Chemical Reaction: another name for a chemical change; a change in which 1 or more substances are converted into new substances

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2 Chemical Reaction: another name for a chemical change; a change in which 1 or more substances are converted into new substances A + B à AB AB à A + B Absorb or release Energy

3 CHEMICAL REACTION No change to nucleus No new atoms/elements created (No transmutation) Bonds formed or broken NUCLEAR REACTION Nucleus changes Transmutation (new atoms/elements created) No bonds involved

4 Chemical bond: force that holds atoms together in a compound Bonds form when valence electrons move between 2 atoms Electrons can be transferred from 1 atom to another OR shared between them Chemical reactions occur when bonds are formed/broken

5 COVALENT BONDS A bond that forms when atoms share 1 or more pairs of electrons Nonmetal nonmetal Covalent compound can have equal sharing (O=O) or unequal sharing (H 2 O) Unequal sharing causes partially δ+ or δ parts of molecule IONIC BONDS A bond formed between oppositely charged ions (charged particles) Metal Nonmetal Ionic compound has a + end and a end, but the overall charge of the compound is neutral

6 Symbol: 1 or 2 letter set of characters used to identify an element Na, C, F Chemical formula: Combination of symbols that represent the elements in a compound Examples: NaCl, CO 2 Subscripts: Show the # of atoms of an element in a molecule OR the ratio of elements in a compound No subscript = 1 A chemical equation is a shorter, easier way to show chemical reactions using symbols instead of words 2H 2 + O 2 à 2H 2 O

7 Reactants: substances that react Left hand side of equation Products: new substances that are produced Right Hand side of equation à yields (s), (l), (g), (aq) indicates phase

8 No matter how many reactants and products, all atoms at the start will be there at the end H 2 + O 2 à H 2 O 2 2 H and 2 O on both sides of the equation The amount of matter in a chemical reaction doesn t change. The total mass of the reactants must equal the total mass of the products Conservation of mass!!! Ex:.5g H g O 2 à 16.5g H 2 O 2.5g + 16g = 16.5g

9 1. Look at the formulas 2. Count the # of atoms of each element on each side of the equation 3. DO NOT add or change subscripts That would change the compound!! 4. Use a coefficient a # placed on front of a chemical formula in the equation Indicates multiple molecules Ex: 2H 2 represents 2 molecules of H 2 Coefficients get multiplied by subscripts 3H 2 represents 6 atoms of H

10 Example: H 2 + O 2 à H 2 O H=2, O=2 H=2, O=1 H 2 + O 2 à 2H 2 O H=2, O=2 H=4, O=2 2H 2 + O 2 2H 2 O H=4, O=2 H=4, O=2

11 5 categories Combustion (burning) Synthesis Decomposition Single Displacement Double Displacement

12 Must occur in the presence of Oxygen Produces CO 2 and H 2 O Ex.) CH 4 + 2O 2 à CO 2 + 2H 2 O

13 2 or more substances combine to make a more complex substance A + B à AB 2H 2 + O 2 2H 2 O In the cartoon, the skinny bird (reactant) and the worm (reactant) combine to make one product, a fat bird

14 1 or more reactants break down into simpler products AB à A + B 2H 2 O à 2H 2 + O 2 (Electrolysis of Water) In this cartoon the egg (the reactant), which contained the turtle at one time, now has opened and the turtle (product) and egg shell (product) are now two separate substances

15 Sometimes called Single Replacement When 1 element replaces another in a compound AB + C à AC + B Cu + 2AgNO 3 Cu(NO 3 ) 2 + 2Ag The guy in the orange shirt steals the date of the other guy. So, a part of one of the reactants trades places and is in a different place among the products

16 Also called Double Replacement When 2 elements in different compounds trade places AB + CD à AD + CB Ba(NO 3 ) 2 + K 2 SO 4 à BaSO 4 + 2KNO 3 In the cartoon, the two men trade hats

17 Every chemical reaction involves a change of energy Some reactions release energy and others absorb energy All chemical reactions need energy to get started Activation Energy: the minimum amount of energy needed to start a chemical reaction Sulfur reacting to heat

18 EXOTHERMIC A reaction that releases energy in the form of heat Products have less stored Energy than the reactants Endothermic A reaction that absorbs energy Products have more stored Energy than the reactants

19 1. Precipitate a solid that forms from a solution during a chemical reaction. 2. Color change 3. Gas production 4. Changes in Temperature 5. Changes in properties 6. Production of new materials that are chemically different from the starting materials Sulfuric Acid & Sugar

20 Depends on how easily the particles of the reactants can get together Affected by: Concentration Surface Area Temperature Catalysts makes a reaction happen faster by lowering the activation energy Inhibitors used to decrease the rate of a reaction

21 Covalently bonded Always contain Carbon Usually contain Hydrogen Examples: Sugarless gum Aspirin Sorbitol Aspartame

22 When a compound is made of only carbon and hydrogen atoms Example: Methane simplest CH 4 Carbon atoms have 4 valence electrons to bond. Form C- H bonds Carbon atoms can share 2 or 3 of its electrons to form double and triple bonds Never more than 4 bonds

23 Hydrocarbons that have only single covalent bonds Methane : CH 4 Ethane: C 2 H 6 Can have C- H and C- C bonds Can line up or branch or form rings

24 Hydrocarbons with at least one double covalent bond between C atoms Ethene Propene

25 Organic compounds made of Carbon, Hydrogen, and Oxygen Have a hydroxyl group OH Examples: Methanol and ethanol

26 Large organic molecules made of many smaller bonded units Example: polyethylene Original molecule is a monomer Some polymers are natural or man made Natural: rubber, wood, starch, protein, DNA Man- made: Plastics, fibers

27 Determined by structure Long thin chains, like spaghetti are tangled but can slide over each other Example: milk jugs Cross linked chains: Become more elastic and stretch (volleyball net) Example: rubber bands

28 Additives can modify surface properties such as preventing the sticking of polymers to machinery Polymer additives can be reinforcing fillers which increase the strength properties of the polymer Two forms: fibrous and granular or powder. Carbon black is an inorganic powder which is used to reinforce natural and synthetic rubber

29 Recycled by numerical codes 1 and 2 widely accepted 3 and 6 are not accepted because too rigid to break down and too expensive Polyethylene terephthalate (soda bottles, car parts, clothing) High density polyethylene (Milk, bleach, toys, grocery bags)

30 PET Backpacks, sleeping bags, carpet, new bottles, clothing HDPE Furniture, toys, trash cans, picnic tables, fences PVC Used in vinyl siding, cooking oil bottles, car parts recycled into: toys and playground equipment Polystyrene fast food containers, toys, plastic utensils, drinking cups, CD cases recycled into: insulated clothing, egg cartons, thermal insulation

31 Naturally occurring organic compounds that are very important to living things Examples: Carbohydrates, Proteins, DNA Proteins are polymers of amino acids. Long chains of amino acids Amino acid: Any 1 of 20 different naturally occurring organic molecules that arrange to form proteins Made of C, H, S, N, and O The way they combine determines which protein is made

32 A polymer with a complex structure Contains: C, H, N, P and O Forms in paired chains or strands Double Helix Attached are 4 possible monomers: adenine, thymine, cytosine and guanine