CHAPTER 5.1

1. CHAPTER 5.1 IONIC COMPOUNDS

2. IONIC COMPOUNDS • Charged ions with neutral cpd. • Water soluble • Metal with non metal • Brittle • Electric conductor • Tightly bound repeating patterns in crystals • Cation: + charged ion • Anion: - charged ion

3. Types of Ionic Compounds • I. Binary Ionic Compounds • only contains 2 elements • (can have more than one ion of each element) • - Bi – Latin for “2” • Ex: NaCl sodium chloride • - charges cancel each other • - compound is neutral • - do not write charges of ions in formula • - 1:1 ratio of each element

4. Binary Ionic Compounds • ex: CaFl2 calcium flouride • (1:2 ratio) • AlCl3 aluminum chloride • (1:3 ratio) • K2Spotassium sulfide • (2:1 ratio)

5. Naming Binary Ionic Compounds • Rules • 1. Write name of metal ( + cation) • 2. Write name of non metal (- anion) • 3. Change non metal name to end in “ide” • (number of each element does not change name)

6. Name the following binary compounds: • Mg2O3 • magnesium oxide • KCl • potassium chloride • Na2S • sodium sulfide • LiI • lithium iodide • TiBr • titanium bromide

7. Writing Formulas • Rules • If more than one ion of an element is present, the subscript tells how many • Write subscript below and to the right of element • (sub-below) • Write the formula unit (simplest ratio of elements) • Ex: FORMULA UNITREPEATING PATTERN • CaF2 Ca2F4 Ca3F6 • NaCl Na2Cl2 Na6Cl6 • Ga2S3 Ga4S6 Ga8S12

8. Write the formula units for the following: • Rb2F2 • RbF • Mg3Cl9 • MgCl3 • Al6O18 • AlO3 • C12H24O12 • CH2O • H4S2O8 • H2SO4

9. Writing Binary Ionic Formulas • Rules • Write the symbol for the metal then the non-metal • Determine the oxidation number of each element • (use periodic table) • oxidation number: charge on ion (superscript) • - tells number of electrons atom gains or loses

10. Oxidation Numbers • Metals: • - always have + charge (lose negative electrons) • - charge equals group # on periodic tbl. • (remove 1 in front of group 13)

11. Oxidation Numbers • Non metals: • - always have – charge (gain negative electrons) • - charge equals 8 minus group # (remove 1 in front of groups 15, 16, 17, 18)

12. 3. Rewrite formula so compound is neutral • (positive and negative charges must be equal) • ex: Mg2+ Br – • Are the charges equal? • In order for the compound to be neutral we must have equal positive and negative charges. • CRISS-CROSS RULE • 1. take number of metal’s superscript (number above element) • 2. move this number to bottom right of non-metal symbol • (now a subscript, loses charge) • 3. do the same for the non-metal

13. Criss Cross Rule • Ex: Mg Br • Mg 2+Br - • Mg1 Br2 • Final Formula (do not write charges on subscripts) • Mg Br2 charges are equal, compound is neutral • Mg has 2+ charges x one atom = 2+ charges • Br has 1- charge x two atoms = 2- charges

15. Polyatomic Compounds • compound that contains more than two elements • Polyatomic Ion: Ion that has two or more different elements in a grouped unit which carries a charge • a. whole ion is charged, not last element listed • b. treated same as single element’s (monoatomic) ion • ex: ammonium cyanide • NH4+CN- • polyatomic polyatomic • ion ion

16. can contain: • 1. one (+) metal bonded to (–) polyatomic ion • Na+OH- • metal nonmetal • 2. (+) polyatomic ion bonded to one (-) non metal ion • NH4+I-polyatomic nonmetal • ion • 3. (+) polyatomic ion bonded to a (-) polyatomic ion • NH4+NO3- • polyatomic polyatomic

18. Naming Polyatomic Compounds • Rules • name + ion first, followed by name of – polyatomic ion • do not change ending of – polyatomic ion • ex: CaCO3 • calcium carbonate

19. (use reference sheet) LiNO2 lithium nitrate MgSO4 magnesium sulfate CaPO4 calcium phosphate NaOH sodium hydroxide * H3OCl hydronium chloride * Remember to change non metal’s name to “ide” NaCN sodium cyanide AlSO3 aluminum sulfite KNO3 potassium nitrate MgCr2O7 magnesium dichromate * NH4I ammonium iodide Name the following polyatomic compounds:

20. Writing Polyatomic Formulas • Rules • Use criss-cross method • 2. Put parenthesis around polyatomic ion • 3. Criss-cross superscript to bottom right of parenthesis around polyatomic ion

21. Practice Problems

22. Transition Element Compounds • (groups 3-12) • a. form + ions like metals • b. can have more than one type of + ion • (have more than 1 oxidation number) • c. named by using name of element followed by • oxidation number as Roman numeral in parenthesis • ex: Cu(I)Cl copper I chloride • Cu(II)Cl copper II chloride

26. Hydrates • ionic compound that contains H2O molecules weakly bound in its crystals • - when hydrates lose their water, the end compound has different properties than the original hydrate • ex: popcorn kernel popped corn yellow, hard white, soft • cobalt chloridecobalt chloride • (anhydrous) (hydrate) • cement gelcement hardened

27. Hygroscopic substances: • Ionic compounds that easily become hydrates (absorb H2O) • The thorny devil features hygroscopic grooves between the spines of their skin to capture water in their desert habitat. • Deliquescent substances: • Substance that absorbs so much water it becomes liquid • salts • Dessicants: • Absorb water vapor and keeps surrounding substance dry • silica gel packs inside electronics • Anhydrous compound: • Hydrate with all water removed • anhydrous sodium sulfate

28. Naming Hydrates • Rules • Write the name of the compound • Write the prefix of the number of water molecules • Add the word “hydrate” to the prefix • ex: Ba(NO3)2 .4H2O • barium nitrite tetrahydrate

29. Prefixes for Naming Compounds

30. Name the following hydrates:

31. Writing Hydrate Formulas • Rules • Write the formula for the compound (must be neutralized) • Place a dot after formula • Write the number of water molecules • ex: copper sulfate dihydrate • CuSO4.2 H2O • sodium carbonatepentahydrate • Na2CO3.5H2O

32. Write the formulas for the following hydrates:

33. Study for the test !