2 H 3 O 2 ) -1 ▪ Whole group has -1 ionic charge  Carbonate is (CO 3 ) -2 ▪ Whole group has -2 ionic charge  The ENTIRE group has one ionic charge  Acts like a single-atom ion of the same charge  List of common complex ions on the back of your periodic table

36.  All but ONE of the common complex ions are negative  Phosphate is (PO 3 ) -3 ▪ Whole group has -3 ionic charge  Chlorate is (ClO 3 ) -1 ▪ Whole group has -1 ionic charge  THE positive complex ion (worth memorizing) is:  Ammonium (NH 4 ) +1

37.  Magnesium Phosphate: Mg +2 and (PO 4 ) -3  The charge of the final compound must be neutral. (The charges must balance) ▪ Need THREE Mg +2 ions to balance TWO (PO 4 ) -3 ions ▪ (3 x +2) = (2 x -3) = 6 minus balances 6 plus  (Criss Cross!) Mg 3 (PO 4 ) 2  Mg 3 (PO 4 ) 2

38.  Ionic charge can vary  How do you know?  Listed on Periodic Table  “Clue” in name

39. ElementCationNamePronounced CopperCu + Cu 2+ IronFe 2+ Fe 3+ Lead Pb 2+ Pb 4+ Tin Sn 2+ Sn 4+

40. ElementCationNamePronounced CopperCu + Copper (I)copper one Cu 2+ IronFe 2+ Fe 3+ Lead Pb 2+ Pb 4+ Tin Sn 2+ Sn 4+

41. ElementCationNamePronounced CopperCu + Copper (I)copper one Cu 2+ Copper (II)copper two IronFe 2+ Fe 3+ Lead Pb 2+ Pb 4+ Tin Sn 2+ Sn 4+

42. ElementCationNamePronounced CopperCu + Copper (I)copper one Cu 2+ Copper (II)copper two IronFe 2+ Iron (II)iron two Fe 3+ Iron (III)iron three Lead Pb 2+ Pb 4+ Tin Sn 2+ Sn 4+

43. ElementCationNamePronounced CopperCu + Copper (I)copper one Cu 2+ Copper (II)copper two IronFe 2+ Iron (II)iron two Fe 3+ Iron (III)iron three Lead Pb 2+ Lead (II)lead two Pb 4+ Lead (IV)lead four Tin Sn 2+ Tin (II)tin two Sn 4+ Tin (IV)tin four

44. Write the chemical formula for Iron (II) Oxide  Step One: Determine the charges  Iron (II) = Fe 2+ and Oxide = O 2-  Step Two: See how to balance the charges  Step Three: Find the combination that balances  Iron (II) Oxide = FeO

45. Write the chemical formula for Lead (II) Nitride  Step One: Determine the charges  Lead (II) = Pb +2 and Nitride = N -3  Step Two: See how to balance the charges  Step Three: Find the combination that balances  Lead (II) Nitride = Pb 3 N 2

46.  Do not use Roman Numerals for groups 1 or 2 as they are always (+1) and (+2) accordingly. K = +1 and Ca = +2 +1 +2

47.  Do not use Roman numerals for transition metals that always form the same charge ion.  Ag = +1 and Zn = +2 and Cd = +2

48.  Ionic Compound Formula Writing (all types)