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Unit 3

Unit 3. Chemistry. What is it?. What it isn’t:. MATTER. Examples. Properties. Create these two diagrams on a new piece of loose leaf in your binder. What is it?. Examples. CHANGE. Types. How can you tell it occurred?.

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Unit 3

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  1. Unit 3 Chemistry

  2. What is it? What it isn’t: MATTER Examples Properties • Create these two diagrams on a new piece of loose leaf in your binder. What is it? Examples CHANGE Types How can you tell it occurred?

  3. As you observe the following demonstrations, record observations in the previously constructed diagrams

  4. What is Science? • Science is the systematic study of the observable world • What makes science different than other areas of human activity is that science can never be absolutely proven true, it can only be proved false by experiment • Question: So what does that mean? • Answer: Science is always changing

  5. Why do we study Science? • Science brought us many of the innovations we use today • Artificial fibers for clothing and carpet, computers and iPods, cars, television, YouTube.com, etc. • Science has enabled mankind to treat terrible diseases, and prevent pain and suffering • Chemistry has enabled us to feed our ever growing population

  6. Bad Science • When common people don’t know much about science it becomes arcane (‘magic’!); the few people who do know about science abuse it. • BAD SCIENCE: Chemical and Biological Weapons, science to support racism (called eugenics), science against homosexuality or against women • Your science education should enable you to process media in the future, and better understand the world and how to live in it • How do we prevent the misuse of science? • By being educated! As future voters, you affect policy of government and can change the world for the better by making good decisions regarding science. You can also keep your family safer and healthier with some knowledge of science. Science is power!

  7. Q: What is Matter? • A: any substance that has mass and occupies space (meaning it has a volume) • Q: What is change? • A: cause a substance to be transformed into another substance with different observable properties

  8. Properties of Matter • A Physical Property is a characteristic of a substance that may help identify it • Colour, Texture, Odour, Lustre, Clarity, Taste are familiar properties • Hardness: measure of the resistance of a substance to being scratched or dented • Malleability: substance be hammered or bent into other shapes • Ductility: can be pulled or stretched into wires • Melting and Boiling Points • Solubility: The ability of a substance to be dissolved in a solvent such as water • Viscosity: measure of how easily a liquid substance flows • Density: amount of matter in a given unit of volume

  9. Describe the following items using each of the physical properties: • A penny • Vinegar • Chalk

  10. A Chemical Property describes the behaviour of a substance as it becomes a new substance • Combustibility: ability of a substance to react with oxygen and release a great deal of energy when exposed to ignition • Reaction with Acid: during contact, the substance reacts with acid creating heat and gas

  11. Questions • What property is described in the following statements: • Copper metal can be bent into many shapes • A steel blade can scratch glass • A nickel coin is shiny • Create a chart that splits all the physical properties into two groups: • Observed using Senses • Observed by doing tests

  12. Change • A Physical Change occurs when the substance is unchanged at the molecular level, but changes state or form • Ex. water freezes • A Chemical Change occurs when the original substance is transformed into one or more different substances that have different properties • Ex. liquid gasoline is burned and produces carbon dioxide and water

  13. How can you tell them apart? • There are some key indicators of chemical change; one or more of these indicators means the reaction was chemical • A new colour appears • Heat or light is given off • Bubbles of gas are produced • A solid material called a precipitate is formed • The change is difficult to reverse

  14. Questions • Classify the following as Physical or Chemical changes • Garbage rotting • Cutting carrots • Silver spoon turns black • Boiling an egg • Boiling water

  15. Elements & Compounds • Particle Theory: Arose about 2000 years ago in Greece, a philosopher named Democritus suggested that all matter is made of tiny particles to small to be seen • He suggested that there was a limit to how small an object could be divided • The term atom was coined, which means “indivisible”

  16. Particle theory includes the following postulates (similar to word ‘assumptions’) • All matter is made of tiny particles. • All particles of one substance are identical; different substances are made of different particles. • The particles are always moving. The more energy they have, the faster they move. • There are attractive forces between the particles; these forces are stronger when the particles are closer together

  17. An element is a pure substance that cannot be broken down any further; similar to an alphabet, the different types of elements can be found on the periodic table • A compound is a pure substance composed of two or more elements bonded together in a fixed ratio • Do not get the following words confused: • Atom (single particle) is related to the wordMolecule (2 or more particles bonded together) • Element (specific type of atom) is related to the word Compound (combination of specific types of atoms)

