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Chemistry

Chemistry. Unit 1: The Science of Matter E-Cubed Academy . Learning Objective. Understand composition and their impact on the properties of matter Be able to classify chemical vs. physical changes. A Science for All Seasons. What is Chemistry? The study of the composition of matter

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Chemistry

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  1. Chemistry Unit 1: The Science of Matter E-Cubed Academy

  2. Learning Objective • Understand composition and their impact on the properties of matter • Be able to classify chemical vs. physical changes

  3. A Science for All Seasons • What is Chemistry? • The study of the composition of matter • The study of the changes matter undergoes • Why study Chemistry? • Chemistry touches all aspects of life • A basic understanding of chemistry will enable you to make informed and balanced decisions

  4. In your Notes • List at least 5 chemicals that you are familiar with from past experience.

  5. Chemistry • The science that investigates the structure and properties of matter • Matter: anything that takes up space and has mass • Mass: the measure of the amount of matter that an object contains • NOT Matter- • Heat • Light • Radio waves etc.

  6. Matter continued • Structure: refers to what it is made of and of how it is organized • Properties: Describe the characteristics and behavior of matter including the changes it undergoes

  7. Behavior of Matter • Determined by BOTH • The elements it contains • Arrangement of those elements

  8. Example Salt vs. Water Sodium and Chloride Hydrogen and Oxygen Contain different elements --- Have different properties!

  9. Example • Aspirin Vs Table Sugar • Both contain only Carbon, Hydrogen and Oxygen molecules --- same composition • Different Structures Cause Different Behaviors!

  10. Chemistry: Physical Properties • Properties that can be observed without changing the substance • Easily observed or measured • Using five senses BP, MP, color, physical state @ room temperature, odor, electrical conductivity, solubility, magnetism, density, taste, crystal form

  11. Chemistry: Chemical Properties • Those properties of a substance that can only be studied by forming new substances, through a change in composition called a chemical reaction • Describes how something reacts with another substance • how a substance behaves in the presence of another substance • Flammability, reactivity with acid, pH, heat of combustion

  12. Physical change vs. Chemical change

  13. Examples

  14. Let’s look closely at Density • It is an important property of matter • It is used to identify substances • It is also used to separate mixtures Definition of Density: the mass of a specific unit of volume • It is expressed in the following equation; D= m/v or density = mass volume

  15. Example of Density Calculations • If a piece of rock has a mass of 14g and a volume of 5 cm3, what is the density? • Step 1: Write the given and ensure proper units • m =14 g V= 5 cm3 • Step 2: Write the formula • D= m/v • Step 3: Substitute the given into the formula • D = 14g / 5 cm3 • Step 4: solve • D=2.8 g/cm3

  16. Density of Penny • 1982 when the switch happened • After 1982= more shiny • Less dense after 1982

  17. Density • Density is a physical property • Characteristic for a substance • Can be used to identify a substance • How “thick” something is... • D = mass / volume • Units of g/cm3 for solids and g/mL for liquids • Something less dense will float on something more dense

  18. Unit Conversions • Write conversion factors for the following: • 1000 cm3 = 1000 mL • 1 kg = 1000 g • 1 kg = 2.2 lb • 1 L = 1000 mL • How many kg are in 76 g? • How many grams are in 0.53 kg? • How many mL are in 0.439 L?

  19. Answers • 1) .076 kg • 2) 530g • 3) 439 mL

  20. worksheet • Work in groups and complete the problems

  21. Classifying Matter • Substance: matter with constant composition • Element: Made of only one type of atom • Compound: 2 or more elements that are chemically combined • Mixture: Matter with variable composition • Heterogeneous Mixture: Made up of more than 1 phase • Homogeneous Mixture: also called solutions, made up of only 1 phase

  22. Mixtures • A material that is made of 2 or more things which are not combined chemically • Each of the parts still keep their own identities • Made by blending, but NOT forming chemical bonds or chemical change! • Most everyday matter occurs as mixtures

  23. Heterogeneous and Homogeneous Mixtures • A classification of matter based on composition • Homogeneous mixture: no clumping or grouping but rather a uniform dispersal of the material it is made of. • Ex. Air; made of N2, O2, CO2 and other gases • A liquid in which there is a solvent and a solute is called a solution • Heterogeneous mixture: it is easy to identify all if the different components

