1. Catalyst – September 2(7), 2010 1. What is the atomic number of silicon (Si)? 2. How many protons, neutrons, and electrons does sodium (Na) have? 3. Who discovered the electron? HW OUT PLEASE!

2. Today’s Agenda  Catalyst  Homework Review  Bohr Models!  Personal and Group Work Time  Exit Question  Return and go over Quizzes (10 min)  Progress Reports

3. Today’s Objectives  SWBAT draw Bohr models of the first 20 elements on the periodic table.  SWBAT draw Bohr models for 5 elements in their family.

4. Front DoorProjector 3rd Period Group 3 Ebony, Waynell, Quanetta, Warren Group 5 Alessandro, Bao, Kara Group 1 Chicobi, Tashelle, Jamie, Sara Group 6 Kendell, Jasmine, Corey, Kiedra Group 2 Melvin, Paula, Amber, Tigler Group 4 Brandon, Ariel, Shawn

5. Front DoorProjector 4th Period Group 3 Infinity, Jytte, Lyndon, Jeremy Group 2 Khallid, Shannon, Rodrea, Daniel Group 1 Jon, Sam, Josh’shawn, Kourtney Group 6 Kentrell, Eddie, Artrel, Darreal Group 5 Lester, Dwanyetta, Jaron, Aaron Group 4 Brittany, Chelsie, Troy, Nia Group 9 Group 8 Kim, Roniece, Caleb Group 7 Lizzeh, Rachel

9. Atomic Number (small whole number) Navigating the Periodic Table Element Symbol (letters) Atomic Mass (big decimal number)

10. Atomic Number is an Element’s ID Number  Like your social security number or a professional athlete’s jersey number, the atomic number of an element identifies that element

11. Navigating the Periodic Table  What is the atomic number of… 1. Lithium? 2. Magnesium? 3. Silver? 4. Boron? 3 12 47 5

12. Find the atomic number of this element

14. Bohr Models of Atoms  Key Point #1: A Bohr model depicts an atom as a small, positively charged nucleus surrounded by electrons that travel in circular orbits around the nucleus 16 p+ 16 n o Sulfur: 16 protons 16 neutrons 16 electrons

15. Energy Levels  Key Point #2: Energy levels (or shells) are paths around the nucleus where electrons travel  Energy levels are also known as orbits  Energy increases as you move further from the nucleus

16. Valence Electrons  Key Point #3: Valence electrons (ve-) are electrons in the outermost energy level  They are the furthest from the nucleus  An atom could have 1 ve-, 2 ve-, 3 ve-, etc.

17. Steps to Making a Bohr Model 1. Determine the number protons, neutrons, and electrons in the atom 2. Draw the nucleus (circle) with # p+ and # n o inside 3. Draw the first energy level (circle around nucleus) and draw up to 2 dots (electrons) 4. If needed, draw second energy level (second circle) and draw up to 8 dots (electrons) 5. If needed, draw third energy level (third circle) and draw up to 8 dots (electrons) 6. If needed, draw fourth energy level (fourth circle) and draw up to 18 dots (electrons)

18. Work Time  Draw Bohr Models for the first 20 elements on your notes sheet  We will do a few together first  Remember, find the number of protons, electrons, and neutrons first…then get drawing!  Work for at least 10 minutes on your own…then finish sheet on your own time  Work with your group members to draw Bohr models for 5 of your family’s elements

19. Exit Question 1. Draw the Bohr model for Lithium (Li). Homework: Quiz 2.1 Resume, Trends w/ Bohr Models Worksheet, Work on Project

20. Quiz Averages  3 rd Period: 71.8%   4 th Period: 69.9% 

21. Theory Reading New advances in radiocarbon dating are threatening to alter old theories about when modern humans migrated to Europe from Africa and how rapidly they advanced. The research casts new light on significant patterns of human migration into Central and Western Europe in the crucial period from 50,000 to 35,000 years ago, scientists say. It suggests that the dispersal of anatomically modern Homo sapiens into Europe was more rapid than previously thought. For years, it had been thought that modern humans from Africa began arriving in Western Europe at least 40,000 years ago, and so could have competed and mingled with the local population for at least 12,000 years. The revised dating of fossils and artifacts leaves much less time for two species to have been in close contact. Radiocarbon dating, introduced shortly after World War II, has been widely used in measuring time in prehistory. It works by measuring the rate of decay of carbon 14 in once living materials, like plant and animal remains. Recent research at the University of Oxford has led to a more effective filtration process to reduce contamination in test samples; however, contamination can still happen. In previous estimates, the modern human dispersal through Europe occurred 43,000 to 36,000 years ago. The 7,000-year period implies an overall dispersal rate of about 0.3 kilometers a year, less than two-tenths of a mile. Starting somewhat earlier, the faster dispersal over 5,000 years is now clocked at 0.4 kilometers a year. Scientists cautioned that the revised dating based on new research must be viewed as provisional, concluding that the implications of the new studies "will need to be kept under active and vigilant review."