Chemical Bonding

1. Chemical Bonding 1 Adventures of Oxygen Clip

2. 2 GOALS 1. Compare & contrast ionic and covalent bonds in terms of electron position. 2. Predict formulas for stable binary ionic compounds based on balance of charges. 3. Determine the Types of ions formed by representative elements 4. Apply the Law of Conservation of Matter by balancing the following types of chemical equations: • Synthesis • Decomposition • Single Replacement • Double Replacement 34 16

3. 3 Why do Atoms Form Compounds? • Stability. • What makes an atom stable? • Full outer energy level. • Eight. • They can either…… • 1) Gain electrons • 2) Lose electrons • 3) Share electrons

4. 4 • A Chemical Bond holds atoms together in a compound. • Two basic types: 1. Ionic 2. Covalent

5. Ionic Bonding 5 Transfer of electrons from one atom to another atom. Occurs between metals & nonmetals. Remember: Atoms need a full outer energy level to be stable. EIGHT! Called compounds.

6. 6 Ionic Bonding Occurs between metals and nonmetals. Metals are electron donors. SO, they become POSITIVE Non-metals are electron accepters. SO, they become NEGATIVE. OPPOSITS ATTRACT!

7. 7 When Atoms gain or lose electrons, they are called Ions. 3P 3P 3P Anion 3P 3P 3P Cation

8. 8 • Metals lose electrons to become stable. • Nonmetals gain electrons to become stable.

9. 9 Atoms can gain or lose electrons Ionization: requires energy Why do atoms lose and gain electrons? To become more stable. Stability=full outer energy level

11. 11 OPPOSITS ATTRACT!

12. 12 Properties of Ionic Compounds • Crystalline solids at room temperature. • Arranged in repeating three-dimensional patterns • Have high melting points • Can conduct electricity when melted or dissolved in water

13. 13 Ionic Bonding CLIP

14. 14 Covalent Bonding The sharing of electrons between atoms. Occurs between nonmetals and nonmetals. Called Molecules.

15. 15

16. 16 Hydrogen and Fluorine Hydrogen and Chlorine

17. 17 Single, Double, Triple 2 e- 4e- 6e-

18. 18 Clip

19. 19 Unequal Sharing Called Polar δ+ δ_ Polar molecules happen when one atom has a greater positive charge

20. 20 Properties of Covalent Molecules • Many are gases or liquids at room temperature • Composed of two nonmetals. • Have low melting and boiling points

21. Ionic and Covalent Bonding Review Clip

22. CO2 NaCl H2O MgCl2 NO2 Li2S NaF BeO HCl NaF KCl H2O2 N2 Cl2 21 Covalent or Ionic?(write the formula, then write “C” or “I” clip

23. Writing Chemical Formulas Goals revisited

24. 22 • Writing chemical formulas is a shorthand way of indicating what a substance is made of.  • These formulas also let you know how many atoms of each type are found in a molecule.  The chemical formula for water is H2O.  Carbon Dioxide is CO2.  Why does oxygen combine in different ratios, in different compounds?  The chemical formula for table salt is NaCl. Calcium Chloride is CaCl2. Why does chlorine combine in different ratios, in different compounds? 

25. 23 The simplest compounds are ones with only two elements These are called binary KI, CO, H2O, NaCl

26. Oxidation numbers +4 -4 +1 0 Tell you how many electrons an atom must gain, lose or share to become stable. -2 +2 +3 -3 -1 24

27. 25 Oxidation numbers We can predict the ratio of atoms in ionic compounds based on their oxidation numbers +1 -1 1 valence electron K Cl 7 valence electron All compounds are neutral Tells you how many electrons an atom must gain, lose or share to become stable. KCl That means the overall charge is ZERO!

