3. Bonds involve the Valence Electrons a)Valence electrons = only outer energy level electrons b)Atoms want a full outer energy level like the Noble gas atoms c)For most atoms full = 8 electrons. d)Group #A = # of valence electrons

4. Lewis Dot Structures Symbols of atoms with dots to represent the valence-shell electrons 1A 2A 3A 4A 5A 6A 7A 8A H  He:            Li  Be   B   C   N   O  : F  : Ne :                    Na  Mg   Al   Si   P   S  : Cl  : Ar :        

5. Learning Check A. X would be the electron dot formula for 1) Na2) K3) Al B. X would be the electron dot formula 1) B2) N3) P

6. Chemical bonds: an attempt to fill valence electron shells TypeIonicCovalentMetallic Electronegativity differences High (bully atoms steal electrons from wimpy atoms) Very low (bully atoms share with bully atoms since neither will give up electrons) Low (all are wimpy atoms so they just let their electrons freely float) Forms betweenMetal atoms and nonmetal atoms Only between nonmetal atoms Only between metals How formedValence electrons are transferred from metal to nonmetal atom Valence electrons are shared between atoms Valence electrons freely float around all metal nuclei (“sea of electrons”) Other factsForms compoundsForms moleculesForms alloys

7. IONIC BOND bond formed between two ions by the transfer of electrons

8. Formation of Ions from Metals Ionic compounds result when metals react with nonmetals Metals lose electrons to match the number of valence electrons of their nearest noble gas Positive ions form when the number of electrons are less than the number of protons Group 1A metals  ion 1+ Group 2A metals  ion 2+ Group 3A metals  ion 3+

9. Formation of Sodium Ion Sodium atom Sodium ion Na  – e   Na + 2-8-1 2-8 ( = Ne) 11 p + 11 p + 11 e - 10 e - 0 1 +

10. Formation of Magnesium Ion Magnesium atom Magnesium ion  Mg  – 2e   Mg 2+ 2-8-2 2-8 (=Ne) 12 p + 12 p + 12 e- 10 e - 0 2 +

11. Some Typical Ions with Positive Charges (Cations) Group 1Group 2Group 13 H + Mg 2+ Al 3+ Li + Ca 2+ Na + Sr 2+ K + Ba 2+

12. Learning Check A. Number of valence electrons in aluminum 1) 1 e - 2) 2 e - 3) 3 e - B. Change in electrons to obtain the octet 1) lose 3e - 2) gain 3 e - 3) gain 5 e - C.Ionic charge of aluminum 1) 3- 2) 5- 3) 3 +

13. Solution A. Number of valence electrons in aluminum 3) 3 e - B. Change in electrons for octet 1) lose 3e - C.Ionic charge of aluminum 3) 3 +

14. Learning Check Give the ionic charge for each of the following: A. 12 p + and 10 e - 1) 02) 2+3) 2- B. 50p + and 46 e- 1) 2+2) 4+3) 4- C. 15 p + and 18e- 2) 3+ 2) 3-3) 5-

15. Ions from Nonmetal Ions In ionic compounds, nonmetals in 5A, 6A, and 7A gain electrons from metals Nonmetal add electrons to achieve the octet arrangement Nonmetal ionic charge: 3-, 2-, or 1-

16. Fluoride Ion unpaired electronoctet     1 - : F  + e  : F :     2-7 2-8 (= Ne) 9 p+ 9 p + 9 e- 10 e- 0 1 - ionic charge

17. Ionic Bond Between atoms of metals and nonmetals with very different electronegativity Bond formed by transfer of electrons Compounds have high melting points. Examples; NaCl, CaCl 2, K 2 O

19. Ionic Bonds: One Big Greedy Thief Dog!

20. 1). Ionic bond – electron from Na is transferred to Cl, this causes a charge imbalance in each atom. The Na becomes (Na+) and the Cl becomes (Cl-), charged particles or ions.

21. Forms a crystal lattice

22. COVALENT BOND bond formed by the sharing of electrons

23. Covalent Bond Between nonmetallic elements of similar electronegativity. Formed by sharing electron pairs Examples; O 2, CO 2, C 2 H 6, H 2 O, SiC

25. 2. Covalent bonds- Two atoms share one or more pairs of outer-shell electrons. Oxygen Atom Oxygen Molecule (O 2 ) Oxygen Molecule (O 2 )

26. METALLIC BOND bond found in metals; holds metal atoms together very strongly

27. Metallic Bond Formed between atoms of metallic elements Electron cloud around atoms Good conductors at all states, lustrous, very high melting points Examples; Na, Fe, Al, Au, Co

28. Metallic Bonds: Mellow dogs with plenty of bones to go around.

29. Metallic Bond, A Sea of Electrons

30. Learning Check Decide the type of bond NaCl; Ionic Bond C 2 H 6 ; Covalent Bond Bronze; Metallic

31. Properties of Metals ++++ ++++ ++++ Electrons are free to move through the solid, so..... Metals conduct electricity and heat Solids at room temperature (except Hg) High melting points (200˚C and above) Malleable Ductile

32. Malleable ++++ ++++ ++++ Force

33. Malleable ++++ ++++ ++++ Mobile electrons allow atoms to slide by, sort of like ball bearings in oil. Force

34. Properties of ionic compounds Crystalline structures (repeated patterns of + and – ions) Are crystalline solids at room temperature Extremely high melting points Are hard and brittle – they break under pressure. +-+- + - +- +-+- + - +-

35. Ionic solids are brittle +-+- + - +- +-+- + - +- Force

36. Ionic solids are brittle + - + - + - +- +-+- + - +- Strong Repulsion breaks a crystal apart, due to similar ions being next to each other. Force

37. Do they Conduct? Conducting electricity means allowing charges to move. In a solid, the ions are locked in place. Ionic solids are insulators. When melted, the ions can move around. lMelted ionic compounds conduct. –NaCl: must get to about 800 ºC. Dissolved in water, they also conduct (ions separate and are free to move in solutions)

38. - Page 198 The ions are free to move when they are molten (or in aqueous solution), and thus they are able to conduct the electric current.

39. Structure of Ionic Compounds

41. Alright something for the guys too!