1. 1 Chemical Bonding Process of joining atoms together Chemical Bond – Force holding atoms together within a substance Why? – bonding creates a new arrangement of electrons, which is more stable than before. Stable Octet – Arrangement of 8 valence electrons found in Noble gases (2 valence electrons in He)

2. 2 2 types of elements: Metals (Losers) Chemically weakChemically weak Low Ionization energyLow Ionization energy 1, 2, or 3 valence electrons1, 2, or 3 valence electrons Lose electrons in reactionsLose electrons in reactions Na 2-8-1Na 2-8-1 Nonmetals (Gainers) Chemically StrongChemically Strong High Ionization energyHigh Ionization energy 5, 6, 7 valence electrons5, 6, 7 valence electrons gain electrons in reactionsgain electrons in reactions Cl 2-8-7Cl 2-8-7

3. 3 3 Types of “substances” formed Metal (loser) transfers e - to nonmetal (gainer) forming ions  Ionic compoundsMetal (loser) transfers e - to nonmetal (gainer) forming ions  Ionic compounds Nonmetal shares e - w/ Nonmetal (two gainers)  Molecular compounds (and elements)Nonmetal shares e - w/ Nonmetal (two gainers)  Molecular compounds (and elements) Metals – Pure or mixed (losers) Lost e - act to glue ions together  Metallic alloysMetals – Pure or mixed (losers) Lost e - act to glue ions together  Metallic alloys SaltsNaCl Water H 2 O SteelFe,Cr

4. 4 Learning check Identify each sample as ionic, molecular or metallic. 1. CO 2 2. SrO 3. H 2 S 4.Cu 5. Al NO 3 6. C 6 H 12 O 6 7. NaI How does one tell? Notice: in compounds the 2 nd element is a gainer? Is the first element a loser or gainer? Loser = ionic, gainer = molecular Only loser = metallic ex: Cu

5. 5 Ionic Compounds -Made of Ions (Charged “atoms”) Formed when metal atoms transfer electrons to nonmetal atoms Ex: Na atom 2-8-1 - transfers 1 e — to Cl atom 2-8-7 Becomes Na + ion 2-8 and Cl - ion 2-8-8 Both with 8 valence electrons like noble gases: Stable “octet ” Video 4 min

6. 6 Ionic bond: attraction between oppositely charged ions Ex Na + and Cl - in salt NaCl Cation – Positively charged metal ion ex: Na 1+ “sodium” ion Anion – Negatively charged nonmetal ion ex: Cl 1- chloride” ion Name: Sodium Chloride sodium ions bonded to chloride ions

7. 7 Na+ Cl- Na+ Cl- Cl- Na+ Cl- Na+ Na+ Cl- Na+ Cl- Cl- Na+ Cl- Na+ forms solid crystals with equal positive and negative charges so its neutral Properties: Strong continuous chemical bonds = high melting points (above 300 0 C) Where Is the IonicBond? FYI: Most of these compounds are “salts”

8. 8 Ionic properties Brittle: Like charged ions repel when struck Good electrical conductors when dissolved in water NaCl (aq)

9. 9 Learning Check 1.In terms of loss or gain of electrons, how do metals and nonmetals behave differently during reactions? 2.Describe the three types of substances formed from metals and nonmetal elements. 3.Most compounds contain “atoms” with how many valence electrons? Explain. 4.In terms of electrons, how do ionic bonds and ionic compounds form? 5.In terms of forces (bonding), why do salts (ionic compounds) have such high melting points? Why are salts brittle?