  24. Matter: Homogeneous and Heterogeneous Mixtures

  25. Homogeneous Mixtures

  26. REMEMBER Mixtures • Are made of 2 or more things which are not combined chemically • Each of the parts still keep their own identities • Made by blending, but NOT forming chemical bonds or chemical change! • Most everyday matter occurs as mixtures

  27. Separating Mixtures • Mixtures can be separated through a physical process, (the identity of the substance remains unchanged). • Using their Physical properties • Bringing about physical changes to separate the mixture into its components (different substances it is made of)

  28. Making a Mixture AND SAND SUGAR

  29. The Mixture

  30. How can we separate it? • What do you think? • Work with your lab partner to come up with a suggested method. (10 minutes) • You may use your class notes, but your brain is your best asset. • Write your thoughts in your notebooks. • Do not be afraid to try!

  31. Report out on ideas • So, what did you come up with? • Share your thoughts! (10 minutes)

  32. What can we do? Method #1 Use a pair of tweezers and a microscope to physically separate the particles Requires a lot of time and patience

  33. Method #2 Step #1 Recall the properties of water and of sand Sugar dissolves in water Sand does NOT Use the difference!

  34. Step #2 Recall the properties again sand will not pass through a filter Sugar and water solution will Use the difference!

  35. Step #3 Recall the properties of sugar and water sugar will not evaporate (change state) at 100 degrees Celsius water will ! Use the difference! Step #4

  36. You have the two pure substances again! • Sand in the filter! • Sugar in the bottom of the beaker!

  37. Lab Tomorrow • Separating Mixtures

  38. REMEMBER: Physical Properties • Density: Mass per unit volume • Solubility in water : Does it dissolve in water? • State of mater: at room temp and pressure • Transparency: lets light pass through • Boiling point: Temperature at which a substance goes from liquid to gas • Melting point: Temperature at which a substance goes from solid to a liquid • Brittleness: Tendency to crack or break • Ductility: Ability to bend without breaking • Elasticity: Ability to be stretched or compressed then return to original size

  39. Chemical properties • Chemical Property • Flammability: The ability to burn • Ability to rust:Reacts with oxygen to produce rust • Reactivity with vinegar: Reacts with vinegar to produce new substances

  40. Solutions (homogeneous) • Air (gas) • Martini (liquid) • Salt water (liquid) • Plastic (solid)

  41. Substances • Homogeneous materials that contain only 1 kind of matter • Have definite composition and properties • Substances which can not be broken down into a simpler substance is an ELEMENT. • Substances which can be broken down into a simpler substance is a COMPOUND. • They are made of 2 or more elements

  42. Elements • Made of only one kind of atom • Can not be made simplified by physical or chemical means • Can exist as atoms (carbon) or molecules (N2)

  43. Compounds • Consist of 2 or more DIFFERENT atoms bound together (H2O) • Can be broken down into smaller types of matter by chemical means only. • Have properties which are different than the elements they are made of • Always contain the same ratio of its components atoms ( ex 2 hydrogen's to 1 oxygen, in water)

  44. Elements, Compounds, Mixtures • Sodium is an element. • Chlorine is an element. • When sodium and chlorine bond they make the compound sodium chloride, commonly known as table salt. Compounds have different properties than the elements that make them up. Table salt has different properties than sodium, an explosive metal, and chlorine, a poisonous gas.

  45. Classify the Following • Ocean water- • Calcium- • Vitamin C- • Dry ice – • Copper- • Grain alcohol- • after shave lotion- • Hamburger- • Al foil – • Milk- • Salt- • Iron nail-

  46. Answers • Ocean water- solution • Calcium- element • Vitamin C- Compound ( L-asorbic acid) • Dry ice – compound (CO2) • Copper- element • Grain alcohol- compound (C2H5OH) • after shave lotion- heterogenous mixture • Hamburger- hetero • Al foil – element • Milk- solution • Salt- cmpd • Iron nail- element

  47. Mixtures vs. Pure substances • Mixtures can be separated based physical properties and through physical change • Pure substances can only be separated through chemical changes • Separated from compounds into elements • H2O- H and O2 • Made into compounds from elements • H + O  H2O

  48. Chemical Change and Energy • All chemical changes involve some sort of energy change! • Many chemical changes (reactions) releaseenergy • Exothermic reactions: release energy as heat • Some reactions absorb energy • Endothermic reactions: absorb heat energy

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