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1B. Looking at Water & Its Contaminants

1B. Looking at Water & Its Contaminants. Learning more about the chemistry of water and how substances interact with water. Do Now:. The teacher has two substances on the desk (A and B). Are they the same? Venture a guess as to what you think they are.

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1B. Looking at Water & Its Contaminants

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  1. 1B. Looking at Water & Its Contaminants Learning more about the chemistry of water and how substances interact with water

  2. Do Now: • The teacher has two substances on the desk (A and B). Are they the same? Venture a guess as to what you think they are. • Explain why beetles have the ability to walk on water. (Take a look at the picture below)

  3. Objectives: • SWBAT: • Learn the physical properties of water & compare to another liquid. • Use a balance • Read a grad. cylinder • Make and record measurements • Record observations 3

  4. Water has Physical Properties • Matter can be distinguished by its properties. • Physical properties are those that can be observed and measured without changing the chemical makeup of the substance • Can you think of some? • Write down at least 3 physical properties of water that you can think of. 4

  5. Physical Properties of water: • Color – colorless, clear • Odor - odorless • Density = mass/ volume • Temperature dependent • Freezing point = 0°C • Boiling point = 100°C • Surface tension

  6. “Pure” Water • “Pure” water is water with absolutely nothing else dissolved or suspended in it • Properties of pure water • Clear • Colorless • Odorless • Tasteless 6

  7. Lab Demo • Make and record proper observations for each demonstration.

  8. Do Now • Draw a graduated cylinder, with the appropriate volume markings and layer the liquids according to density. • 5 mL liquid A, Density = 3.4g/ml • 2 ml liquid B, Density = 0.90/ml • 3 ml liquid C, Density = 1.00g/ml

  9. Do Now • What physical property of water explains the “sheeting action” under the swimmers right arm?

  10. Objectives • SWBAT compare and contrast surface tension between water and alcohol • SWBAT define matter and discuss the physical properties of water. • SWBAT calculate density

  11. Surface Tension

  12. Surface Tension: • Forces of attraction between the hydrogen atoms in water that keep the atoms close together • Almost as if they form a barrier and make the water molecules “stick” together • Held together by cohesive forces. • Responsible for creating a meniscus • Responsible for “spherical” water drops • Doesn’t stick to wax (on cars etc.)Adheres weakly, so molecules stick together.

  13. Molecular view of surface tension

  14. HW • Pg 50 (1-4)

  15. Do Now • Draw: • A) a water molecule (H2O) • B) 2H2O

  16. Objectives • SWBAT identity the number of different compounds in a substance or mixture • SWBAT draw different mixtures and answer questions related to those pictures

  17. Particulate Level To understand the macroscopic (large scale & readily observed) properties of water, you have to understand water’s behavior at the particulate level – the level of small particles – the level of atoms and molecules 17

  18. Substances Atoms – “building blocks of matter” Elements – made of one kind of atom Represented by symbols (H, O, Ne) & sometimes formulas (H2, O2) Molecules – made of atoms joined together – atoms can be the same or different Compounds – made of different elements combined together Represented by formulas (H2O, KCl) 18

  19. MODELS:REPRESENTATIONS OF ATOMS & MOLECULES These pictures are one kind of model (space filling model). 19

  20. Drawing Models • Sample Problem: Draw a model of two gaseous compounds in a homogeneous mixture. • What do you need to know to draw your model? • What is a homogeneous mixture? • What might a gaseous compound look like? • How many compounds are in this mixture? • There is more than one drawing possible. 20

  21. Practice • Describe the picture: • 1. What type of mixture is this? • 2. How many compounds? • 3. What state of matter?

  22. Drawing Models Which of the following drawings best represents a homogeneous mixtures of two gaseous compounds? 22

  23. Drawing Models • Not homogeneous • 2 types of molecules are uniformly mixed • Atoms are colored to represent different elements • 3 different compounds, not 2 The best answer is “b.” “b” & “c” are space-filling models. “a” is a ball-and-stick model. Both are acceptable. 23

  24. Drawing Models Work in pairs on WKST U1B.5- Modeling Matter 24

  25. Do Now • What is a solution? • Describe the difference between a heterogeneous and homogeneous mixture

  26. Objectives • SWBAT review the differences between types of mixtures. • SWBAT create a concept chart of substances and mixtures and provide examples of each. • SWBAT differentiate between symbol, element, compound, and molecule.

