Notes

1. Rates of Reactions Types of Reactions Balancing Equations Chemical Reactions Covalent Bonds Ionic Bonding Review Notes

2. Chemical Bonding • A chemical bond is when two or more atoms or ions are strongly attached to each other. • Ionic Bond – electrostatic force holding oppositely charged ions together • Covalent Bond – the sharing of electrons between two atoms to hold them together • Metallic Bond – a bond found amongst metals where there is a ‘sea’ of metal ions amid freely floating electrons.

3. Chemical Bonding • Ionic Bond – generally between metals and nonmetals • Covalent Bond – generally between nonmetals and nonmetals • Metallic Bond – formed between metals and metals

4. Ionic Bonding Review • Ion – a charged particle • Atoms can become charged when they gain or lose electrons. • Gain electrons = more negatively charged • Lose electrons = more positively charged • Oppositely charged particles are attracted to each other

5. Periodic Table Shortcuts

6. Gainers and Losers • You can think about different atoms based on how many electrons they will gain or lose. • Gainers – Elements who need to gain electrons to become happy/stable. • Elements in Groups: • Losers – Elements who lose electrons to become stable. • Elements in Groups:

7. Compounds – opposites attract! • Positive Ions will attract Negative Ions. • A +1 ion will equally bond with a -1 ion. • A +2 ion will equally bond with a -2 ion. • What happens when a +2 ion encounters a -1 ion? • Gainers and Losers Bond together to form ionic compounds

8. Formation of Ionic Bond

9. Formation of Ionic Bond

10. Formation of Ionic Bond

11. Formation of Ionic Bond

12. Covalent Bonds

13. Covalent Bonding? • Timmy and Suzy are at their grandma’s house and they both have an 8 pack of colored pencils. Timmy is missing his red pencil and Suzy is missing her green pencil. How can they finish their pictures without a full set of their own colored pencils?

14. Formation of Covalent Bond • Covalent bonding • The mutual attraction and repulsion forces between the protons (+) and electrons (-) hold two atoms together. - + + -

15. Reading Covalent Bonds • For each atom, there needs to be an EDD • Each line always represents TWO SHARED electrons • This means that BOTH atoms can count them when determining if they are stable/happy. • Each dot that represents a valence electron

16. Reading Covalent Bonds _ Br Br • The chemical formula is _________. • The type of bond is (IONIC or COVALENT). • Each bond contains _____electrons. • How many electrons are being SHARED total? ________ • How many electrons are NOT being shared? ______ • How many bonds are between Br and Br? ______ • Yes or No: Are each of the atoms happy? (Circle the electrons/bonds if it helps you).

17. Steps for making Covalent Bonds • Figure out how many atoms of each element you need. [Normally given by the formula] Draw the electron dot diagram for each of the atoms separately. • Decide how many electrons each atom wants to GAIN to have a full outer energy level! • Line up the electrons to get ready to share. • For each two electrons that will be shared, replace the dots with a bond (a line). Continue until each is atom “happy” when you count shared and any remaining valence electrons.

18. N N O O O O O O

19. O O O O

20. Chemical Reactions

21. Vocabulary Review • Physical Change – A change in size, shape, or state of an object, yet does not change the actual object. • Chemical Change – A change from one substance into another with different properties. Evidence includes: changes incolor, odor, size, or energy either received or given off.

22. Vocabulary • Chemical Reaction – A process of chemical change occurring when compounds change bonds and creating new, different substances. • Chemical Equation – the explanation of a chemical reaction using symbols and numbers to show the atoms involved. • Reactants – Substances that exist before a reaction. • Products – Substances that are formed from a reaction.