  18. A pure substance is a substance that consists of a single type of particle • A mixture contains two or more types of particles • There are two general types of mixtures: • Solution: Appears to be one pure substance • i.e. sugar and water • a.k.a homogeneous mixture • Heterogeneous Mixture: There are visible parts to mixture • i.e. sand and water

  19. Atoms join together in combinations by forming bonds, creating a molecule • Using our periodic table, we can create a series of rules for how molecules bond • Need periodic table • We use chemical symbols to represent each atom; the periodic table is the tool necessary to put a name to each symbol • Q: How is the periodic table organized? • A: It is organized according to Atomic Number

  20. Identify the symbols of the following elements in your notebook: • Carbon • Oxygen • Chlorine • Tungsten • Palladium • Nickel • Copper • Iron • Silver • Hydrogen

  21. Types of Elements • The ‘staircase’ is a region on the periodic table that serves as a border, separating the metals on the periodic table from the non-metals • Some elements touching the staircase are called metalloids or semi-metals, because they seem to be a combination of both • Create a sketch of the periodic table in your notebook, locate the staircase • All elements to the left of the staircase are metals, all elements to the right of the staircase are non-metals • Semi-metals include: Boron, Silicon, Germanium, Arsenic, Antimony, Tellurium, Polonium

  22. Indicate whether each of the following elements are metals or non-metals • Potassium • Calcium • Aluminum • Sulfur • Krypton • Uranium • Barium • Iodine

  23. Bonding • Draw a labeled diagram of an atom in your notebook including the following: • Nucleus, electron, proton, neutron • Q: Which part of the atom is most likely to make contact with another atom and form a bond? • A: the outermost electrons

  24. The outermost electrons are called valence electrons • For Group A Elements, the Group number indicates the number of valence electrons; indicate the number of valence electrons next to each element: • Li • Be • B • C • N • O • F • Ne

  25. Bohr-Rutherford Diagrams • Electrons occupy distinct energy levels called Quanta • A Bohr-Rutherford Diagram shows an arrangement of electrons in different orbits around a nucleus; it follows these rules: • The nucleus is a circle in the center of the diagram; inside the circle is the number of protons (p+) and neutrons (no) • The first ring around the nucleus represent the first energy level; it can hold a maximum of 2 electrons • The second ring is drawn after the first ring is filled; it can hold a maximum of 8 electrons • The third ring is drawn after the 1st and 2nd rings are filled; it can hold a maximum of 8 electrons • The fourth ring is drawn after the first 3 are filled; it can hold a maximum of 18 electrons

  26. After drawing the nucleus, indicate in a space off to the side of your diagram the number of electrons in the atom (same as atomic #) • Begin filling the first ring by drawing dots on the ring; after 2 electrons, draw the next ring and fill, and so on.

  27. p+=6 no=6 Example • Carbon: Atomic# = 6 • Atomic Mass = ~12 (round to whole number) • p+=6 ; e-=6 • no=6  Atomic Mass – Atomic# = # of neutrons

  28. Q: How many outermost electrons are in this diagram? • A: 4 • When you draw your Bohr-Rutherford Diagrams, be sure to check your answer by comparing the number of valence electrons in your diagram to the number that should exist according to their group number

  29. Assignment • Draw the Bohr-Rutherford Diagram of the first 10 elements in the periodic table in your notebook.

  30. Atoms in their natural state have incomplete outer shells • Atoms will form bonds by exchanging electrons in order to have a complete outer shell. • Atoms will either want to gain electrons to complete their outermost shell, or lose electrons to abandon their outermost shell for their most complete interior one

  31. Assignment • Look back at the previous 10 Bohr Diagrams, and state how many electrons the atom would have to either gain or lose to have a complete outermost shell. • Circle the one you believe is easier to achieve • Q: Which group of elements doesn’t gain or lose electrons? Why do you suppose these are called the “Noble Gases” • A: Group 8A; these elements are already complete and will not exchange electrons, meaning they will not form bonds • Q: Carbon and other group 4A elements tend to not form ions, why do you suppose that is? • A: it has to either gain or lose 4 electrons, very difficult to achieve in either direction

  32. Fill in the following chart for the first 10 elements:

  33. Hints: • Electrons are negatively charged, so if an atom gained 3 electrons it has a charge of -3; conversely if an atom lose 2 electrons it has a charge of +2 • Each electron exchanged represents a bond

