The Periodic Table

1. The Periodic Table Chapters 5 and 6

2. Where do elements come from? Galaxies contained only light elements such as H, He, Li, Be, and B immediately after they formed. All the other elements we are familiar with have been synthesized through nuclear fusion taking place in stars. Stars more than 10 times massive than the sun explodes as supernovae at the end of their lives, and ejects newly synthesized elements. Stars of the next generations were formed from the gas that contains these elements. The repetition of these processes eventually leads to the elemental abundance patterns seen in the present solar system.

3. Periodic Table Development • In the early 1800s, scientists began to look for ways to classify the elements. • German chemist Dobereiner grouped elements into “triads”, based on similar properties. • In 1865 English chemist Newlands arranged elements in groups of eight, based on increasing weight. • In1869, Russian chemist Dmitri Mendeleev organized elements into a table based on atomic mass and similar properties. He stated that the properties of elements are a periodic function of their atomic masses (Periodic Law).

4. Mendeleev’s Periodic Table pink = “missing”elements

5. Mendeleev’s Prediction • Mendeleev’s table had several missing elements. When these elements were discovered, they were almost exactly as Mendeleev predicted. • The following is an example of an element that Mendeleev predicted, and we now know as the element Germanium…

6. Germanium is located below silicon. Mendeleev predicted its properties based on its location in his table. Predicted….. Actual……

8. Modern Periodic Law • Henry Moseley revised Mendeleev’s periodic table by using atomic number (rather than atomic mass) to organize the elements. • Atomic number is the basis for our current periodic table.

9. Alternative Periodic Tables Dalton’s Periodic Table

11. SHEET 1 atomic mass atomic number periods valence groups or families

12. REVIEW:MAJOR Groups                                                        < TARGET="disp

13. MAIN GROUPS IN THE PERIODIC TABLE

14. Electron Configuration and the Periodic Table Blocks Sublevel and e- capacity s 2 p 6 d 10 f 14

15. 18 1 2 14 15 16 13 17 B Si 11 3 7 8 10 4 5 6 9 12 noble gases halogens alkali metals As alkaline earth metals Ge Te transition metals Sb post transition metals At p-block d-block s-block inner transition metals f-block

16. He, Ne, Ar, Kr, Xe, Rn H2, N2, O2, F2 Cl2, B, Si, Ge, As, Sb, Te, At Hg, Br2

17. -malleable, ductile, solids -shiny “metallic” surfaces -good conductors (heat/electricity) -tend to give up electrons (form (+) ions in reactions -gases or brittle solids -dull surfaces -good insulators -tend to gain electrons (form (–) ions in reactions Universe Earth’s Crust Human Body Unnilnonium (Meitnerium) Unununium (Roentgenium) Ununnilium (Darmstadtium) Ununquadium

18. Some Periodic Table Jokes An underage Gold atom walks into a bar and sits down. The bartender says “Au!” A neutron walk into a bar and orders a drink. He say, “Thanks, bartender, what do I owe you?” and the bartender replies “No charge!” An atom walks into a bar and says, “hey, know any good jokes about Sodium?” and the bartender says, “Na” An oxygen atom asked potassium out on a date… It went OK. I just told a chemistry joke. There was no reaction. The silicon put his neon the window ledge, climbed out and then krypton along the wall to meet his buddy. I hope the guard cesium before they argon! How often do chemists like to hear jokes? PERIODICALLY. I had a joke about Cobalt, Radon and Yittrium, but its kind of CoRnY. What do you do with a sick chemist? First, you gotta Curium, then you gotta Helium, and if that doesn’t work, then you gotta Barium. What did the bartender say when oxygen, hydrogen, sulfur, sodium, and phosphorus walking into the bar? OH SNaP! I would tell another chemistry joke, but all the good ones Argon.

19. Warm-up: Tantalum Tantalum electrolytic capacitors. The mineral Tantalite, from the Pilbara District, AU.

20. SHEET 2

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22. Atomic Radius • As the principal quantum number (n) increases, the size of the electron cloud increases. So, the size of atoms increases moving down a group. • Atoms in the same period have valence electrons with the same principal quantum number; however, positive charge on the nucleus increases by one proton for each element in a period. This increased nuclear charge pulls the e- cloud in tighter, decreasing atomic radius.

24. 154 = 77 pm 2 77 + 99 pm = 176 pm 198 = 99 pm 2 SMALLER! 130 160 200 215 238 LARGER! 124 114 109 104 100 101

25. Atomic radius vs. atomic number

26. 3p 4p 5p 6p n=2 Why does this trend occur? n=1 • As you move down a group another principal energy level (shell) is added in each row, making atoms larger. • As you move across a period the nuclear charge increases (while energy level remains the same), pulling electrons in closer to the nucleus. n=2 n=3 n=4 n=5

27. What is “effective nuclear charge”? Inner electrons (white) from core shells will “shield” the outer electrons (green), reducing the pull of the nuclear charge. The effective nuclear charge (enc) is the pull the outer electrons as a result of this shielding. Li (enc = 1) Be (enc = 2) B (enc = 3) + + + + + + + + + + + +

28. Cations: (+) become smaller: 1. Reduced the number of energy levels. 2. Positive charged nucleus attracting fewer e-. EX: Anions: (-) become larger: The number of electrons is greater than the nuclear charge (e-s held more loosely). Electrons repel. Radii of ions compared to atoms Cl Na Na+ Cl- Metals Nonmetals

29. Q: What is a cation afraid of? A: A dogion.

30. Trends in Ionic Radius • http://www.mhhe.com/physsci/chemistry/essentialchemistry/flash/atomic4.swf

31. They get larger because more principle energy levels are occupied with electrons (more shells). They get smaller because greater nuclear charge (more protons) pulls the electron cloud closer. They get smaller (b/c empty outer orbitals). They get larger (b/c too many e-s for nucleus). They still get larger because more principle energy levels are occupied. They still get smaller because greater nuclear charge pulls on the remaining electrons… BUT, a huge jump occurs between metals and nonmetals!

