1. Alchemy Unit Investigation III: A Particulate World Lesson 1: Pudding and Clouds Lesson 2: Building Atoms Lesson 3: Subatomic Heavyweights Lesson 4: Life on the Edge Lesson 5: Shell Game Lesson 6: Go Figure Lesson 7: Technicolor Atoms

2. Alchemy Unit – Investigation III Lesson 1: Pudding and Clouds

3. ChemCatalyst • In the 5th century BCE a Greek philosopher named Leucippus and his student, Democritis, stated, “All matter is made up of particles that can be divided called atoms.” • What do you think atoms are? Unit 1 • Investigation III

4. The Big Question • How have chemists thought about the atom through history? Unit 1 • Investigation III

5. You will be able to: • Describe some models of an atom and explain how they differ. Unit 1 • Investigation III

6. Notes • Atoms are extremely small particles, which cannot be seen, even with microscopes. • All matter is made up of atoms. • Scientists have created models to describe atoms. Models are similar to theories, but often include a picture or physical representation. (cont.) Unit 1 • Investigation III

7. (cont.) • When a model is supported by scientific evidence it is often accepted by the scientific community. • Scientific evidence is a collection of observations that many people have made. Everyone agrees on the same collection of observations. • As new evidence is gathered, models are refined and changed. Unit 1 • Investigation III

8. Activity • Purpose: This lesson will introduce you to various models for the atom that have appeared over the past two hundred years. The descriptions of five models of the atom are on a separate handout. (cont.) Unit 1 • Investigation III

9. (cont.) • Five Models of the Atom Unit 1 • Investigation III

10. Making Sense • Examine the date of the atomic evidence and then put the five models in the correct order of their introduction to the world of science. Unit 1 • Investigation III

11. Notes • An atom is mostly empty space. • The rest consists of a nucleus, which is located in the very center of the atom, and electrons, which are located around the nucleus. • The nucleus is very small (it would be nothing more than a tiny speck in our drawings, if we were to draw it to scale). (cont.) Unit 1 • Investigation III

12. Notes (cont.) • The nucleus is also very dense and consists of two types of particles—neutrons and protons. • A neutron is a neutral particle with no charge on it. • A proton is a positively charged particle. • Tightly bound together, neutrons and protons make a positively charged nucleus. (cont.) Unit 1 • Investigation III

13. Notes (cont.) Unit 1 • Investigation III

14. Check-In • Here is a Bohr model of a carbon atom. • List two things this model tells you about atoms. • List something this model does not tell you about atoms. Unit 1 • Investigation III

15. Wrap-Up • All matter is made up of extremely small particles called atoms. These particles are too small to be seen even with a microscope. • Science is theoretical and dynamic. Models and theories are continually being revised, refined, or replaced with new models and theories. Unit 1 • Investigation III

16. Alchemy Unit – Investigation III Lesson 2: Building Atoms

17. Helium, He Berylium, Be ChemCatalyst • A Bohr model of a helium atom and a beryllium atom are given below. (cont.) Unit 1 • Investigation III

18. (cont.) • List three similarities and three differences. • How do you think a gold atom is different from a copper atom? Unit 1 • Investigation III

19. The Big Question • What does the periodic table tells us about the structures of different atoms? Unit 1 • Investigation III

20. You will be able to: • Use the periodic table to identify the properties of an elements atom. Unit 1 • Investigation III

21. Notes • Atomic number is the number of protons in the nucleus of an atom. • Mass number is the mass of an individual atom. Unit 1 • Investigation III

22. Beryllium Atom Fluorine Atom Carbon Atom Activity • Purpose: This lesson will formally introduce you to atomic structure. (cont.) Unit 1 • Investigation III

23. (cont.) Unit 1 • Investigation III

24. Making Sense • If you know the atomic number of an element, what other information can you figure out about the atoms of that element? • If you know the atomic number of an element, can you figure out how many neutrons an atom of that element has? Can you come up with a close guess? Explain. Unit 1 • Investigation III

