2. 1 Negative particles Positive particles Neutral particles

3. 2 Why do most of the alpha particles pass through?

4. 3 1 angstrom = 1 x 10 -10 m

5. 4 nucleus Proton charge = +, mass = 1.0073 amu atomic mass units: 1amu = 1.6605402 x 10 -24 g Neutron charge = neutral, mass = 1.0087 Electron charge = 1-, mass = 5.4586 x 10 -4 amu Almost all the mass is in the nucleus, and almost all the volume is due to the electrons!

6. 5 Almost all the mass is in the nucleus, and almost all the volume is due to the electrons! One penny If this penny consisted of just nuclear material it would weigh……... 190,000,000 TONS!!!

7. 6 In a neutral atom, the number of (+) protons = the number of (-) electrons And.. The number of protons is equal to the atomic number of the element. Since the mass of an atom is almost entirely located in the nucleus, the mass number is equal to: the number of protons PLUS the number of neutrons

8. 7 The lower numbers found on most periodic tables are the ATOMIC MASSES (WEIGHTS) NOT the ATOMIC MASS NUMBER!

9. 8 Isotopes: same element, different atomic mass. How can this be?

10. 9 Isotopes: same element, different atomic mass. How can this be? If it’s the same element, the number of protons can’t change. So what must change? Isotopes: same element, different number of neutrons.

11. 10 11 C 12 C 13 C 14 C ISOTOPES No. protons: No. Electrons: No. neutrons: 6 666 666 6 5 6 7 8

12. 11 99.63% 14.0031 amu 0.37% 15.0001 amu ISOTOPES OF NITROGEN

13. 12 C-12 basis for the atomic mass scale

14. 13 Atomic mass or weight: the weighted average of the atomic masses of all naturally occurring isotopes present. Atomic # Atomic mass or weight 75.53% 24.47% Naturally occurring ISOTOPES: 34.9689 amu 36.9659 amu x 0.7553 = 26.412 x 0.2447 = 9.045 35.45 Atomic mass on periodic table

15. 14 “Losers” Metals lose e - ’s in chemical reactions Boy there are a lot of losers!

16. 15 non-metals:gain electrons (or share) metalloids:

17. 16 Why is O a non metal and Po a metal? Nucleus

18. 17 1 2 3 4 5 6 7 periods periods

19. 18 1 2 3 4 5 6 7 Groups or families

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21. 20 Molecular Compounds: (molecules) CO 2 CO H2O2H2O2 O3O3 H2OH2O O2O2 CH 4 C2H4C2H4

22. 21 7 diatomic elements 6 + 1 = 7

23. 22 Molecular structures:

24. 23 Molecular and Empirical Formulas: Simplest Form Actual formula butene: C 4 H 8 molecular or empirical? What is the empirical formula? CH 2 Carbon dioxide: CO 2 empirical or molecular?

25. 24 Ions and ionic compounds: cation: positive charge (lost e - ’s) Na + 11 protons and only 10 electrons anion: negative charge (extra e - ’s) Cl - 17 protons and 18 electrons

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