  34. Bonding Lab • Do not keep the pink sheets; please return them at the bell; complete all work on a new piece of paper. • This lab will use model kits • two students to a kit • Must complete on lab benches (flat surface) • Do not leave near the edge • When complete, please return all parts to the box so they don’t walk away • If you drop a piece, secure the remaining pieces in the box and quickly collect the dropped piece • If you are missing any pieces, please as for assistance

  35. Name, Partner, Date, Title, Kit # • Record your findings for each lettered step of the procedure • Answer all questions

  36. Names and Formulas for Compounds • How Elements Combine: • Metals combine with nonmetals in many compounds • Write the name of the metal first, and the non-metal second • Change the ending of the nonmetal to “-ide” • Each type of atom has its own unique bonding capacity • Atoms combine so that each can fill its combining capacity

  37. Writing Names • Using each of elements listed below, write the name of the compound they would form according to these rules: • Aluminum and Oxygen • Lithium and Hydrogen • Calcium and Sulfur • Answers: • Aluminum Oxide • Lithium Hydride • Calcium Sulfide

  38. Combining capacity is the number of connections an atom must make to form a compound • Elements combine in order to become more stable, the result of bonding is that all valence shell electrons are filled and complete • Some metals have more than one combining capacity (B Group Transition Metals); these will be discussed later

  39. The relationships between group number and bonding capacity is:

  40. Na Cl • Imagine that each combining capacity corresponds to a ‘hook’, and each atom represent a ‘ball’; we call this a hook-and-ball diagram • Q: Sodium and Chlorine combine to form the compound Sodium Chloride; Draw a hook-and-ball diagram and write the formula. Formula: NaCl

  41. Br Ca Br • Calcium has a combining capacity of 2, which corresponds to 2 hooks • Bromine has a combining capacity of 1, which corresponds to 1 hook • Because Calcium needs to form two bonds, but a single Bromine can form only one bond, a second Bromine is required • The Formula for Calcium Bromide is CaBr2

  42. Assignment • Create ball-and-hook diagrams for the following combination of elements; write the name of the compound and the formula: • Lithium and Iodine • Beryllium and Oxygen • Calcium and Chlorine • Aluminum and Oxygen • Aluminum and Nitrogen

  43. Rules for Writing Formula • When writing a formula, we write the symbol for the metal first, then the symbol for the non-metal second • i.e. Aluminum Oxide = AlO • The number of atoms of each are indicated with a small number in subscript • i.e. Al2O3 • General Formula: • X# of XY# of Y

  44. Transition Metals • Often, transition metals will have more than one combining capacity • We use Roman Numerals to identify the combining capacity of a transition metal • Some common Roman Numerals are: • I = 1 • II = 2 • III = 3 • IV = 4 • V = 5 • VI = 6

  45. Copper has combining capacity of 1 or 2, meaning that copper can form two types of compounds with oxygen: • Copper (I) oxide • Copper (II) oxide • Draw a ball-and-hook diagram for each of these compounds, and write out the formula for each

  46. Assignment • Create ball-and-hook diagrams for the following combinations of elements; write the formula of the compound • Iron (III) Chloride • Lead (IV) Oxide • Tin (II) Bromide

  47. Key Concepts in Chemistry • Nature of Science • Properties of Matter • Nature of Change • Particle Theory of Matter • Periodic Table of Elements • Bohr Rutherford Diagrams • Writing Structural Formulas, Formulae and Names

  48. Review Assignment • Create a Quiz and Answer Key that meets the following criteria: • A True/False Section (5 questions) • A Multiple Choice Section (4 Questions) • A Short Answer Section (4 Questions) • A Diagram Section • Bohr Rutherford (3) • Ball-and-Hook, including name and formula (4) • Include a transition metal • A Structural Diagram Section (3 questions)

  49. Evaluation • Due Date: • Tuesday, May 5th • Quiz • 23 marks  full marks if you meet the criteria and questions are at an appropriate level • Answer Key • 10 marks  Each question has a correct answer recorded on a separate sheet of paper • Bonus • 10 marksTrade quizzes with a partner and complete. Correct your partners quiz and return it to them. If you have a corrected quiz from another student you will receive bonus credit (to a maximum of 33/33) ; repeat as necessary, time permitting

  50. Chemistry Unit Exam • Date: Friday, May 8th • Open-book • Covers material from our element study through to last slide • Key Areas: • Terminology: Atomic Number, Atomic Mass, etc. • Calculation: # of Neutrons • B.R. Diagrams • Ball-and-hook Diagrams • Naming Compounds; Writing Formula • Trends in the Periodic Table • Format: Same as Quiz

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