25. Notes • Mass number is the number of protons plus the number of neutrons. • Atomic mass is the “weight” or mass of a single atom. • Atomic weight is the decimal number on the periodic table. Unit 1 • Investigation III

26. Check-In • Use your periodic table to identify the following elements: • a) Atomic number 18 • b) Has three electrons • c) Atomic mass of 16.0 Unit 1 • Investigation III

27. Wrap-Up • Each successive element has one more proton than the element preceding it. • The atomic number is equal to the number of protons. (cont.) Unit 1 • Investigation III

28. (cont.) • The number of electrons is equal to the number of protons (as long as the atom is neutral). • The mass number is equal to the number of protons plus the number of neutrons (most of the mass is found in the nucleus). Unit 1 • Investigation III

29. Alchemy Unit – Investigation III Lesson 3: Subatomic Heavyweights

30. ChemCatalyst • A chemist investigating a sample of lithium found that some atoms have a lower mass than other atoms. The chemist determined that the structures of the two types of atoms would be similar to the two drawings below. (cont.) Unit 1 • Investigation III

31. (cont.) • What is different about the two atoms? • What is the atomic number of each atom? • What is the mass number of each atom? • Do you think they are both lithium atoms? Why or why not? Unit 1 • Investigation III

32. The Big Question • How do isotopes of an atom account for the atomic weight of an element? Unit 1 • Investigation III

33. You will be able to: • Predict the isotopes of an element. Unit 1 • Investigation III

34. Notes • Atoms of the same element that have different numbers of neutrons are called isotopes. • Atomic mass units (amu) are “invented” measurement units of the atomic mass. Unit 1 • Investigation III

35. Activity • Purpose: In this lesson you will investigate isotopes and how they affect atomic weight. (cont.) Unit 1 • Investigation III

36. (cont.) (cont.) Unit 1 • Investigation III

37. (cont.) Unit 1 • Investigation III

38. Making Sense • Explain why the atomic weights listed in the periodic table are not usually whole numbers. Unit 1 • Investigation III

39. Notes • While the element iron is defined as being made up of neutral atoms with 26 protons and 26 electrons, not every iron atom has the same number of neutrons. • Atoms that have the same number of protons but different numbers of neutrons are called isotopes. (cont.) Unit 1 • Investigation III

40. Notes(cont.) • What we call the atomic weight on the periodic table is actually the average atomic mass of that element’s naturally occurring isotopes. • Isotopes have similar chemical properties in that they combine with other elements to form similar compounds. (cont.) Unit 1 • Investigation III

41. (cont.) • Atomic Weight is the weighted average of the atomic masses of different isotopes taking into account their abundance. (cont.) Unit 1 • Investigation III

42. (cont.) Unit 1 • Investigation III

43. Check-In • Predict the isotopes of carbon, C. Which isotope is more abundant? How do you know? Unit 1 • Investigation III

44. Wrap-Up • Elements may have anywhere from 2 to 10 naturally occurring isotopes. • The atomic weight of an element listed on the periodic table is actually the average mass of the naturally occurring isotopes of that element. • Isotopes have the same number of protons and electrons, but different numbers of neutrons. (cont.) Unit 1 • Investigation III

45. (cont.) • Isotopes of a single element exhibit similar properties in that they form similar compounds. • Isotopes are referred to by their mass numbers. Unit 1 • Investigation III

46. Alchemy Unit – Investigation III Lesson 4: Life on the Edge

47. ChemCatalyst • The three atoms below have similar reactivity and chemical behavior. • Where are these elements located on the periodic table? • What do you think might be responsible for their similar properties? (cont.) Unit 1 • Investigation III

48. (cont.) Unit 1 • Investigation III

49. The Big Question • What accounts for the similar chemistry of elements in the same group? Unit 1 • Investigation III

50. You will be able to: • Give the number of valence electrons for an element. Unit 1 • Investigation III