1. Calculating Chemical Equations Why and How Many Atoms Bond

2. Counting Atoms A Chemical Formula shows how many of which atoms are in a molecule A Subscript is a number placed below and behind a symbol to show how many of which atoms are present H2OH2O

3. Counting Atoms A Coefficient is placed in front of a molecule to show more than one molecule 3H 2 O

4. Counting Atoms A Diatomic Molecule shows two atoms of the same nonmetal (usually in gas form) that have bonded together Reactive nonmetals will bond with one another if no other substance is available for bonding H2N2H2N2H2N2H2N2 O2F2O2F2O2F2O2F2 I 2 Cl 2 Br 2

5. Polyatomic Ions A group of atoms that behave as one atom Keep together as a unit Listed on p. 619 If more than one polyatomic ion is present in a molecule, parentheses set it apart Still use a subscript to show how many Ca(OH) 2 NH 4 Cl

6. Counting Atoms Write the molecule to be counted List the participating atoms (or polyatomic ions) under the formula Write all subscripts, including parentheses Multiply by the coefficient Some problems call for a total of atoms, some call for individual atoms

7. How many total atoms are in Methane, CH 4 ? 1234567891011121314151617181920 212223242526272829303132 1.2 2.3 3.4 4.5 5.6 20

8. How many atoms of Chlorine are in Carbon Tetrachloride, CCl 4 ? 1234567891011121314151617181920 212223242526272829303132 1.2 2.3 3.4 4.5 5.6 20

9. How many total atoms are in Magnesium Hydroxide, Mg(OH) 2 ? 1234567891011121314151617181920 212223242526272829303132 1.2 2.3 3.4 4.5 5.6 20

10. How many atoms of Oxygen are in Acetic Acid, CH 3 COOH? 1234567891011121314151617181920 212223242526272829303132 1.2 2.3 3.4 4.5 5.6 20

11. How many total atoms are in Acetic Acid, CH 3 COOH? 1234567891011121314151617181920 212223242526272829303132 20 1.4 2.5 3.6 4.7 5.8 6.9

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13. Oxidation Numbers A positive or negative sign used to show what type of ion is formed after an atom has gained or lost enough electrons to be chemically stable Written like a charge sign (upper right) Always included with a list of polyatomic ions

14. BASE OXIDATION NUMBERS BY GROUP +1 0 +2 +3 ±4 -3 -2 -1 USE ROMAN NUMERALS

15. What is the Oxidation Number for Sulphur (Group 16)? 1234567891011121314151617181920 212223242526272829303132 1.+1 2.+2 3.+3 4.4 5.-3 6.-2 7.-1 20

16. What is the Oxidation Number for Aluminium (Group 13)? 1234567891011121314151617181920 212223242526272829303132 1.+1 2.+2 3.+3 4.4 5.-3 6.-2 7.-1 20

17. What is the Oxidation Number for Potassium (Group 1)? 1234567891011121314151617181920 212223242526272829303132 1.+1 2.+2 3.+3 4.4 5.-3 6.-2 7.-1 20

18. What is the Oxidation Number for Chlorine (Group 17)? 1234567891011121314151617181920 212223242526272829303132 1.+1 2.+2 3.+3 4.4 5.-3 6.-2 7.-1 20

19. What is used to show the Oxidation Number for Transition Metals (Groups 3 – 12)? 1234567891011121314151617181920 212223242526272829303132 20 1.Alchemical Symbols 2.Transition Icons 3.Arabic Numerals 4.Roman Numerals 5.Hieroglyphics 6.Kanji

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21. Making formulæ “The Criss-Cross Method” Write the element with the positive oxidation number Write the element with the negative oxidation number Rewrite the two symbols together below the symbols with their oxidation number Drop the positive or negative sign Write the oxidation number from one symbol on the other symbol as a subscript

22. The Criss Cross Method cont’ Remember to add parentheses for polyatomic ions Don’t write “1”s Reduce any evenly-divisible subscripts

23. What is the correct formula for a bond between Carbon and Hydrogen? 1234567891011121314151617181920 212223242526272829303132 1.CH 2.C 2 H 2 3.CH 3 4.C 2 H 3 5.CH 4 40

