1. Drill Calculate the the following: Mass = 39.2g; Vol = 27.2 mL; Density = ? Mass = 39 g; Density = 1g/mL; Volume =?

2. Objective SWBAT: Diagram the historical development of the atom in order to compare and contrast each model’s advantages/ limitations.

3. SAT/HSA Enrichment How many kilograms are equivalent to 345 grams?

4. WEB Organizer: To assess students’ prior knowledge about the current theory describing the model of the atom.

5. Defining the Atom What is the Atom?

6. Defining the Atom The lab technician shown here is using a magnifying lens to examine a bacterial culture in a petri dish. When scientists cannot see the details of what they study, they try to obtain experimental data that help fill in the picture.

7. Early Models of the Atom An atom is the smallest particle of an element that retains its identity in a chemical reaction. Philosophers and scientists have proposed many ideas on the structure of atoms.

8. Early Models of the Atom Democritus’s Atomic Philosophy Democritus believed that atoms were indivisible and indestructible. Democritus’s ideas were limited because they didn’t explain chemical behavior and they lacked experimental support.

9. Early Models of the Atom Dalton’s Atomic Theory By using experimental methods, Dalton transformed Democritus’s ideas on atoms into a scientific theory. The result was Dalton’s atomic theory.

10. Early Models of the Atom All elements are composed of tiny indivisible particles called atoms.

11. Early Models of the Atom Atoms of the same element are identical. The atoms of any one element are different from those of any other element.

12. Early Models of the Atom Atoms of different elements can physically mix together or can chemically combine in simple whole- number ratios to form compounds.

13. Early Models of the Atom Chemical reactions occur when atoms are separated, joined, or rearranged. Atoms of one element are never changed into atoms of another element in a chemical reaction.

14. Sizing up the Atom Despite their small size, individual atoms are observable with instruments such as scanning tunneling microscopes. Iron Atoms Seen Through a Scanning Tunneling Microscope

15. Short Quiz 1. The ancient Greek philosopher credited with suggesting all matter is made of indivisible atoms is a. Plato. b. Aristotle. c. Democritus. d. Socrates.

16. Short Quiz 2. Dalton's atomic theory improved earlier atomic theory by a. teaching that all matter is composed of tiny particles called atoms. b. theorizing that all atoms of the same element are identical. c. using experimental methods to establish a scientific theory. d. not relating atoms to chemical change.

17. Short Quiz 3. Individual atoms are observable with a. the naked eye. b. a magnifying glass. c. a light microscope. d. a scanning tunneling microscope.

18. The Atomic Structure Groups: Each group will have one person for each atomic theory.

19. Groups: (20 min)(20 min) Groups: Responsible for completing the information for their atomic theory on the Atomic theory worksheet. Responsible for drawing a model of their atom from their atomic theory.

20. Groups: Responsible for sharing information that was gathered about all the atomic theories to the class, as well as draw an illustration of the atom to go with their findings.

21. Illustrations: (10 min)(10 min) Students will observe all of the illustrations that were created in each group. Discuss the distinguishing features and advantages/limitation of each atomic model.

22. Analysis/Summary Questions Complete the Summary questions. (10 min) (10 min)

23. Summary 1. How did Democritus characterize atoms? 2. How did Dalton advance the atomic philosophy proposed by Democritus? 3. What instrument can be used to observe individual atoms? 4. In your own words, state the main ideas of Dalton’s atomic theory. 5. According to Dalton’s atomic theory, is it impossible to convert atoms of one element into atoms of another? Explain.

24. Exit ticket: Complete Atomic Structure worksheet. Homework: Complete Atomic Theory Homework