1. Atomic Structure and The Periodic Table Mr. Chan Northwestern University To insert your company logo on this slide From the Insert Menu Select “Picture” Locate your logo file Click OK To resize the logo Click anywhere inside the logo. The boxes that appear outside the logo are known as “resize handles.” Use these to resize the object. If you hold down the shift key before using the resize handles, you will maintain the proportions of the object you wish to resize.

2. Today (Day 18) (0-10) Return/Discuss Tests (0-10) Return/Discuss Tests (10-15) Activate: Sketch Atom (10-15) Activate: Sketch Atom (15-20) Mystery Box (15-20) Mystery Box (20-30) Dalton’s Atomic Theory (20-30) Dalton’s Atomic Theory (30-43) Word Splash (30-43) Word Splash Video – WOC The Atom (30 min) Video – WOC The Atom (30 min) Conferences Conferences

3. Mystery Boxes Procedure: Procedure: Select a Mystery Box. Without opening it, try to learn about its contents by using all the tools of observation available to you. Outline your plan to determine the contents of the box and record all observations you make. Select a Mystery Box. Without opening it, try to learn about its contents by using all the tools of observation available to you. Outline your plan to determine the contents of the box and record all observations you make.

4. Mystery Boxes Questions: Questions: 1. What evidence supports your conclusion about the type of item contained in the box? 1. What evidence supports your conclusion about the type of item contained in the box? 2. What kinds of things can you do to determine the contents of your box if you had access to other kinds of observational tools? 2. What kinds of things can you do to determine the contents of your box if you had access to other kinds of observational tools? 3. Since you cannot see what is inside, how can you be 100% sure of its contents? 3. Since you cannot see what is inside, how can you be 100% sure of its contents?

5. What are atoms? Smallest particle of element that retains properties of the element Smallest particle of element that retains properties of the element Possible to see individual atoms Possible to see individual atoms Demo: Al Foil – Physical Changes – Smallest Piece Demo: Al Foil – Physical Changes – Smallest Piece

6. History of Atomic Theory Original model – Democritus Original model – Democritus Atomos – smallest unit of matter Atomos – smallest unit of matter Dalton’s Theory Dalton’s Theory 1) Elements composed of tiny indivisible (not invisible) particles called atoms 1) Elements composed of tiny indivisible (not invisible) particles called atoms 2) Atoms of the same element are identical 2) Atoms of the same element are identical 3) Atoms of different elements can chemically combine with one another in simple whole number ratios (compounds) 3) Atoms of different elements can chemically combine with one another in simple whole number ratios (compounds) 4) In chemical reactions, atoms are separated, joined, and rearranged. Atoms of one element are never changed. 4) In chemical reactions, atoms are separated, joined, and rearranged. Atoms of one element are never changed.

7. Today (Day 19) (0-5) Discuss HW (0-5) Discuss HW (5-10) Demo (5-10) Demo (10-25) Experiments – discovery of Atomic Structure (10-25) Experiments – discovery of Atomic Structure (25-35) Rutherford’s Au Experiment (25-35) Rutherford’s Au Experiment (35-43, 0-25) LAB (35-43, 0-25) LAB (25-43) Numbers associated with At.Structure (25-43) Numbers associated with At.Structure

8. What is the structure of an atom? Electrons Electrons J.J. Thomson, cathode ray tubes – Overhead J.J. Thomson, cathode ray tubes – Overhead Electric current flowing through gases Electric current flowing through gases Beam – cathode ray travels from cathode (-) to the anode (+) Beam – cathode ray travels from cathode (-) to the anode (+) Metal plates – beam attracted to positive plate Metal plates – beam attracted to positive plate Electrons: negative, 1/2000 mass of hydrogen atom Electrons: negative, 1/2000 mass of hydrogen atom Millikan – oil drop experiments Millikan – oil drop experiments determined charge/mass ratio of electron determined charge/mass ratio of electron Mass of electron = 1/1840 mass of hydrogen atom Mass of electron = 1/1840 mass of hydrogen atom

9. Structure cont. Protons – positively charged particles Protons – positively charged particles Needed to balance charge of electrons in atom Needed to balance charge of electrons in atom Goldstein – CRT with loss of electrons – canal rays from cathode traveling in opposite direction as electrons Goldstein – CRT with loss of electrons – canal rays from cathode traveling in opposite direction as electrons Neutrons – no charge, mass - proton Neutrons – no charge, mass - proton Chadwick – knew some mass was unaccounted for Chadwick – knew some mass was unaccounted for

10. Summary of Subatomic particles Particle, symbol, relative charge, relative mass, actual mass Particle, symbol, relative charge, relative mass, actual mass

11. Rutherford’s Gold Foil Experiment

12. Led to discovery that most of the atom is empty space Led to discovery that most of the atom is empty space All of the positive charge and most of the atom’s mass found in a small region All of the positive charge and most of the atom’s mass found in a small region Nucleus of the atom Nucleus of the atom Core that contains protons and neutrons Core that contains protons and neutrons

13. Models of Atoms

14. Numbers Associated with Atomic Structure Atomic Number Atomic Number Number of protons in nucleus of atom of element Number of protons in nucleus of atom of element Also equals number of electrons if electrically neutral Also equals number of electrons if electrically neutral Determines which element you have Determines which element you have Practice: How many protons and electrons, what the symbol, element name is Practice: How many protons and electrons, what the symbol, element name is Mass number Mass number Total number of protons and neutrons Total number of protons and neutrons Not given on the periodic table Not given on the periodic table

