1. Chapter 2: Modern Atomic Theory Matter consists of atoms Atoms consist of three fundamental particles, found in the nucleus and the space around the nucleus

2. Arrangement of Subatomic Particles not to scale! If an atom has a diameter of about 100 m (a football field), the nucleus would be 1 mm in diameter Nucleus contains protons and neutrons.

3. What holds an atom together?

4. Coulomb’s Law of electrostatic interactions.

5. What holds an atom together? Coulomb’s Law of electrostatic interactions. General Behavior: Like charges repel. Opposite charges attract.

6. What holds an atom together? Coulomb’s Law of electrostatic interactions. If we double a charge from +1 to +2, the force will: 1.Double 2.Halve 3.Quadruple 4.Quarter

7. What holds an atom together? Coulomb’s Law of electrostatic interactions. If we double the distance, the force will: 1.Double 2.Halve 3.Quadruple 4.Quarter

8. What’s wrong with this picture? Electrons are held near the nucleus by the electrostatic attraction between them, but …

9. How could we possibly know that the nucleus is small compared to the size of the atom? Why not think the protons, electrons and neutrons are all mixed together? The Rutherford Experiment We’re not just making it up!

10. The Rutherford Experiment We’re not just making it up!

11. The Rutherford Experiment We’re not just making it up! It’s the difference between walking through fog and hail.

12. Isotopes Isotopes are atoms of an element with the same number of protons but different numbers of neutrons, and different mass Atom symbols are written using the following format: X = symbol of element A = mass number Z = atomic number

13. Isotopes, continued Most elements have multiple isotopes – 1 H, 2 H (deuterium), 3 H (tritium, radioactive) – 79 Br, 81 Br – 64 Zn, 66 Zn, 67 Zn, 68 Zn, 70 Zn While atomic mass is the mass of an atom, average atomic mass takes into account isotopes and natural abundance We use atomic mass units (amu) 1 amu = 1.661 x 10 –24 g (about the mass of a proton)

14. What is the average weight of students on a sports team?

15. Isotopes and Average Atomic Masses An element has: 60.4% 68.9 amu 39.6% 70.9 amu What is atomic weight?

16. ? 1.. 2.. 3.. 4..

17. Who cares? Question:

18. Isotope labeling studies

19. Uranium Isotopes, reactors and bombs

20. The electrostatic force and Hurricanes!

21. The Periodic Table The real structure…

22. The Periodic Table

23. Groups and Periods

24. The Periodic Table Main and Transition Groups

25. The Periodic Table Metals, Nonmetals, Metalloids

26. The Periodic Table Groups with names.

27. Structures of the Elements

29. What percentage of elements are metals? 1.10% 2.25% 3.50% 4.75% 5.90%

30. Metallic character increases… 1.Moving left 2.Moving down 3.left and down 4.Right 5.Up 6.Right and up