32. REVIEW: Atomic Radius • General rule: atomic size increases as you move diagonally from top right corner to bottom left corner. smaller! BIGGER!

33. SHEET 3

34. 520 496 419 403 376 DECREASES 578 787 1012 1000 1251 1521 INCREASES I. E. DECREASES down a group b/c its easier to remove e-s from higher energy levels, farther from the nucleus. I. E. INCREASES across a row b/c its harder to remove e-s from smaller atoms with greater nuclear charge.

35. Patterns in I. E. Which element has the highest I.E.?

36. Ionization energy vs. atomic number

37. Multiple Ionization Energies • Additional e- can be lost from an atom and the ionization energies can be measured. IONIZATION ENERGIES (kilojoules per mole) Element 1st 2nd 3rd 4th 5th H 1312 He 2372 5220 Li 520 7300 11750 Be 900 1760 14850 20900 B 801 2420 3660 25020 32660

38. Mg+ + e- Mg2+ + e- Mg3+ + e- Mg4+ + e- Core electrons are harder to remove than valence electrons. A HUGE jump is seen between the removal of valence vs. core electrons.

39. Warm-up: Tantalum Tantalum electrolytic capacitors. The mineral Tantalite, from the Pilbara District, AU.

40. SHEET 4

41. Mg(OH)2 + H2 NaOH + H2 KOH + H2 Ca(OH)2 + H2 The metals react by losing electrons. This occurs more easily as you move down a group because ionization energy decreases, so metals are more reactive. As you move across a period, metals are less reactive because electrons are more tightly held (higher I.E. going across).

42. REACTIVITY OF MAIN GROUPS IN THE PERIODIC TABLE

43. Alkali Metals Technically, francium (Fr) is the most reactive and least common alkali metal, but since it is highly radioactive with an estimated 550 grams in the entire Earth’s crust at one time, its abundance can be considered zero in practical terms.) • Soft • Very reactive (react with water!) • Always found combined in nature • Form +1 ions • Cesium is the most reactive of the common alkali metals K flame Lithium pellets coated in lithium oxide Lithium and Sodium stored under mineral oil or Ar gas. Cesium

44. Alkaline Earth Metals • Less reactive than alkali metals (react with acid) • Form +2 ions Mg can be used as a fire starter. Due to its small nucleus, Be is highly transparent to X-rays and can be used as a barrier “window” between a vacuum chamber and an x-ray microscope. Radium paint was used in the mid 1900s to paint the hands and numbers of some clocks and watches. The paint was composed of radium salts and a phosphor and glowed in the dark.

45. Transition Metals • Less reactive than groups 1 & 2 • Form ions with a range of charges (+1 to +7) • Many will form complex ions due to incompletely filled d-sublevels. • Complex ions result in colored transition metal solutions. Co glass From left to right, aqueous solutions of: Co(NO3)2 (red); K2Cr2O7 (orange); K2CrO4(yellow); NiCl2 (green); CuSO4 (blue); KMnO4 (purple).

46. Inner Transition Metals Inner Transition Metals • These metals have very similar properties and are difficult to separate. • Found in small quantities in nature. • The Actinium series are all radioactive. uranium A ring of weapons-grade electrorefined plutonium, with 99.96% purity. This 5.3 kg ring is enough plutonium for use in a modern nuclear weapon. Am-241

47. Oxygen Family (Chalcogens) • Oxygen forms compounds easily (with metals and nonmetals) • The rest of this group is less reactive • Nitrogen is most abundant gas in air. Sulfur melts to a blood-red liquid. When burned, it emits a blue flame. selenium Liquid O2

48. CaF2 Halogens • Very reactive nonmetals -F2 reacts with glass! • Form diatomic compounds (Cl2, F2, Br2…) • The only group that exhibits all three states of matter. fluorite Chlorine and fluorine are gases, Bromine is a reddish liquid, and iodine is a grey solid. C4H8Cl2S

49. Noble Gases • Do not react easily • Do not form ions • The non-reactivity is why the gases are called inert • Ar is the most abundant noble gas and is found in Earth’s atmosphere

50. Ligands are nonmetals H2CO3 H2SO4 HNO3 Compounds made from transition metals are often colored. This occurs because d-orbitals are not completely filled with electrons, and electron transitions between these orbitals occur within the visible region of the electro-magnetic spectrum. “Ligands” fill metal d-orbitals with a pair of electrons. Oxygen reacts with many elements! K2CoCl4 CoCl42- Cu(H2O)6Cl2 [Cu(H2O)6]2+ Al(H2O)6Cl3 [Al(H2O)6]3+ K4Fe(CN)6 [Fe(CN)6]4- Carbonate CO32- Nitrate NO3- Sulfite SO32- Hydroxide OH-