1. Unit 3 – Atomic Structure

2. Chapter 3 section 1 Two early thoughts on atomic structure Aristotle Democritus

3. Chapter 3 section 1 Dalton’s Atomic Theory was the first based on experimental evidence 1) 2) 3) 4) 5)

4. Chapter 3 section 1 Picture of Dalton’s atomic model Parts of Dalton’s theory were proven false:

5. Chapter 3 section 2 JJ Thomson discovered electrons using a cathode ray tube

6. Chapter 3 section 2 Picture of Thomson’s atomic model

7. Chapter 3 section 2 Rutherford discovered the nucleus using the gold foil experiment gold foil experiment

8. Chapter 3 section 2 Rutherford’s prediction

9. Chapter 3 section 2 Actual result of Rutherford’s experiment

10. Chapter 3 section 2 Interpretation of Rutherford’s experiment

11. Chapter 3 section 2 Picture of Rutherford’s atomic model

12. Chapter 3 section 3 Subatomic particles ParticleSymbolCharge Relative mass protonp+p+ +11 electrone-e- 0 neutronn0n0 01

13. Chapter 3 section 3 Atoms have no net charge, so the number of _______ is equal to the number of ________. Atoms of the same element have the same number of ________. Atomic number is the number of protons in the atom.

14. Chapter 3 section 3 1) What is the atomic number of carbon? 2) What is the atomic number of xenon? 3) How many protons are in an atom of nickel? 4) What element is atomic number 55? 5) What element has 50 electrons?

15. Chapter 3 section 3 Atoms of the same element can have different number of __________. Atomic of the same element that have different number of neutrons are called isotopes. The number of protons + number of neutrons is called the mass number. (Do you see mass number on the periodic table?)

16. Chapter 3 section 3 Ways to represent isotopes:

17. Chapter 3 section 3 Element# p + # e - #n 0 H-1 3240 37 Cl Sr40 13 130 ”X”77

18. Chapter 3 section 3 What about atomic mass?

19. Chapter 3 section 3 The atomic mass is defined as the weighted average of the isotopic masses of an element. Average the masses of the isotope of carbon to give the atomic mass

20. Chapter 3 section 3 How to calculate atomic mass.

21. Chapter 3 section 3 1. What is average atomic mass of Lithium if 7.42% exists as 6 Li (6.015 g/mol) and 92.58% exists as 7 Li (7.016 g/mol)? 2. Magnesium has three naturally occuring isotopes. 78.70% of Magnesium atoms exist as Magnesium-24, 10.03% exist as Magnesium-25 and 11.17% exist as Magnesium-26. What is the average atomic mass of Magnesium? 3. Neon has two major isotopes, Neon-20 and Neon-22. Out of every 250 neon atoms, 225 will be Neon-20, and 25 will be Neon- 22. What is the average atomic mass of Neon?

22. Chapter 3 section 3 4. What is the atomic mass of Hafnium if out of every 200 atoms, 10 have mass 176.00 g/mol, 38 have mass 177.00 g/mol, 54 have mass 178.00 g/mol, 28 have mass 179.00 g/mol, and 70 have mass 180.00 g/mol? 5. In a sample of 200 Chlorine atoms, it is found that 151 are 35 Cl and 49 are 37 Cl. What is the average atomic mass of Chlorine? 6. Without doing any math, are there more Bromine-79 atoms or more Bromine-80 atoms on earth? (Hint: look at the periodic table.)

23. How did we get today’s atomic model?

24. Chapter 4 section 1

25. Bohr shown light through hydrogen gas. Bohr’s prediction was a continuous spectrum

26. Chapter 4 section 1 Actual result of Bohr’s experiment

27. Chapter 4 section 1 Picture of Bohr’s atomic model

28. Chapter 4 section 1 Explanation of hydrogen emission spectra

29. Chapter 4 section 2 Bohr’s model only correctly predicted the behavior of hydrogen Today’s modern atomic theory is the Quantum Mechanical Model

30. Chapter 4 section 2 Quantum Mechanical Model uses four numbers to describe the probable location the electron 1) 2) 3) 4)

31. Chapter 4 section 3 Orbital filling diagram

32. Chapter 4 section 3 Rules governing electron filling order Aufbau principle- Hund’s rule – Pauli exclusion priciple -

33. Chapter 4 section 3 Electron configuration

34. Periodic table and e- configuration