10. 10 35 Which of the following solids has the highest melting point? (1) H 2 O(s) (3) SO 2 (s) (2) Na 2 O(s) (4) CO 2 (s) 11 Which type of bond is formed when electrons are transferred from one atom to another? (1) covalent (3) hydrogen (2) ionic (4) metallic 12 Which type of bond is found in sodium bromide? (1) covalent (3) ionic (2) hydrogen (4) metallic

11. 11 “NaCl” is one Formula unit ( “molecule” ) smallest number of ions possible Some are Binary compounds: made of two elements only Ex: MgCl 2, Ex: MgCl 2, magnesium chloride: 1 Mg 2+ with 2 Cl - NOTICE: Positives and negatives balance each other out so compound is neutral Ionic Substances Na+ Cl- Na+ Cl- Cl- Na+ Cl- Na+ Na+ Cl- Na+ Cl- Cl- Na+ Cl- Na+ No separate molecules

12. 12 Learning Check: 1.What kind of substance is NaCl? HDYK? 2. Why don’t we say “one molecule of NaCl”? 3. How many Na + ions would be needed to “neutralize” an O -2 ion? 4. What do you think will be the chemical formula for sodium oxide?

13. 13 Lewis (Electron Dot) Structures – used to show bonding For Elements and Ions – dots or x’s used to represent valence electrons Atoms hydrogen: H Magnesium: Mg e- configuration: 1 2-8-2 Oxygen: O Chlorine: Cl 2-6 2-8-7

14. 14 Lewis structures for ions Ex: IonsEx: Ions Losers: hydrogen HMagnesium: MgLosers: hydrogen HMagnesium: Mg Gainers:Gainers: Oxide: O Chloride: Cl x x x 1+ 2+ [ ] 2- [ ] 1-

15. 15 Learning Check: 1. Draw the Lewis electron dot symbols for the following atoms: a. Nitrogenb. potassiumc. sulfurd. aluminum 2. Draw the Lewis electron dot symbols for the following ions: a. nitride ion b. potassium ion c. sulfide ion d. aluminum ion

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17. 17 Notice: Most gainer ions will end up with 8 dots; Doesn’t matter what the element is. Can you think of an exception? Hydride- [H : ] -1

18. 18 Lewis structures in bonding For Ionic bonding – Metal atoms pass electrons to nonmetal atoms to reach stable octet (8 val. e-) Ex: NaCl: Na + Cl x x becomesNa + [ Cl ] 1-

19. 19 Ionic Bonding MgCl 2 Mg+ Cl Cl becomesMg 2+ [ Cl ] 1- [ Cl ] 1- x x x

20. 20 Practice problems Draw the Lewis e - dot structure for MgO Mg O x OMg 2+ x x [ ] 2-

21. 21 Learning Check: Draw the Lewis electron dot diagrams for the following ionic compounds: a.KF b.K 2 S c.CaF 2

22. 22 Writing formulas and naming compounds  All compounds are made of two parts a “Loser” ……bonded to a …..“gainer” Ionic compounds formulas = Empirical Formulas – Show the lowest whole number ratio of Ions ex: NaCl Ions combine in ratio to become neutral Ex: MgCl 2 : 1 Mg 2+ ion : 2 Cl – ions Ex: NaCl 1 Na : 1 Cl

23. 23 Writing formulas and naming compounds Ex: MgCl 2 : 1 Mg 2+ ion : 2 Cl – ions Naming: named … Magnesium Chloride (negative ions end in ide) Notice: Loser ion (metal first), then gainer ion (nonmetal) Ex: Sodium + oxygenNa 1+ + O 2- (need 2 to balance)Na 1+ Sodium Oxide Na 2 O The 2 is the “Subscript” Notice: No reference is made to how many in the name (We don’t say “disodium oxide”)

24. 24 Writing formulas: Where do you find the charge? Ex: Calcium Chloride Ca +2 Cl -1 CaCl 2 Look at the “oxidation state” (the typical charge)

25. 25 Practice problems: Calcium Bromide Sodium Oxide Strontium Iodide Lithium Nitride Name the following binary compounds: 1.CaBr 2 2.Na 2 O 3.SrI 2 4.Li 3 N Binary compounds: made of only two elements Notice: no reference is made to how many. What are the subscript numbers? Ratios!

26. 26 Practice Write the empirical formula for the following compounds (remember to balance the charges!) Potassium Oxide Magnesium Iodide Calcium sulfide Aluminum chloride Aluminum oxide +1 -2 +2 +2 -2 +3 +3-2 K2OK2OK2OK2O MgI 2 CaS AlCl 3 Al 2 O 3 K2OK2OK2OK2O+1-2 Ca 2 S 2 ? Simplify to lowest ratio NEVER leave charges on formulas!