24. What is the correct formula for a bond between Sodium and Nitrogen? 1234567891011121314151617181920 212223242526272829303132 1.NaN 2.Na 2 N 2 3.Na 3 N 4.Na 2 N 3 5.Na 3 N 4 40

25. What is the correct formula for a bond between Calcium and Chlorine? 1234567891011121314151617181920 212223242526272829303132 1.CaCl 2.Ca 2 Cl 2 3.Ca 2 Cl 4.CaCl 2 5.Ca 3 Cl 4 40

26. What is the correct formula for a bond between Sodium and Hydroxide? 1234567891011121314151617181920 212223242526272829303132 1.NaOH 2.Na(OH) 2 3.Na(OH) 3 4.Na 2 (OH) 3 5.Na(OH) 4 40

27. What is the correct formula for a bond between Aluminum and Sulfate? 1234567891011121314151617181920 212223242526272829303132 1.AlSO 4 2.Al 2 (SO 4 ) 2 3.Al 2 (SO 4 ) 3 4.Al 3 (SO 4 ) 3 5.Al(SO 4 ) 4 40

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29. Binomial Nomenclature Naming a two-part name Used to differentiate between Fluorine (an element) and Fluoride (part of a compound) Never change the name of a Polyatomic Ion Big difference between Sulfide and Sulfite

30. Ionic Compounds List the positive ion (or metal) first Use Roman Numerals to show the Oxidation number of a transition metal Begin the negative ion (or nonmetal), changing the ending to –ide Oxide Sulfide Phosphide

31. Covalent Compounds Prefixes are used to show how many of which atoms Prefixes are number-words from Greek & Latin Write the name of the first atom Add a prefix only if there is more than one of the first Write the name of the second atom Add a prefix showing how many of the second are present Change the ending to -ide

32. Numbering Prefixes 1 – Mono- 2 – Di- 3 – Tri- 4 – Tetra-, 5 – Penta- 6 – Hexa- 7 – Hepta- 8 – Octa- 9 – Nona- 10 – Deka-

33. What is the name for N 2 O 4 ? 1234567891011121314151617181920 212223242526272829303132 1.Nitrogen Oxide 2.Dinitrogen Oxide 3.Dinitrogen Dioxide 4.Dinitrogen Tetraoxide 5.Nioxx (Nioxalate) 20

34. What is the name for Na 2 S? 1234567891011121314151617181920 212223242526272829303132 1.Sodium Sulfide 2.Sodium Sulfite 3.Sodium Sulfate 4.Disodium Sulfide 5.Disodium Sulfate 20

35. What is the name for CO 2 ? 1234567891011121314151617181920 212223242526272829303132 1.Carbon Oxide 2.Carbon Dioxide 3.Monocarbon Oxide 4.Monocarbon Dioxide 5.Mi-Bref (B-hot) 20

36. What is the name for ( NH 4 ) 2 O? 1234567891011121314151617181920 212223242526272829303132 1.Nitrogen Hydrogen Oxide 2.Mononitrogen Tetrahydrogen Oxide 3.Ammonium Oxide 4.Diammonium Oxide 5.Ammonium Oxalate 20

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38. Chemical Equations A shorthand way to describe a chemical reaction using chemical symbols and formulæ

39. Chemical Equations Has three parts Reactants Substances present before the reaction Products Substances present after the reaction Yield Arrow Indicates the direction of a reaction Some reactions are reversible

40. Writing a Chemical Equation Chemical symbols give a “before-and-after” picture of a chemical reaction ReactantsProducts MgO + CCO + Mg magnesium oxide to form carbon monoxide reacts with carbon and magnesium

41. Balancing Chemical Equations Equations must be balanced to observe the Law of Conservation of Matter Matter can not be created or destroyed under normal reactions If you begin a reaction with 5 g of Hydrogen, you must end up with 5 g of Hydrogen

42. A Balanced Chemical Equation Same numbers of each type of atom on each side of the equation Al + S Al 2 S 3 Not Balanced 2Al + 3S Al 2 S 3 Balanced

43. Balancing Chemical Equations Count atoms on both sides of the yield arrow Determine which elements are unequal Use coefficients to balance the number of atoms on both sides If you multiply one element in a compound, you multiply both elements in a compound You can treat Polyatomic Ions as one if they appear on both sides of the equation Go for the highest unequal elements first Leave solitary elements for last

