1. Review of Grades 9 - 11 Science

2. Significant Digits 1.Begin counting at the first non-zero digit a)if there is a decimal, count to the last digit Ex: 23.50 mol (4 s.d.) 0.068 mL (2 s.d.) b) if there is no decimal, count to the last non- zero digit Ex: 750 g (2 s.d.)

3. Significant Digits 2.Numbers with an infinite number of significant digits: a)Counting Numbers (eg 12 eggs [not 11 or 13] - repeating decimal of 0) b)Numbers as definitions of equalities (eg 1 L = 1000 mL) c)Coefficients in a chemical equation

4. Significant Digits 3.Mathematical Operations a) Multiplication & Division Round off the answer to the least number of significant digits. Ex: 12.8 cm x 5.4 cm = 69 cm 2 (2 s.d)

5. Significant Digits 3.Mathematical Operations b) Addition & Subtraction Round off the answer to the least number of decimal places. Ex: 355.84 g – 73.1 g = 282.74 g = 282.7 g

6. Accuracy in Measurement Use percentage difference: % Difference =  experimental value – predicted value| x 100% predicted value

7. Significant Digits Rounding Off Performed ONLY at the end of a solution If discarded digit is a)0 - 4 the last digit retained is left the same b)5 - 9 the last digit retained is increased by one

8. Nomenclature Common ions - page 801 Common multivalent metal ions - page 807 Review: (See next slide)

9. Nomenclature - What System to use? SYSTEM FIRSTIUPACCOMMONEXAMPLE ELEMENTSTOCKNONEPREFIX"IC/OUS" metal (1 oxid #) X potassium chloride K+(KCl) Mg 2+ metal (>1 oxid #) X copper(I) sulfide X cuprous sulfide Cu+(Cu 2 S), Cu 2+ Fe 2+, Fe 3+ metalloid (1 oxid #) XX silicon tetrahydride Si 4+ (SiH 4 ) metalloid (>1 oxid #) X arsenic (III) fluoride X arsenic trifluoride As 3+ (AsF 3 ) As 5+ nonmetalX nitrogen (II) oxide X nitrogen monoxide N 2+ (NO) N 3+ N 4+,N 5+

10. Nomenclature Binary Compounds use suffix "ide" (two exceptions for polyatomic "ide" - hydroxide, cyanide) Ions with more than 1 oxidation number "ic" higher oxidation number"ous" lower oxidation number - Latin names: ferrum, cuprum, plumbum, aurum, stannum

11. Nomenclature Polyatomic Compounds "ate", "ite", look on the table below the periodic table

12. Nomenclature - Acids Binary - use prefix "hydro" (only use of "hydro" in chemistry nomenclature) Polyatomic -"ate" ion forms an "ic acid" Ex: nitrate NO 3 1- and nitric acid HNO 3(aq) - "ite" ion forms an "ous acid" Ex: nitrite NO 2 1- and nitrous acid HNO 2(aq)

13. Nomenclature - Acids Oxy-acid prefixes and suffixes Hypo... ite - 2 less "O" than "ate"... ite - 1 less "O" than "ate" per... ate - 1 more "O" than 'ate"

14. Nomenclature Hydrates: water after a compound Ex: CuSO 4. 5H 2 Ocopper(II) sulfate pentahydrate Diatomic Ions: Hg 2 2+ O 2 2- Diatomic Elements H 2 O 2 F 2 Br 2 I 2 N 2 Cl 2

15. Humour Break! Little Willie was a chemist. Little Willie is no more. For what he thought was H 2 O Was H 2 SO 4 Teacher: What is the formula for water? Student: H, I, J, K, L, M, N, O Teacher: That's not what I taught you. Student: But you said the formula for water was...H to O.

16. Ionic Equations Use Solubility rules on p.487, 801 & 808 or SCH4U data sheets provided

17. Ionic Equations - Example For the reaction involving lead (II) nitrate solution and potassium iodide solution a precipitate and a salt solution are produced. a) Write the balanced chemical equation for this chemical reaction. b) Write the balanced ionic equation for this chemical reaction. (TIE) c) Write the balanced net ionic equation for this chemical reaction. (NIE)

18. Ionic Equations - Example a)Pb(NO 3 ) 2(aq) + 2KI (aq)  PbI 2(s) + 2KNO 3(aq) b) (TIE) Pb 2+ (aq) +2NO 3 1- (aq) +2K 1+ (aq) +2I 1- (aq)  PbI 2(s) +2K 1+ (aq) + 2NO 3 1- (aq) c) (NIE) Pb 2+ (aq)) +2I 1- (aq)  PbI 2(s)

19. Chemical Bonding The difference in electronegativity (ΔEN) can be used to describe the chemical bond as ionic (  EN > 1.7) polar covalent (  EN 0.5 - 1.7) nonpolar covalent (  EN < 0.5) In a polar molecule the bond dipoles do NOT cancel. Ex: compare H 2 O, CO 2

20. Chemical Quantities Recall:n number of moles mmass(g) Mmolar mass (g/mol) Nnumber of entities N A Avogadro’s number For solutions Cmolar concentration (mol/L)

21. Summary Text Reference: pages 778-780, 806 – 812, 814-815

22. Humour Break! Q: Why do chemists like nitrates so much? A: They're cheaper than day rates. Q: Why are chemists great for solving problems? A: They have all the solutions.