15. Calculating Number of Protons, Neutrons, and Electrons Number of neutrons = Mass Number – Atomic Number Number of neutrons = Mass Number – Atomic Number Shorthand Notation: Mass/Atomic – Element Shorthand Notation: Mass/Atomic – Element OR Element – Mass number OR Element – Mass number Practice #9-12: Determine number of protons, electrons, and neutrons, completing tables of atomic number, mass number, #protons, #neutrons, #electrons, symbol – notation, Determining from symbol: #neutrons Practice #9-12: Determine number of protons, electrons, and neutrons, completing tables of atomic number, mass number, #protons, #neutrons, #electrons, symbol – notation, Determining from symbol: #neutrons

16. Today (Day 20) (0-5) Opener (0-5) Opener (5-15) Discuss HW (5-15) Discuss HW (15-30) Quiz (15-30) Quiz (30-43) Isotopes (30-43) Isotopes

17. What are Isotopes? Atoms that have the same number of protons but different numbers of neutrons Atoms that have the same number of protons but different numbers of neutrons Different mass numbers Different mass numbers Atoms are chemically alike – behave similarly Atoms are chemically alike – behave similarly Common misconception: radically different – NO! Common misconception: radically different – NO! Examples: 3 isotopes of hydrogen Examples: 3 isotopes of hydrogen Tritium – Spiderman 2 errors – MOVIE CLIP Tritium – Spiderman 2 errors – MOVIE CLIP Gas, not solid Gas, not solid More than 25 pounds in world More than 25 pounds in world Chemical symbols, Subatomic particles examples for isotopes (O-16,17,18) Chemical symbols, Subatomic particles examples for isotopes (O-16,17,18) Symbolic Notation - isotopes Symbolic Notation - isotopes

18. Today (Day 21) (0-10) Opener/Discuss HW (0-10) Opener/Discuss HW (10-15) Discuss QUIZ (10-15) Discuss QUIZ (15-20) Spiderman 2 Clip (15-20) Spiderman 2 Clip (20-30) Activity: Isotope Numbers Relay Race (20-30) Activity: Isotope Numbers Relay Race (30-43) Average Atomic Mass (30-43) Average Atomic Mass (0-43) Isotopes and Atomic Mass Lab (0-43) Isotopes and Atomic Mass Lab

19. Opener - 9/29 Determine the number of protons, neutrons, and electrons in the following isotopes: Determine the number of protons, neutrons, and electrons in the following isotopes: Hydrogen-1, Hydrogen-2, and Hydrogen-3 Hydrogen-1, Hydrogen-2, and Hydrogen-3

20. What is average atomic mass? Weighted grades analogy Weighted grades analogy Masses of subatomic particles ridiculously small – needed something more convenient Masses of subatomic particles ridiculously small – needed something more convenient Arbitrary amount set: Carbon-12 atom = 12.00000 amu Arbitrary amount set: Carbon-12 atom = 12.00000 amu 1 amu (atomic mass unit) = 1/12 mass of C-12 atom 1 amu (atomic mass unit) = 1/12 mass of C-12 atom Mass of a single proton/neutron – 1 amu Mass of a single proton/neutron – 1 amu Why are the masses decimals? Why are the masses decimals? Most elements exist as a mixture of 2 or more isotopes Most elements exist as a mixture of 2 or more isotopes Look at average atomic masses of elements – can you speculate which isotope is most common? Look at average atomic masses of elements – can you speculate which isotope is most common?

21. How do you calculate average atomic mass? Average atomic mass = weighted average mass of atoms in naturally occurring sample Average atomic mass = weighted average mass of atoms in naturally occurring sample Number on Periodic Table – explains why we could not use as mass number Number on Periodic Table – explains why we could not use as mass number Reflects both the mass and the relative abundance of the isotopes as they occur in nature Reflects both the mass and the relative abundance of the isotopes as they occur in nature Calculating average atomic mass Calculating average atomic mass First, example of which is closer? First, example of which is closer? Next, an example comparing to weighted average in class (grades) Next, an example comparing to weighted average in class (grades) Finally, example using exact percentages and masses Finally, example using exact percentages and masses Finish HW/EC problems Finish HW/EC problems Practice#14,16 Practice#14,16

22. Today (Day 22) Read Article Read Article Socratic Seminar Socratic Seminar

23. Today (Day 24) Review Review

24. Today (Day 25) Chapter 4 Test Chapter 4 Test

25. Origin of Periodic Table Mendeleev Mendeleev Listed elements in columns and in order of increasing atomic mass Listed elements in columns and in order of increasing atomic mass Elements in groups with similar properties Elements in groups with similar properties Moseley Moseley Determined atomic numbers Determined atomic numbers Rearranged periodic table to current state Rearranged periodic table to current state P-Tables Online P-Tables Online HTML Table HTML Table HTML Table HTML Table Interactive Periodic Table Interactive Periodic Table Interactive Periodic Table Interactive Periodic Table Comic Book P-Table Comic Book P-Table Comic Book P-Table Comic Book P-Table

26. Organization of Periodic Table Increasing atomic number Increasing atomic number Periods Periods Horizontal rows Horizontal rows Groups Groups Vertical columns of elements Vertical columns of elements Periodic law Periodic law Repetition of chemical and physical properties Repetition of chemical and physical properties Representative elements Representative elements Metals (alkali, alkaline earth, transition) Metals (alkali, alkaline earth, transition) Nonmetals (halogens, noble gases) Nonmetals (halogens, noble gases) Metalloids Metalloids