1. Trends in the Periodic Table trend: direction or pattern p. 70-75

2. s, p, d and f blocks of the periodic table

3. groups periods “ Long form ” periodic table

4. Electronic structures are related to the position of the elements on the periodic table –s-block: s orbitals are filled –p-block: p orbitals are filled, etc.

5. Zumdahl p. 322

7. Atomic number Increases from left to right (across periods) Increases from top to bottom (down groups)

8. Period number: number of energy levels containing electrons Group: same valence shell electron configuration 1 2 3456789 10 1112 1314151617 18

9. Group names 1: alkali metals (1 valence electron) 17: halogens (7 valence electrons) 18: noble gases (all electron shells filled, little chemical reactivity) periodicity: repeating of similar properties because of similar valence electron configuration

10. 1 17 18 Important Groups

11. Physical Properties in the PTE

12. Atomic and Ionic Radii Atomic radius: half the distance between the nuclei of two touching atoms Increases going down a group –Additional filled energy levels of electrons Decreases going across a period –More electrons = increased attraction to positive nucleus

13. Increasing Atomic Radius

15. Atomic Radius Increases

17. Radius of an atom always decreases when it loses an electron (becomes a cation +) –A whole energy level may be lost, or –There is less electron-electron repulsion (pushing away) between the electrons in different energy levels The radius of an atom always increases when it gains an electron (becomes an anion -) –Increased electron-electron repulsion pushes the valence shell away from the nucleus.

18. Ionic radius examples K K + Cl Cl -

19. Ionization energy The amount of energy that is required to remove an electron from a gaseous atom Decreases going down a group –Valence electrons are further from the nucleus, less “pull” from the protons

20. - +15 - -- - - - - - - - - - - - +13 +5 Effective Nuclear Charge Charge exerted on each electron by the positively charged nucleus - +15 - -- - - - - - - - - - - - +13 +5

21. Ionization Energy Increases going across a period –Electrons on the same energy level are more strongly “pulled” by the nucleus (which is increasing in positive charge) +11 +12

23. Ionization Energy Increases

25. Electronegativity How strongly an atom attracts other electrons in a chemical bond (electron affinity) Decreases going down a group –Valence electrons are further from the nucleus, less “pull” from the protons –Atoms increase in radius Increases going across a period –Electrons on the same energy level are more strongly “pulled” by the nucleus –Atoms decrease in radius

27. Electronegativity Increases

28. Other Physical Properties Melting Point Boiling Point Density Types of bonds formed

31. Chemical Properties

32. Elements in the same group have similar chemical properties

33. Increasing atomic and ionic radii Increasing ionization energy Increasing electronegativity Increasing reactivity

34. Alkali metals Soft, malleable (can be shaped) metals Low melting points –Can only contribute one electron to a bond – easily broken Low density –Largest atomic radius in the period Very chemically reactive –One valence electron, easily lost, + ion Tarnish quickly Combine with O, Cl, Br to form ionic compounds

35. sodium potassium rubidium cesium (l)

36. All react with water to form a solution of metal hydroxide and hydrogen 2M(s) + 2H 2 O(l)  2M + (aq) + 2OH - (aq) + H 2 (g) M = alkali metal sodium potassium Reaction is alkaline (base)

39. What trend in reactivity did you see as we moved down the group?

40. Increasing atomic and ionic radii Increasing ionization energy Increasing electronegativity Increasing reactivity

41. Halogens Very reactive non-metals –Need only one electron to fill valence shell All exist as diatomic molecules –Cl 2, Br 2, I 2 (all colored) Slightly soluble in water – non-polar bonds

42. Halogens – colored diatomic molecules fluorinepale yellow gas chlorineyellow-green gas brominered-brown liquid iodine black-purple solid purple gas

43. X 2 (aq) + H 2 O(l)  H + (aq) + X - (aq) + HOX(aq) –X = halogen –HOX = acid Ex: Chlorine: HOCl (HClO: chloric acid), used as a bleach, toxic to microbes, treats water

44. all quite electronegative (high electron affinity) easily gain electrons to form anions –halide ions Ability to gain electrons decreases going down a group reactivity decreases going down a group

45. Halogens combine with metals to produce ionically bonded salts containing a halide ion. –white and soluble in water  colorless solutions –insoluble: lead and silver compounds yellow –lead(II) iodide: bright yellow precipitate

46. Test for a halide ion by adding nitric acid, then a solution of silver nitrate –a precipitate indicates Cl-, Br-, or I- compoundcolor AgFno precipitate AgClwhite, then purple/black in sunlight AgBroff-white AgIpale yellow

47. silver bromide used to print black and white photos silver chloride used to print black and white photos silver iodide used to “seed the clouds” to make it rain

48. Oxidant: In a reaction, a higher halogen will replace a lower halogen. NaCl(aq) + Br -  NaBr(aq) + Cl -  NaCl(aq) + Br - (aq)

49. Ionization Energy Increases Atomic Radius Increases Electronegativity Increases Metallic Character Increases

50. Your questions… Answered!

51. Q: Why don’t the electrons crash into the nucleus? A: Electrons have lots of their own energy. E=hf due to their position around the nucleus. Electrons are constantly moving, very fast. This kinetic energy overcomes the positive attraction of the nucleus.

52. A: How does temperature affect ionization energy? Q: Temperature has no affect on ionization energy. Heat is only powerful enough to change kinetic energy of a particle or molecule. Microwaves and radio waves can affect nuclear spin. Gamma rays and X rays can effect the nucleus and the inner electrons. Electricity does have an affect on ionization energy.

53. Q: How does temperature affect the movement of the subatomic particles, specifically electrons? A: Temperature does not have enough energy to affect subatomic particle movement, only molecule movement.

54. Q: Where does ionization energy come from? A: Electricity

55. Q: If there is just one electron in a p x orbital, can it be located everywhere, or just on one side of the orbital? A: It can be located anywhere. An orbital is an area of probability inside of which the electron will be found. Electrons are constantly moving very fast, and can be anywhere within their orbitals.

56. Q: Why does ionization energy increase going across a period? Why, oh Why?!? A: The effective nuclear charge DOES change on each valence electron! +11+12 ENC=+1 ENC=+2

58. Mid-term Tuesday, April 22 –14:40-16:10 –Room 407 or 408 19 questions – short answer or calculations –2 definitions Answer all parts of all questions No dictionary/translator Bring calculator, Periodic Table on test