UNIT 1 – MATTER AND QUALITATIVE ANALYSIS

1. UNIT 1 – MATTER AND QUALITATIVE ANALYSIS

2. OBJECTIVES • To understand the difference between observation and inference • To understand the difference between theoretical and empirical knowledge • To explain the development of the atomic model • To describe the relationship between atomic number, atomic mass, and the different subatomic particles • To relate observations and inferences and describe real world examples

3. Building Scientific Knowledge • Observation and Inference • Observation: Statement that is based on what you see, hear, taste, touch and smell • Inference: A judgment or opinion that is based on observations and/or conclusions • Integral part of qualitative analysis • When trying to identity matter, scientists firs observed the sample, then they infer based on their observations and comparing to known matter

4. TASK: THE BURNING CANDLE • Materials: Candle, match, ruler, timer • Obtain a candle, match and watch glass • Light the candle ad drip some wax on the watch glass. Place the candle upright in the hot wax and secure it. • Observe the candle for 5 minutes • Write down as many statements as possible about the burning candle • Divide the statements into two categories: observations and inferences • Compare the number of observations to the number of inferences

5. Extension • Provide ONE example of an observation and ONE example of an inference that could be stated by each of the following: • A nurse examining a patient with a high fever • A chef tasting a new recipe • A paramedic arriving at the scene of an accident • A firefighter sifting through the debris of a recently extinguished fire

6. Empirical and Theoretical Knowledge • Empirical Knowledge: knowledge coming directly from observations • Theoretical Knowledge: knowledge based on ideas that are created explain observations • Theory: an explanation of a large number of related observations

7. Models • Model: representation of a theoretical concept • Help to visualize a theory and suggest ways to test the theory

8. Homework • Page 12: #1-3

9. Early Atomic Models (Text Ref. 1.3) • Atom: the smallest particle on an element that has all the chemical properties

10. Dalton’s Atomic Theory (1803) • All matter consists of definite particles called atoms • Each element is made up of its own type of atom • Atoms of different elements have different properties • Atoms of two or more elements can combine in constant ratios to form new substances • Atoms cannot be created, destroyed or subdivided in a chemical change

11. Dalton’s Model (Billiard Balls)

12. Subatomic Particles - Electrons • 1897: J. J. Thomson used cathode ray tubes to examine gas discharge • Observed: All gases emitted beams that behaved the same under magnets • Inferred: There must be particles within all atoms that are the same and are negatively charged • Later: names electrons

13. Thomson’s Model • “The Raisin Bun” model: • + and – charges are mixed together • Gave us electrons: Electrons are negatively charged • Atoms can gain or lose electrons to form ions

14. Rutherford’s Experiment

15. Anticipated: Actual:

16. Rutherford’s Model Electrons Protons Neutrons

17. Explanation • The atom is made of a dense core (nucleus) with positively charged protons and neutral neutrons • Electrons orbit around the nucleus • The number of protons determines the element’s identity • The number of electrons equals the number of protons in NEUTRAL elements

18. Isotopes • Elements with the same number of protons but a different number of neutrons are called isotopes • Masses are averaged on most periodic tables • Example: Carbon • 6 proton; 6 electrons • Most carbon atoms have 6 neutrons: Carbon-12 • Some have 7 neutrons: Carbon-13 • Some have 8 neutrons: Carbon-14

19. SUMMARY OF SUB-ATOMIC PARTICLES

20. The Periodic Table: An Introduction • The Periodic Table is an incredibly useful tool that organizes all known elements into columns and rows according to their chemical and physical properties • Elements 1-92: Elements that are found naturally on earth (except 43) • Elements 93-117: Not stable, made in particle accelerators • Group: columns • Period: rows • Metals are on the right; Non-metals are on the left; Metalloids are on the jagged line going down the left hand side

21. Some Specifics: • Main Group Elements: Groups 1-2, 13-18 • Alkali Metals: Group 1 (extremely reactive metals) • Alkaline Earth Metals: Group 2 • Halogens: Group 17 (very reactive non-metals) • Noble Gases: Group 18 (non-reactive gases) • Transition Metals: Groups 3-12 • Lanthanides: Top row of the bottom section • Actinides: Bottom row of the bottom section

22. Periodic Tables - Activity • On the blank periodic table, colour code each section, label them • Metals • Non-metals • Metalloids • Alkali Metals • Alkaline Metals • Transition Metals • Lanthanides/Actinides • Halogens • Noble Gases

23. Periodic Tables • Tell you a lot of information • Elements in the same groups have similar bonding properties and reactivity patterns • Elements in the same periods have similar sizes • As you increase in number on the periodic table, you increase in atomic mass • They often contain the following information: • Atomic Number • Atomic Mass • Electronegativity • Element Charges

24. Determining #Protons, Electrons, Neutrons • Atomic Number (P): Number of Protons • # p = # e- • Atomic Mass (M): Number of Protons (P) + Number of Neutrons (N) • M = P + N

25. Example • Determine the number of protons, neutrons and electrons in neutral a. Iron-56 b. Bismuth-209

26. Atomic Symbols Z Mass Number: M P Atomic Number:

27. Homework: • Page 15 #2,3,4,6 • Worksheet: Protons, Neutron, and Electrons

28. I CAN: • Understand the difference between observation and inference • Understand the difference between theoretical and empirical knowledge • Explain the development of the atomic model • Describe the relationship between atomic number, atomic mass, and the different subatomic particles • Relate observations and inferences and describe real world examples

29. Next Class: • Quiz: Observation/Inference, Theoretical/Empirical, Periodic Table, Atomic Models, Electrons/Protons/Neutrons • Required: Name of Element for Element Assignment • Topics: Electromagnetic Spectrum, Bohr’s Model, Chemical Bonding