1. Chapter 4 Atomic structure

2. Aristotle

3. Democritus About 400BC Matter made of individual pieces “ATOMOS”

4. Dalton 1766-1844 Explored 2000 yrs of chemistry knowledge Atomic Theory – Atoms – Different elements…different atoms – Atoms REARRANGED in reactions – Compounds always built the same way from the same atoms: – Water is 2 H and 1 O

5. Thomson Discovered ELECTRON – Cathode Ray – Negative particle Atoms are neutral…. – Must be positive material in there too. ALL metals have SAME ELECTRONS!

6. Rutherford Tried to prove Thomson’s Model GOLD FOIL EXPERIMENT “Discovered” the NUCLEUS – Tiny – Positive

7. 4.2 Atomic Structure

8. Our View of the Atom

12. Henry Moseley 1887-1915 (died WW1) Student of Rutherford Elements are different because of different # of PROTONS ATOM IDENTITY IS TIED TO # OF PROTONS ALL CARBON HAVE SAME # of PROTONS! ALL NOT-CARBON HAVE DIFFERENT # of PROTONS FROM CARBON! ALL CARBON HAVE SAME # of PROTONS! ALL NOT-CARBON HAVE DIFFERENT # of PROTONS FROM CARBON!

13. Think! Nitrogen has 7 protons An atom has 6 protons… An atom has 7 protons… An atom has 5 neutrons… A neutral atom has 7 electrons… A neutral atom has 7 neutrons… An ion has 7 protons… OK It’s not N It’s N It’s ID isn’t known It’s N It’s ID isn’t known It’s N

14. ATOMIC NUMBER Tells the # of protons Usually above the symbol on the Periodic Table For a Neutral Atom Protons = Electrons 7 N 14.007

15. Try It OxygenCesium (Cs)Fluorine (F)Lead (Pb)Silver (Ag) 8 p+55 p+9 p+82 p+47 p+ 8 e-55 e-9 e-82 e-47 e-

16. Try It OxygenCesium (Cs)Fluorine (F)Lead (Pb)Silver (Ag) 8 p+55 p+9 p+82 p+47 p+ 8 e-55 e-9 e-82 e-47 e-

17. Try It OxygenCesium (Cs)Fluorine (F)Lead (Pb)Silver (Ag) 8 p+55 p+9 p+82 p+47 p+ 8 e-55 e-9 e-82 e-47 e-

18. Try It OxygenCesium (Cs)Fluorine (F)Lead (Pb)Silver (Ag) 8 p+55 p+9 p+82 p+47 p+ 8 e-55 e-9 e-82 e-47 e-

19. Try It OxygenCesium (Cs)Fluorine (F)Lead (Pb)Silver (Ag) 8 p+55 p+9 p+82 p+47 p+ 8 e-55 e-9 e-82 e-47 e-

20. Try It OxygenCesium (Cs)Fluorine (F)Lead (Pb)Silver (Ag) 8 p+55 p+9 p+82 p+47 p+ 8 e-55 e-9 e-82 e-47 e- GOOD JOB EVERYONE

21. Mass Number Not found on the Periodic Table (usually) TOTAL Number of particles in the Nucleus Protons + Neutrons Written 2 ways: 12 C 6 Carbon - 12

22. Try it 11 B 206 Pb Iodine-131 Boron-11 5 protons 6 neutrons Lead-206 82 protons 124 neutrons 53 protons 78 neutrons 131 I

23. Isotopes Same element Different Mass # Different number of neutrons NameProtonsneutrons Carbon-1266 Carbon-1468

24. Isotopes Same element Different Mass # Different number of neutrons NameProtonsneutrons Carbon-1266 Carbon-1468

25. Isotopes Same element Different Mass # Different number of neutrons NameProtonsneutrons Carbon-1266 Carbon-1468

26. Isotopes How many Isotopes? 4 What are their names? Strontium-84 Strontium-86 Strontium-87 Strontium-88 Which is most common? Strontium-88

27. Mercury

28. Ions CATION Positive Lost electron(s) 20 protons 22 neutrons 18 electrons ANION Negative Gained electron(s) 16 protons 17 neutrons 19 electrons

29. 4.3 The Modern Atom ENERGY ABSORBED? – KE of atom (temp change) – PE of atom (phase change) – Can be absorbed in one form and emitted as… LIGHT!LIGHT!

30. 4.3 The Modern Atom Niels Bohr 1885-1962 Model linked e- energy to light energy. “Planetary” Model nucleus electron ENERGY LEVELS orbits the nucleus

31. High Energy is far from nucleus Low Energy is close to nucleus Bohr’s Genius Idea: Electrons may only be on the levels (like stairs) But may change levels

32. Jumpy electrons? Absorb Release

33. Click my brain to see what I’m thinking.

34. Sorry, Let me collect my thoughts and we’ll try again.

35. Energy Levels Numbered: n = 1 is CLOSEST LOWEST ENERGY MOST ATTRACTED n = 4 is FARTHER HIGHER ENERGY LESS ATTRACTED n = 17?

36. Energy Levels Energy Level# electrons n = 12 n = 28 n = 318 n = 432 Each Level has a maximum e- capacity.

37. Energy Levels Energy Level# electrons n = 12 n = 28 n = 318 n = 432 Each Level has a maximum e- capacity.

38. Energy Levels Energy Level# electrons n = 12 n = 28 n = 318 n = 432 Each Level has a maximum e- capacity.

39. Energy Levels Energy Level# electrons n = 12 n = 28 n = 318 n = 432 Each Level has a maximum e- capacity.

40. Energy Levels Energy Level# electrons n = 12 n = 28 n = 318 n = 432 Each Level has a maximum e- capacity.

41. Ground State Occurs when atom’s electrons have LOWEST POSSIBLE ENERGY HELIUM 2 electrons

42. Lithium 3 electrons

43. Carbon 6 electrons

44. Sodium 11 electrons Any Similarities to Lithium?

45. TRUE/FALSE Electrons in energy levels Electrons change energy Electrons orbit nucleus (planet) TRUE (thanks Bohr) FALSE (sorry Bohr) Bohr’s ENERGY IDEA = CORRECT Bohr’s PICTURE = NOT CORRECT

46. CLOUD MODEL