Why Take “Chemistry”?

1. Why Take “Chemistry”? • Guidance 2. Career 3. How does the world work? Sweat Computers Atomic bombs Fireworks Ice skating Water bugs Fossil fuels Acid rain Why doesn’t a gas tank explode?

2. Remsen’s study of nitric acid • Jot down your observations Chemistry What is it?

3. Ira Remsen’s Experiment • Penny + nitric acid observations:

4. OBS. HYP. EXP. THEO. • Observation • (not inference) Scientific Method • a logical way to study problems OBS. the solution turned blue

5. OBS. HYP. EXP. THEO. • Hypothesis: a proposed explanation for the observation that can be tested.  The copper in the penny changed to produce the blue color.

6. OBS. HYP. EXP. THEO. • Experiment: a means to test the hypothesis.  Try the same reaction using silver metal instead of a copper penny.

7. OBS. HYP. EXP. THEO. HYPOTHESIS EXPERIMENT

8. OBS. HYP. EXP. THEO. • Theory: an explanation of why experiments give certain results. • broad in scope • predictive • can never be proven

9. What is a model? Model of the atom Cu + 4H+ +2NO3- Cu2+ + 2NO2+ 2H2O Theory Model Remen’s experiment:

10. Not a Bunch of Facts Patterns !

11. Chemistry Student definitions. • Chemistry: study of the • composition of substances & • changes substances undergo.

12. Chemistry in the Real World Everything is a chemical !!!

13. Chemistry: Brief History • B.C.: Some Greeks thought: • Matter made of particles (atoms) vs. continuous • Based on pure logic, rather than experimental

14. Middle Ages: Alchemists

15. Modern Concepts 1700’s Antoine Lavoisier: • father of modern chemistry • “laboratory” • excerpt • 1800’s Dalton • atomic theory based on data • 1850’s Mendeleev • Periodic Table

16. MATTER? Matter • Anything that takes up space and has mass. aluminum light water temperature airheat

17. Matter The amount of matter is measured by MASS not volume or weight. (water vs. air)

18. Classification of Matter

19. Types of Matter • 1.Substance (“pure substance”) • Matter with uniform and definite composition. • Every sample has exactly the same properties. example: water

20. Two Types of Pure Substances Element- simplest form of matter that can exist in the lab. e.g. C, H, etc (Periodic Table) Compound- contains 2 or more differentelements bonded together; it can be broken into simpler substances “chemically.” e.g. water, salt (NaCl), sugar

21. heat Carbon: C element Water: H2O compound + electrical energy Hydrogen: H2 element Oxygen: O2 element + Sugar: C6H12O6 compound

22. Element vs. Compound? • Classify: • Water: H2O • Vinegar: HC2H3O2 • Oxygen: O2 • Ozone: O3

23. Types of Matter • 2. Mixtures • two or more different substances mixed together • proportions can be varied • (e.g. 20% salt in water vs. • 30% salt in water) • each substance retains its original properties

24. Mixtures: Two Types 1. Homogeneous mixture • mixture with uniform composition throughout • mixed at the “molecular level” • often transparent, not cloudy • synonym is “solution.” e.g. salt water, steel

25. Mixtures: Two Types • 2. Heterogeneous mixture • mixture that does not have uniform composition • often see small chunks or pieces of different substances • often cloudy e.g. soil Italian salad dressing

26. Substance, Homogeneous or Heterogeneous Mixture ?

27. Mixtures can be separated by physical means • chromatography (demo) • distillation (next slide) • magnetism (lab) • filtration (lab) • density

28. Distillation

29. physically separable chemically separable Classification of Matter Kool-aidcement wateroxygen

30. Ice Water Steam States of Matter How many? •4 states of matter!

31. Changing States of Matter (Temp. is a measure of the average kinetic energy of the molecules that make up the substance.) Raise Temperature

32. Physical Property Quality that can be observed without changing the substance’s composition.

33. Physical Change A change that does not alter the substance’s composition. e.g. boiling water, cutting paper

34. Chemical Property Ability of a substance to undergo a chemical reaction and form a new substance. Reactants  products e.g. iron + sulfur  iron(II) sulfide (NOT simply mixing iron + sulfur) Demo

35. Chemical or Physical ?? • dry ice evaporates • a car fender rusts • pepper is ground-up in a pepper mill • bread goes stale • water freezes • you file your nails • you take an antacid tablet

36. Conservation of Mass & Energy In any process or reaction, both mass and energy are conserved. • e.g. burn coal: • where does the mass go? • where does the heat energy come from?

37. Study Guide

38. Elements Write the name or symbol: fluorine zinc neon chromium manganese I U Ni Ag Fe

39. Warm-up Define “chemistry”

40. Warm-up When water boils, it gives off air bubbles. Is this statement an observation?

41. Warm-up Explain the difference between a homogeneous mixture and heterogeneous mixture. • Mud? • Kool Aid? • Milk?

42. Warm-up Super-fun element quiz! Argon Strontium Scandium Mercury Pb I Ne Mg

43. Warm-up How many states of matter are there? Which state has a constant volume and takes the shape of its container?

44. Warm-up Which state of matter has definite volume and takes the shape of its container? Define “temperature.”