Spark Will Not Be Stamped!

1. Spark Will Not Be Stamped! • What is an isotope? • What particles are involved with isotopes? • Why is the mass on the periodic table a decimal? Rubidium has two common isotopes Rb– 85 and Rb – 87. If the abundance of Rb – 85 is 72.2 % and the abundance of Rb – 87 is 27.8%, then what is the average atomic mass of rubidium?

2. Spark What is the relationship between electricity and matter? Why do you think some substances conduct electricity and some do not? How does the conductivity tester work in solutions of electrolytes? http://youtu.be/w-XbxSiDQWY http://youtu.be/rL1cKb3_ojE http://youtu.be/seSg_GWj1b0

3. Thomson’s Plum Pudding Model • In 1897, the English scientist J.J. Thomson provided the first hint that an atom is made of even smaller particles.

4. Thomson Model • He proposed a model of the atom that is sometimes called the “PlumPudding” model. • Atoms were made from a positively chargedsubstance with negatively charged electrons scattered about, like raisins in a pudding.

5. Thomson Model • Thomson studied the passage of an electric current through a gas. • As the current passed through the gas, it gave off rays of negatively charged particles.

6. Cathode Ray Tube

7. Thomson Model Where did they come from? • This surprised Thomson, because the atoms of the gas were uncharged. Where had the negative charges come from?

8. Cathode Rays Had mass – albeit a very small amount; they pushed a lightweight paddlewheel up an incline. They could do work! Had direction – they passed from the negative to the positive electrode Had charge they bent in an electric field (towards the positive plate) and in a magnetic field Thomson concluded that the negative charges came from within the atom. A particle smaller than an atom had to exist. The atom was divisible! Thomson called the negatively charged “corpuscles,” today known as electrons. Since the gas was known to be neutral, having no charge, he reasoned that there must be positively charged particles in the atom. But he could never find them.

9. Rutherford’s Gold Foil Experiment • In 1908, the English physicist Ernest Rutherford was hard at work on an experiment that seemed to have little to do with unraveling the mysteries of the atomic structure.

10. Rutherford’s experiment Involved firing a stream of tiny positively charged particles at a thin sheet of gold foil (2000 atoms thick)

11. http://chemmovies.unl.edu/ChemAnime/RUTHERFD/RUTHERFD.html • http://chemmovies.unl.edu/ChemAnime/RUTHERFD/RUTHERFD.html

12. Alpha Particles = He nucleus2p+ + 2no • Most of the positively charged “bullets” passed right through the gold atoms in the sheet of gold foil without changing course at all. • Some of the positively charged “bullets,” however, did bounce away from the gold sheet as if they had hit something solid. He knew that positive charges repel positive charges.

13. You Try • The radius of a hydrogen atom is 5 x 10-11 meters. The radius of a single proton is 5 x 10-16 meters. Assuming that atoms take the most size – efficient shape, a sphere, determine how much of an atom is truly empty space free of matter. • Vsphere = 4/3 π r3

14. Rutherford vs Thomson • This could only mean that the gold atoms in the sheet were mostly open space. Atoms were not a pudding filled with a positively charged material. • Rutherford concluded that an atom had a small, dense, positively charged center that repelled his positively charged “bullets.” • He called the center of the atom the “nucleus” • The nucleus is tiny compared to the atom as a whole.

15. Crammin’ Spark You will have a quiz on the correct placement of elements on the table from memory.

17. You Try • The radius of a hydrogen atom is 5 x 10-11 meters. The radius of a single proton is 5 x 10-16 meters. Assuming that atoms take the most size – efficient shape, a sphere, determine how much of an atom is truly empty space free of matter. • Vsphere = 4/3 π r3

18. Rutherford • Rutherford reasoned that all of an atom’s positively charged particles were contained in the nucleus. • The negatively charged particles were scattered outside the nucleus around the atom’s edge.

19. Bohr Model • In 1913, the Danish scientist Niels Bohr proposed an improvement. In his model, he placed each electron in a specific energy level. Where did I put my electrons?

20. Bohr Model • According to Bohr’s atomic model, electrons move in definite orbits around the nucleus, much like planets circle the sun. These orbits, or energy levels, are located at certaindistances from the nucleus.

21. The Wave Model • Today’s atomic model is based on the principles of wavemechanics. • According to the theory of wave mechanics, electrons do not move about an atom in a definite path, like the planets around the sun.

22. Wave Model

23. Electrons are defined by 3-D regions of probability where electrons are found “most” often But where are they when they’re not where we expect?

24. A final word about Mendeleev’s Table… • Mendeleev’s combining powers or valences • Metals do not form compounds with other metals • Metals and non-metals react as do non-metals with non-metals • How? • Why? • Who cares?

25. It’s the electrons, baby!NicAssssscencio • The nucleus does not change. • The number of electrons do change • Atoms become “ions” and they are attracted to oppositely charged particles • Ions are named according to Faraday and his study of electrolytes (salt water) and conduction • The combining powers that Mendeleev found reflect the amount of negative charge lost or gained during a reaction

26. The oxidation numberof an element indicates the number of electrons gained or lost when forming compounds.

27. Elements with positive oxidation numbers lose electrons. (cation)

28. Elements with negative oxidation numbers gain electrons. (anion)

29. +1

30. +2

31. +1, +2, +3

32. +3

33. +4 or -4

34. -3

35. -2

36. -1

37. Electron energy levels, from 1 to 7

38. Electron energy sublevels

39. Electron energy sublevel s

40. Electron energy sublevel p

41. Electron energy sublevel d

42. Electron energy sublevel f

43. How many electrons fit in the 3rd energy level? What about the 4th? Count the boxes to find your answer… 8 3 4 18 Each "pair" of boxes in a sublevel indicates an orbital. Each orbital can hold up to 2 electrons…

44. An Electron Configuration shows the exact location of every electron in an atom. 1s2 2s2 2p6 = Configuration for Neon With very few exceptions, the electron configuration of an atom can be read directly from the Table.

45. S block P block D Block F block

46. Electron Energy Levels Match Up with the Rows of the Periodic Table

47. End Periodic Table Basics

48. Spark Using the oxidation numbers from your periodic table, write the correct formula for compound made of an alkaline earth metal and any p block nonmetal. Explain how the compound forms using electrons

49. Spark Hmmmmm… Think about 2 compounds: Salt aka sodium chloride and The greenhouse gas carbon dioxide Look on the periodic table for the elements and develop instructions for how you think a compound is named. How are the names of elements changed when they make a compound?

50. I think my name is now Nate Nomenclature! Nar, nar ,nar Naming Compounds and Writing Formulas Chemical Nomenclature No men clatechur It is a grown up word!