27. 27 Transitional metals – many with multiple charges Use the “stock” system Roman numerals which represent the charge of the positive ion Transition elements can lose e - from outer and inner sublevels Ex: Cu 1+  “copper one” ion vs. Cu 2+  “copper two” ion Copper(I) Oxide Cu 1+ +O 2- 2 Cu 1+ +O 2- Cu 2 O Which Copper oxide ?  Cu O Cu = +2 Copper(II) oxide -2 +2

28. 28 Ex: Fe 2 O 3 Fe can be +2 or +3 so need to distinguish Slice up into loser and gainer Fe ? 2 | O 3 Identify the charge on the gainer Fe ? 2 | O 2- 3 Iron(III) oxide 3(-2) = -6+6 2 = +3

29. 29 Practice problems: name the following 1. Cu I 2. Cu I 2 3. Hg O 4. Hg 2 I 2 +1 Copper (I) iodide +2 Copper (II) iodide -2 +2 Mercury (II) oxide +2 +1 Mercury (I) Iodide ___ 2 -2 Hg 2 +2 Mercury “one” ion A “poly-atom-ic” ion

30. 30 19 Which formula correctly represents the composition of iron (III) oxide? (1) FeO 3 (3) Fe 3 O (2) Fe 2 O 3 (4) Fe 3 O 2

31. 31 Test your learning Name these: 1. Na 2 O 2. MgI 2 3. PbI 4 4. Hg 2 I 2 Write formulas: 1. potassium oxide 2. Calcium nitride 3. Lead (II) iodide 4. Copper (I) sulfide Draw Lewis structures for each #2 above

32. 32 Polyatomic ions Ternary Compounds are large compound ions that stay together as one unit ex: ammonium NH 4 + click on the slide

33. 33 Polyatomic ions In Ternary Compounds (contain 3 or more elements) ex: NaOH Sodium hydroxide

34. 34 Polyatomic ions (charged “molecule”) Most Names end in -ate or –ite means its bonded with oxygen. Ex: SO 4 2-  called “sulfate” ion As in copper sulfate = CuSO 4 SO 3 2-  “sulfite” ion NO 3 1-  “Nitrate” ion As in potassium nitrate = KNO 3 NO 2 1-  “Nitrite” ion Notice: -ates have more oxygen and –ites have less.

35. 35 Ex: sodium sulfate Na+ + SO 4 2- 2Na+ + SO 4 2- Na 2 SO 4 Ex:ammonium Carbonate NH 4 + + CO 3 2- 2 NH 4 + + CO 3 2- (NH 4 ) 2 CO 3 Notice: (NH 4 ) Parentheses are used if more than one ion is represented – subscript comes after Two ammonium ions bond for every one carbonate

36. 36 Naming Problems 1. Na 2 CrO 4 2. K 2 Cr 2 O 7 3. (NH 4 ) 2 S 4. NaOH 5. Ca(OH) 2 6. CaSO 4 7. CaSO 3 Sodium Chromate Potassium Dichromate Ammonium sulfide Sodium hydroxide Calcium hydroxide Calcium sulfate Calcium sulfite (most compounds split after the first element)

37. 37 formula problems Write the formulas of these ternary compounds: Magnesium sulfate Aluminum nitrate Copper (II) carbonate Zinc acetate Ammonium chloride +2 -2 Mg SO 4 +3 Al NO 3 +2-2 Cu CO 3 +2 Zn C 2 H 3 O 2 +1 NH 4 Cl ( ) 3 ( ) 2

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39. 39 Test your learning Name these: 1. NaC 2 H 3 O 2 2. Fe(ClO 3 ) 2 3. K 3 PO 4 4. SnO 2 5. Na 2 O 2 Write the formula: 1. Mercury(II) chlorite 2. Calcium carbonate 3. Ammonium sulfide 4. Lead (II) oxalate 5. Potassium permanganate