23. Understanding Chemical Equations The point of a formula is to sum up and quickly explain a reaction that would otherwise be too long winded. The reactants of one molecule of methane and two oxygen molecules produces the products of one carbon dioxide molecule and two molecules of dihydrogen monoxide. produces CH4 + O2 + O2 CO2 + H2O +H2O Reactants Products

24. Understanding Chemical Equations CH4 + O2 + O2 CO2 + H2O +H2O Reactants Products is the same equation as 1 CH4 + 2 O2 1 CO2 + 2 H2O is the same equation as CH4+ 2O2 CO2+ 2H2O

25. Counting Atoms in Reactions 1 1 4 4 4 4 2 + 2 =

26. 6) Are atoms created or destroyed in a chemical reaction? How do you know? What does the picture on the right represent? Atoms are not created or destroyed. There is exactly the same number of each type of atom in the products as there are in the reactants. The products “balance” the reactants. There are exactly the same number of reactant atoms as there are product atoms. Furthermore, the mass on the left equals the mass on the right.

27. 7) In a physical change, like changing state from a solid to a liquid, the substance itself doesn’t really change. Explain how is a chemical change different from a physical change? In a chemical change a newsubstance with different properties is formed, but in a physical change it only changes size, shape, or state.

28. More Counting Atoms 3 3 8 8 10 10 6 + 4 =

29. 4 8 20 10 26 26 16 + 10 = When Balancing… YOU CAN NEVER CHANGE THE NUMBER IN THE SUBSCRIPTS. ONLY COEFFICIENTS

30. Conservation of Mass • When a chemical reaction happens, no atoms are created or destroyed. • The number of atoms in the reactants ALWAYS EQUALS the number of atoms in the products. • For a chemical equation to be correct, the equation must be balanced.

31. Visualizing Equations!

32. Visualizing Equations • CH4 + O2  CO2 + H2O Not a Real Reaction H H O C O H H ? CO2 + H2O CH4 + O2

33. Visualizing Equations • CH4 +2O2  CO2 + 2H2O Combustion H H O O C O O H H CO2 + 2H2O CH4 + 2 O2

34. Visualizing Equations • H2 + O2 H2O H H O O H2+ O2 H2O? Not a Real Reaction

35. Visualizing Equations • 2 H2 + O2 2H2O H H H H O O 2 H2+ 1O2 2H2O Synthesis 2 H2 + O2 2H2O

36. Visualizing Equations • NH3 N2 + H2 Not a real reaction H N H H ? N2 + ? H2 NH3

37. Visualizing Equations • 2NH3 N2 + 3H2 Decomposition H H N N H H H H N2 + 3H2 2NH3

38. Visualizing Equations Single Replacement • Zn + H2SO4 + ZnSO4 + H2 H H O O S Zn O O ZnSO4 + H2 Zn + H2SO4

39. Visualizing Equations Not a real Reaction • K2S + HBr KBr + H2S K H S Br K • ? KBr + ? H2S K2S + HBr

40. Visualizing Equations Double Replacement • K2S + 2HBr  2 KBr + H2S K H H S Br Br K • 2 KBr + H2S K2S + 2HBr

41. Visualizing Equations • HCl + NaOH NaCl + H2O Acid Base Na Cl H O H • NaCl + H2O HCl + NaOH

42. Balancing Equations • More worked examples are found on the teacher website.

43. Worked Examples N2 + H2 NH3 N H KClO3KCl + O2 K Cl O

44. Worked Examples NaCl + F2NaF + Cl2 Na Cl F H2+ O2 H2O H O

45. What is a chemical change? A chemical change is when a newsubstance with different properties is formed from the reaction of the REACTANTS.

46. Types of Reactions • Synthesis: (Building something) A+B AB Example 2H2 + O2 2H2O End with 1 Product • Decomposition: (Destroying something) AB  A +B Example 2NH3  N2 + 3H2 Begin with 1 Reactant

47. Types of Reactions 3. Single Replacement: AX + B A + BX Example 2K + MgBr22KBr + Mg Switch one partner 4. Double Replacement: AX + BY  AY + BX Example 2 AlBr3+ 3 K2SO46 KBr + Al2(SO4)3 Switch both Partners

48. Types of Reactions 5. Acid Base: Make a Salt and Water AOH + HB  AB + H2O Example – NaOH + HCl  NaCl + H2O 6. Combustion:Make CO2 and Water CxHy + O2 CO2 + H2O Example – CH4+ 2O2 CO2 + 2H2O

50. Visualizing Equations O H H O H H 2 H2+ 1O2 2H2O