1. Chemical Formulas Review Transition Metals and Polyatomic Ions

2. Transition Metals Recall: – Transition metals (with few exceptions) form cation with more than one possible charge Ex: Fe  Fe 2+, Fe 3+ ; Pb  Pb 2+, Pb 4+ – In ionic compounds, these charge are also their oxidation numbers – We can write balanced chemical formulas by using the cross-over method

3. Example A compound containing an Sn 2+ ion and a Cl - ion: 1. Sn 2+ Cl - 2. Sn 2+ 1 Cl - 2 3. SnCl 2 Practice! Write formulas that contain the following: Pb 4+ ion and O 2- ion Cr 3+ ion and I - ion

4. Transition Metals, cont. Sometimes you will see a Roman numeral in parenthesis written after the name of the metal – This represents the charge/ oxidation number of the ion – Ex: Copper(II) ion  Cu 2+ ion

5. Naming Compounds with Transition Metals Stock System – Name the metal first Include the charge of the ion as a Roman numeral in parenthesis immediately after – Name the nonmetal second Ex: CuCl 2  copper(II) chloride PbBr 4  lead(IV) bromide Practice: HgS  Fe 2 O 3  CoF 3 

6. Polyatomic ions Ions that contain more than one atom Oxyanions- contain oxygen + another nonmetal Negatively charged/ negative oxidation numbers – Only exception is ammonium (NH 4 + )

7. +1-2-3 Ammonium NH 4 + acetate C 2 H 3 O 2 − CH 3 COOH − Carbonate CO 3 2- Phosphate PO 4 3- Bicarbonate HCO 3 - Chromate CrO 4 2- Cyanide CN - Dichromate Cr 2 O 7 2- Hydroxide OH - Peroxide O 2 2- Nitrate NO 3 - Sulfate SO 4 2- Nitrite NO 2 - Sulfite SO 3 2- Perchlorate ClO 4 - Permanganate MnO 4 - Know These Polyatomic Ions!

8. Writing Chemical Formulas with Polyatomic Ions Use the crossover technique Do NOT change the subscripts of the ions!!! If the compound contains more than one of that ion, put the ion in parenthesis, and place the subscript outside the parenthesis

9. Example A compound containing Ca 2+ ion and NO 3 - polyatomic ion 1. Ca 2+ NO 3 - 2. Ca 2+ 1 (NO 3 ) - 2 3. Ca(NO 3 ) 2 Practice! Write formulas containing the following: Na + ion and CO 3 2- ion Mg 2+ ion and OH - ion

10. Naming Compounds Containing Polyatomic Ions Name metal first (watch out for transition metals!) Name polyatomic ion second – Only exception is with ammonium- it is always named first

11. Homework: Due 11-6-2012 Write balanced chemical formulas that contain the following: 1. Cr 3+ ion and NO 3 - ion 2. Li + and CrO 4 2- ion 3. Sn 4+ ion and N 3- ion 4. NH 4 + ion and PO 4 3- ion 5. Al 3+ and CO 3 2- ion Name the following compounds: 1.PbMnO 4 2.NaNO 2 3.(NH 4 ) 3 PO 4 4.MgSO 4 5.Na 2 O 2