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Announcements

Announcements. Textbook/clickers Homework Lab Next week Chemistry Help Center Attendance Sheets. Chapter 1: Matter and Measurement. Atoms and Elements Molecules and Compounds Classification of Matter Properties of Matter and Measurement Temperature Mass Volume

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Announcements

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  1. Announcements Textbook/clickers Homework Lab Next week Chemistry Help Center Attendance Sheets

  2. Chapter 1: Matter and Measurement • Atoms and Elements • Molecules and Compounds • Classification of Matter • Properties of Matter and Measurement • Temperature • Mass • Volume • Unit Analysis Calculations

  3. The Periodic Table- It’s 140 This Year!

  4. ATOM Smallest unit of matter ELEMENT Contains only 1 type of atom MOLECULE Contains >1 atom connected together COMPOUND Contains >1 atom connected together AND >1 type of element Pure Substances=Elements and Compounds

  5. Classification of Matter

  6. Clicker Question 1 • Which of the following is a pure substance? • Grain alcohol • Sparkling water • 14-carat gold • Chocolate chip

  7. Clicker Question 2 • What is a root beer float? • Compound • Element • Homogeneous Mixture • Heterogeneous Mixture

  8. Let’s ponder the Root Beer Float some more… • Root beer float deconstructed* • Ice cream • Sugar • Cream • Vanilla • Root beer • Carbonated water • Water • Carbon Dioxide • Sugar • Root extracts (sassafras, sarsparilla root, liquorice, anise, etc.) *An homage to a great book, Twinkie Deconstructed, by Steve Ettlinger

  9. Chapter 2: Modern Atomic Theory • Matter consists of atoms • Atoms consist of three fundamental particles, found in the nucleus and the space around the nucleus

  10. Chapter 2- Elements and Compounds • Modern atomic theory • All matter is composed of small particles called atoms • Atoms are made up of three subatomic particles

  11. Arrangement of Particles in the Atom • Small nucleus contains nucleons: • Positively charged protons • Neutrons with no charge • Vast majority of mass • Outside the nucleus • Negatively charged electrons • Large volume of (mostly empty) space relative to nucleus

  12. Atoms • All atoms of an element have the same atomic number = number of protons • In a neutral atom (no charge), the number of positively and negatively charged particles must be equal # protons = # electrons • The mass number= protons + neutrons

  13. Isotopes • IsotopesAtoms with same number of protons but different number of neutrons

  14. 90 35 Mo Cl 42 17 Isotopes • When two atoms have the same atomic number (Z), but different atomic masses (A), they are called isotopes • Isotopes differ in the number of neutrons • ATOM SYMBOLS 17 protons 35-17=18 neutrons • EXAMPLE: How many neutrons does Molybdenum-90 have? # protons=42 # neutrons= 90-42=48 mass number→A X atomic number→Z

  15. Isotopes • Most elements have multiple isotopes • 1H, 2H (deuterium), 3H (tritium, radioactive) • 79Br, 81Br • 64Zn, 66Zn, 67Zn, 68Zn, 70Zn • Atomic mass is the mass of a single atom • Average atomic mass takes into account isotopes and natural abundance • We use atomic mass units (u) 1 amu = 1u = 1.661 x 10–24 g(about the mass of a proton)

  16. It’s Time For Some Donut Math! • Dunkin Donuts sells both regular-sized donuts and Munchkins • Let’s say that of all the donuts sold: • 78.3% are regular-sized (mass= 57g) • 21.7% are Munchkins (mass= 10g) • What is the weighted average mass of a Dunkin Donut?

  17. Isotopes and Average Atomic Mass A Non-Edible Example Chlorine has two isotopes: What is the average atomic mass of Chlorine?

  18. What do these things have in common? Hormones!

  19. epitestosterone testosterone Floyd Landis Case • Landis won 2006 Tour de France • Tested positive for testosterone doping • Does Landis have an high testosterone level?

  20. Floyd Landis Case • Is the excess testosterone natural or synthetic? • Isotope-ratio mass spectrometry (CIR) used to determine the ratio of 13C to 12C in Landis’ testosterone • Photosynthesis prefers 12C • C3 plants: Strong preference for 12C • C4 plants: Less of a preference for 12C • Normal diet= mixture of C3 and C4 plants • Synthetic testosterone comes from soy, contains less 13C • 13C:12C reduced  Landis positive for doping

  21. What do these things have in common? Hormones!

  22. What holds an atom together? Coulomb’s Law of electrostatic interactions. General Behavior: Like charges repel. Opposite charges attract.

  23. What holds an atom together? Coulomb’s Law of electrostatic interactions. • If we double a charge from +1 to +2, the force will: • Double • Halve • Quadruple • Quarter

  24. What holds an atom together? Coulomb’s Law of electrostatic interactions. • If we double the distance, the force will: • Double • Halve • Quadruple • Quarter

  25. What’s wrong with this picture? Electrons are held near the nucleus by the electrostatic attraction between them, but … The forces of nature:

  26. We’re not just making it up! How could we possibly know that the nucleus is small compared to the size of the atom? Why not think the protons, electrons and neutrons are all mixed together? The Rutherford Experiment

  27. We’re not just making it up! The Rutherford Experiment

  28. We’re not just making it up! The Rutherford Experiment

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