44. Steps in Balancing An Equation Fe 3 O 4 + H 2 Fe + H 2 O Fe: Fe 3 O 4 + H 2 3 Fe + H 2 O O:Fe 3 O 4 + H 2 3 Fe + 4 H 2 O H: Fe 3 O 4 + 4 H 2 3 Fe + 4 H 2 O

45. Balancing Chemical Equations Mg + N 2 Mg 3 N 2 Al + Cl 2 AlCl 3

46. Balancing Chemical Equations Fe 2 O 3 + C Fe + CO 2 Al + FeO Fe + Al 2 O 3 Al + H 2 SO 4 Al 2 (SO 4 ) 3 + H 2

47. Types of Chemical Reactions Synthesis Two or more substances form one new substance H 2 +O 2  H 2 O N 2 +H 2  NH 3

48. Types of Chemical Reactions Decomposition One substance breaks down to form two or more new substances PbCO 3  PbO+CO 2 H 2 CO 3  H 2 O+CO 2

49. Types of Chemical Reactions Single Displacement One substance replaces another in a compound Li+AlCl 3  LiCl+Al

50. Types of Chemical Reactions Double Displacement Two substances “swap partners” in two compounds KOH+HBr  KBr+H 2 O NaOH + H 2 CO 3  Na 2 CO 3 + H 2 O

51. Types of Chemical Reactions Neutralization Double-displacement reaction where an acid and a base form a salt and water KOH+HBr  KBr+H 2 O NaOH + H 2 CO 3  Na 2 CO 3 + H 2 O

52. Acids and Bases Acids Taste Sour Have a pH of less than 7 Produce Hydronium H 3 O +1 in solution Have an “extra” H- on the beginning of the formula H 2 SO 4 – (Hydro)Sulfuric Acid H 3 PO 4 – (Hydro)Phosphoric Acid HNO 3 – (Hydro)Nitric Acid HCl – Hydrochloric Acid

53. Acids and Bases Bases Taste bitter Have a pH of more than 7 Produce Hydroxide OH –1 in solution Have an –OH on the end of the formula NaOH – Sodium Hydroxide KOH – Potassium Hydroxide Ca(OH) 2 – Calcium Hydroxide NH 4 OH – Ammonium Hydroxide

54. The Litmus Test Using an indicator can tell whether a substance is acidic or alkaline Litmus paper is a frequently-used indicator Acids turn BLUE litmus paper RED Bases turn RED litmus paper BLUE

55. Types of Chemical Reactions Combustion Where a carbon compound combusts with oxygen gas to form carbon dioxide and water CH 4 + O 2  CO 2 + H 2 O C 2 H 6 + O 2  CO 2 + H 2 O

56. Let’s get it started Some reactions require a little “jump start” to proceed Activation Energy Energy required to be applied to start a reaction Examples Applying friction to start a match The match causing a log to burn

59. Change in ENERGY Every reaction has some change in energy Two possibilities:

60. Endothermic – absorbs energy from the environment to complete reaction Feels “COLD” to its surroundings Products have MORE energy than the reactants

62. Exothermic – releases energy to the environment as the reaction proceeds Feels “HOT” to its surroundings Products have LESS energy than reactants

64. Speeding Up A Catalyst is a chemical that participates in a chemical reaction without being changed by the reaction Catalysts speed up reaction rates by acting as a “convenience” lowering the activation energy Organic catalysts are called ENZYMES

65. Hungry? Without enzymes, your cells would NEVER keep up with the energy demands

66. Slowing Down An Inhibitor also participates in a chemical reaction without being changed by the reaction Inhibitors slow down reaction rates by acting as an “inconvenience” raising the activation energy

67. Normal reaction / normal activation energy With a catalyst / lower activation energy

68. Counting Atoms Subscripts Coefficients Diatomic Molecules Polyatomic Ions Parenthesis Oxidation Numbers Binary Formulæ Criss-cross method Naming Rules Ionic Roman Numerals Covalent Prefixes Balancing Equations NEVER change subscripts Law of Conservation of Matter Types of Reactions Changes in Energy during reactions