28. +1 -1 +2 -1 Na Br Ca Br To make it ZERO, you need 1 Ca & 2 Br. NaBr CaBr2 Subscripts show the number of atoms of that kind in the compound 26

29. K + Br Mg + Cl Ca + I K + O K + I Sr + Br Na + O Ga + Br Mg + O Al + P 27 Now You Try writing Binary Ionic formulas

30. Some elements have more than one oxidation number(Chart p588) +3 -2 +2 -2 Fe O Fe O Fe2O3 FeO We call these elements- Multivalent Elements 28

31. Fe+2 + O Fe+3 + O Cu+2 + F Cr+3 + O 29 Multivalent Practice

32. 30 Polyatomic Ions Groups of Covalently Bonded atoms that stay together.

33. Na + SO4 Mg + PO4 Ca + CO3 Na + OH Mg + OH NH4 + OH K + PO4 NH4 + NO3 H + SO4 Ca + SO4 K + NO3 Na + PO4 31 Try these……p591 Mixed Practice

34. Naming Chemical Formulas

35. Naming Binary Compounds and Molecules 32 • Steps: • If it is Binary- • Decide if it is an ionic or covalent bond. • Metal- nonmetal….. • Ionic • Nonmetal- nonmetal…. • Covalent Example: • NaCl

36. Check to see if any elements are multivalent or polyatomic. If all single valent, write the name of the positive ion first. Write the root of the negative ion and add –ide. Examples: NaCl K2O AlCl3 BaF2 KI Li2O If ionic ……. 33

37. If ionic ……. 34 Examples: • FeO • Fe2O3 • CuO • Cu2O • PbCl4 • PbI2 • Check to see if any elements are multivalent. • If multivalent ions, determine the oxidation number of the element. • Use Roman numerals in parentheses after the name of the element. • Write the root of the negative ion and add –ide.

38. Write the name of the positive ion. Write the name of the polyatomic ion. Examples: NaCO3 KNO3 NaC2H3O2 35 If it contains a polyatomic ion... Example: • KOH • Potassium Hydroxide • CaCO3 • Calcium Carbonate

39. Use Greek prefix to indicate how many atoms of each element are in the molecule Add -ide to the more electronegative element Greek Prefixes 1- mono- 2- di- 3- tri- 4- tetra- 5- penta- 6- hexa- 7- hepta- 8- octa- 36 If Covalent... Example: • NO • Nitrogen Monoxide • PCl3 • Phosphorous trichloride

40. KBr HCl MgO CaCl2 H2O NO2 CuSO4 CaSO4 NH4OH CaCO3 Cu(ClO3) 2 Cr2O 3 FeO 14. LiBr 15 MgCl 37 Name the following:Mixed Practice

41. 38 Writing & Balancing Chemical Equations Goals revisited

42. 39 Chemical Reactions • A chemical reaction is a change in which one or more substances are converted into new substances. • Rearrangement of bonds in compounds and molecules. • Chemical Equations make it possible to see clearly what is happening during a chemical reaction

43. 40 Chemical equations are a shorthand way to show chemical reactions. Reactants Products H2 + O2 H2O

44. 41 Conservation of Mass The mass of the products always equals the mass of the reactants

45. 42 H2 + O2 H2O Does this meet the Conservation of Mass Law? 2 Hydrogen atoms 2 Oxygen atoms 2 Hydrogen atoms & one Oxygen atom Must Balance the Equation to show Conservation of Mass.

46. 43 Can add coefficients to Balance equations. 2 H2 + O2 2 H2O 2 4 2 4 2 1 2 Balanced!! Steps: 1. Count Atoms on both sides 2. If not Balanced, add coefficients to balance. 3. Recount atoms after adding each coefficient. 4. Keep adding coefficients until balanced.

47. 44 Types of Chemical Reactions

48. 45 Chemical Reactions • You start with one or more compounds and turn it into different compounds. Vapors of hydrogen chloride in a beaker and ammonia in a test tube meet to form a cloud of a new substance, ammonium chloride.

49. 46 • Synthesis • Decomposition • Single Replacement (Single Displacement) • Double Replacement(Double Displacement)

50. Synthesis “to make” A + B AB Cu + O CuO 2H2 + O2 2H2O