Chapter 8 Ionic Compounds

1. Chapter 8 Ionic Compounds Why do atoms form bonds? • Stability • Like the noble gases, every element wants to be inert • Not a nerd I. Forming Chemical Bonds – How do Compounds Form?

2. I. Why do atoms form bonds? Chemical Bond - strong attractive force between atoms or ions in a compound. • stability - goal is to reach the most energetically favorable condition • bond energy - energy involved in process of bond forming or bond breaking • Valence Electronsoutermost electrons

3. Highest Energy Level Valence Electrons? 3s23p6

4. How do you represent Valence Electrons? Watch the video clip and fill in examples that you can in your notes

6. How do you represent Valence Electrons? Electron Dot Structures Video Clip 1.What is the atomic number of this element? 2.Write the electron configuration. 3.Identify just the valence electrons (hint use the “A” roman numerals on the periodic table).

7. How do you represent Valence Electrons? Electron Dot Structures 4.Write the symbol for the element. 5.Use a dot for each valence electron. s orbitals on one side p orbitals on remaining three sides of element. Try these examples: Li B N F Be C O Ne

8. 1. shows valence electrons, for example lets try these…… Li B N F Be C O Ne Valence electron

9. Stable Octet (new words, octet rule): 8 electrons in valence shell, stable configuration

10. II. Ionic Bonding: process by which one or more electrons are transferred from the valence shell of one atom to the valence shell of another atom. (usually forms salts)

11. 3s1 3p5 Unstable 3s2 Electons Transferred = ionic bond full octets Electrostatic attraction Stable 11P+ 17P+ 10e- 18e- 1+charge 1- charge

12. Ionic Bonding

13. # of H’s and O’s in molecule 8.3. Names and Formulas for Ionic Compounds (8.3 pgs. 221-227) A. Formulas tell:1. which elements make up the compound (qualitative)2. ratios of atoms contained (quantitative) H2O Hydrogen & Oxygen in element

14. B. Made from a metal + a nonmetal 1. metals form (+) ions - cations 2. nonmetals form (-) ions - anions

15. C. Using ion charge to write formulas 1. write the chemical symbol 2. using the periodic table assign a charge (to be written as a subscript) 1+ 2+ 3+ 3- 2- 1- Group IA, IIA, IIIA, VA, VI, VIIA

16. 3. add charges together to equal zero, use charge of one ion as subscript for the other ion, or use criss-cross method 4. when subscripts are equal they reduce to 1 5. for polyatomics (more than one atom combined that has an overall charge) use parenthesis when subscript is 2 or more

17. examples: Calcium chloride Ca2+ + Cl1- + Cl1-= 0 CaCl2

18. examples: CaCl2 Calcium chloride Aluminum oxide Magnesium sulfide +Al3+ + O2- + O2-+ O2-= 0 Al2O3 Al3+ Mg2+ S2- MgS

19. examples: Magnesium phosphate Mg2+PO43- 3 2 Mg3(PO4)2

20. examples: Barium sulfate Ammonium chloride BaSO4 SO2- Ba2+ NH41+ Cl1- NH4Cl

21. D. Naming ionic compounds 1. binary compounds - two different kinds of atoms a. name the first element b. name the second element, drop the last syllable, add -ide.

22. Sodium Sulfide examples: Na2S = MgO = Magnesium Oxide

23. Naming ternary compounds 2. ternary compounds - name the first element, then name the polyatomic ion

24. Calcium Nitrate examples: Ca(NO3)2 = Na2SO4 = Sodium Sulfate

25. E. atoms that form more than one type of ion (examples: Cu, Fe, Hg, Pb, Sn) 1. old system - call the ion with the greater charge -ic, and the ion with the lesser change -ous. (use Latin names as roots)

26. Old System Cu+1 cuprous CuF cuprous fluoride Cu+2 cupric CuF2 cupric fluoride Fe+2 ferrous FeF2 ferrous fluoride Fe+3 ferric FeF3 ferric fluoride

27. New System – Stock System 2. new system (or stock system), name ion by atom. The name is followed by roman numeral telling its charge.

28. New System – Stock System Cu+1 copper(I) CuF copper (I) fluoride Cu+2 copper(II) CuF2 copper (II) fluoride Fe+2 Iron(II) FeF2 iron (II) fluoride Fe+3 Iron(III) FeF3 iron (III) fluoride

29. III. Properties of Ionic Compounds: Crystal Lattice- three dimensional arrangement of cations & anions List Properties here • Crystal shape • Hard & brittle • High melting pt • High boiling pt • When dissolved, or molten, conducts electricity

30. Properties of Ionic Solids

31. Electrons transferred = ionic bond Electrostatic Attraction

32. Crystal shape Unit cell – simplest, repeating unit

33. IV. Energy and the Ionic Bond: • During any chemical or physical reaction energy is neither created or destroyed • Energy that is absorbed is called endothermic • Energy that is release is called exothermic • The formation of ionic compounds from positive and negative ions is always exothermic. The compound formed is more stable and of lower energy.

34. IV. Energy and the Ionic Bond: • The energy required to separate one mole of the ions of an ionic compound is referred to as the lattice energy. • The more negative the lattice energy, the stronger the force of attraction. • Which would have more negative lattice energy, lithium chloride or lithium bromide? Lithium chloride • MgO is almost four times greater then the lattice energy of NaF, why? MgO, charge of the ions is greater

35. V. Names and Formulas for Ionic Compounds(8.3 pgs. 221-227)(see previous notes) Describe a Pot of Gold (physical and chemical properties of the pot and the gold coins) High lusterHigh Melting/Boiling Pt.MalleableDuctileSolidConductive

36. VI. Metallic Bonds and Properties of Metals (8.4 pgs. 228-231) • Metals form a lattice with eight to 12 other metal atoms surrounding each metal atom. • metals have at least one valence electron, they do not form ions or share their electrons • metals are crowded with electrons and the outer energy levels of the metal atoms overlap

37. VI. Metallic Bonds and Properties of Metals (8.4 pgs. 228-231) • The electron sea model proposed that all the metal atoms in a metallic solid contribute their valence electrons dot form a “sea” of electrons.

38. Electrons are not held tightly by any specific atom, electron are free to move around and are referred to delocalized electrons.

39. The attraction of a metallic cation for delocalized electrons is called a metallic bond.

40. Properties of Metallic Bonding

41. III. How do you name Salts? A. Formulas tell: 1. which elements make up the compound (qualitative) 2. ratios of atoms contained (quantitative)H2O

42. B. Made from a metal + a nonmetal 1. metals form (+) ions - cations 2. nonmetals form (-) ions - anions

43. C. Using ion charge to write formulas 1. write the chemical symbol 2. using the periodic table assign a charge (to be written as a subscript) +1 +2 +3 -3 -2 -1 Group IA, IIA, IIIA, VA, VI, VIIA

44. 3. add charges together to equal zero, use charge of one ion as subscript for the other ion, or use criss-cross method 4. when subscripts are equal they reduce to 1 5. for polyatomics (more than one atom combined that has an overall charge) use parenthesis when subscript is 2 or more

45. examples: Calcium chloride Magnesium phosphate Aluminum oxide Barium sulfate Magnesium sulfide Ammonium chloride CaCl2 Mg3(PO4)2 Al2O3 BaSO4 MgSO4 NH4Cl