  27. Matter • MATTER: IS ANYTHING THAT HAS MASS & OCCUPIES SPACE. • WATER IS MATTER.

  28. MIXTURE PURE SUBSTANCE yes no yes no Is the composition uniform? Can it be chemically decomposed? Colloids Suspensions A. Matter Flowchart MATTER yes no Can it be physically separated? Homogeneous Mixture (solution) Heterogeneous Mixture Compound Element

  29. Substances Dissolve in Water • Aqueous solutions – water based solutions • SOLUTE- substance that is being dissolved • SOLVENT- substance that dissolves the solute (usually water, in aqueous solutions it is water) 29

  30. Solutions All solutions are homogeneous mixtures • A solute dissolves in a solvent to make a solution • Solutions are clear but not necessarily colorless • A conductivity test indicates the presence of dissolved charged particles 30

  31. Substances Dissolve in Water 31

  32. Matter is divided into a mixture or a substance • Substance: • Definite composition, not physically able to separate • Mixture: • two or more substances coming together but keeping their individual properties • “Foul Water” was a mixture of water, used coffee grinds, oil, garlic powder, salt

  33. Types of Mixtures • Homogeneous Mixture: • Composition is the same or uniform throughout • Heterogeneous Mixture: • Composition is not the same or uniform throughout.

  34. 2 Types of Heterogeneous Mixtures Suspension – heterogeneous mixture containing large, solid particles that can settle out or be separated by filtration Colloid – heterogeneous mixture containing particles too small to settle out – cloudy – Tyndall effect 35

  35. Types of Substances • Elements: • One type of atom • Compounds: • Two or more types of atoms chemically bonded together

  36. A. Matter Flowchart • Examples: • graphite • pepper • sugar (sucrose) • paint • soda

  37. A. Matter Flowchart element hetero. mixture compound hetero. mixture solution • Examples: • graphite • pepper • sugar (sucrose) • paint • soda

  38. Homogeneous – Solutions evenly distributed Heterogeneous not evenly distributed Mixtures(variable composition)

  39. Diatomic Elements Hydrogen Nitrogen Oxygen Fluorine Chlorine Bromine Iodine There are 7 diatomic elements These atoms are never alone, if they are the pair up with the same atom

  40. C. Mixtures colloid suspension colloid solution suspension • Examples: • mayonnaise • muddy water • fog • saltwater • Italian salad dressing

  41. Do Now • Fill in table on worksheet Unit1B4,6&9

  42. Objectives • Distinguish between symbols, chemical formulas and equations • Determine the number of protons, electrons and neutrons in an atom

  43. Symbols, Formulas, & Equations • The international language of chemistry includes symbols, formulas, & equations. • Symbols are like letters. • Formulas are like words. • Equations are like sentences. 44

  44. The “letters”Symbols – Elements • Elements are organized on the Periodic Table of Elements • Each element is represented by a symbol • Capital letter • Capital letter & lower case letter • Find some of these symbols on the Periodic Table. 45

  45. The Periodic Table of Elements contains much more useful information than just symbols.You will be learning more about this table throughout this course. People use aluminum to make a variety of products, including foil, cans, & lightweight construction materials. 46

  46. Silicon has properties that lie between those of metals and nonmetals. It is classified as a metalloid. One of its primary uses is in electronic devices. 47

  47. Sulfur is a nonmetal used in products such as fungicides and rubber of automobile tires. 48

  48. The “words”Formulas Formulas represent specific chemical substances. Formulas are made of symbols. Formulas may include subscripts. A subscript refers back to the symbol immediately before it. A “1” is “understood” & not written. 49

  49. Examples • CO • 1 carbon & 1 oxygen • CO2 • 1 carbon & 2 oxygens • NH3 • 1 nitrogen & 3 hydrogens • H2O • 2 hydrogens & 1 oxygen • H2SO4 • 2 hydrogens, 1 sulfur, & 4 oxygens

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