Trends in the Periodic Table

1. Trends in the Periodic Table

2. Periodic Trends • In this chapter, we will rationalize observed trends in • Sizes of atoms and ions. • Ionization energy. • Electron affinity.

3. Why is the Periodic Table important to me? • The periodic table is the most useful tool to a chemist. • You get to use it on every test. • It organizes lots of information about all the known elements.

4. PERIODIC LAW • When elements are arranged in order of increasing atom number, their physical and chemical properties show a periodic patter

5. HISTORY OF FORMATION OF PERIODIC TABLE ANTOINE LAVOISIER Late 1790’s French Chemist Compiled a list of 23 known elements. Many of the elements were known to exist since prehistoric times (including Au, Ag, C, O) History

6. History • HISTORY OF FORMATION OF PERIODIC TABLE • By mid-1800’s the known elements was approximately 70. • The discovery of electricity, spectrometer, and the onset of the industrial revolution led to this explosion in the number of elements.

7. History • HISTORY OF FORMATION OF PERIODIC TABLE DMITRI MENDELEEV • 1869 • Russian Chemist • First real periodic table • Combined both Doberiener and Newlands

8. HOW HIS WORKED… Put elements in rows by increasing atomic weight. Put elements in columns by the way they reacted. SOME PROBLEMS… He left blank spaces for what he said were undiscovered elements. (Turned out he was right!) He broke the pattern of increasing atomic weight to keep similar reacting elements together. Dmitri Mendeleev: Father of the Table

9. The Current Periodic Table • Mendeleev wasn’t too far off. • Now the elements are put in rows by increasing ATOMIC NUMBER!! • The horizontal rows are called periods and are labeled from 1 to 7. • The vertical columns are called groups are labeled from 1 to 18.

10. Families on the Periodic Table • Columns are also grouped into families. • Families may be one column, or several columns put together. • Families have names rather than numbers. (Just like your family has a common last name.)

11. Hydrogen • Hydrogen belongs to a family of its own. • Hydrogen is a diatomic, reactive gas. • Hydrogen was involved in the explosion of the Hindenberg. • Hydrogen is promising as an alternative fuel source for automobiles

12. Groups of Elements 1 18 Alkali metals 1 15 Nitrogen group H 1 2 16 He 2 Alkali earth metals Oxygen group or Chalcogen 1 1 2 17 13 14 15 16 17 Halogens Transition metals 13 18 Noble gases Boron group Li 3 Be 4 B 5 C 6 N 7 O 8 F 9 Ne 10 2 2 14 Carbon group Hydrogen Inner transition metals Na 11 Mg 12 Al 13 Si 14 P 15 S 16 Cl 17 Ar 18 3 3 3 8 4 5 6 7 9 11 12 10 K 19 Ca 20 Sc 21 Ti 22 V 23 Cr 24 Mn 25 Fe 26 Co 27 Ni 28 Cu 29 Zn 30 Ga 31 Ge 32 As 33 Se 34 Br 35 Kr 36 4 4 Rb 37 Sr 38 Y 39 Zr 40 Nb 41 Mo 42 Tc 43 Ru 44 Rh 45 Pd 46 Ag 47 Cd 48 In 49 Sn 50 Sb 51 Te 52 I 53 Xe 54 5 5 Cs 55 Ba 56 Hf 72 Ta 73 W 74 Re 75 Os 76 Ir 77 Pt 78 Au 79 Hg 80 Tl 81 Pb 82 Bi 83 Po 84 At 85 Rn 86 * * 6 6 Fr 87 Ra 88 Rf 104 Db 105 Sg 106 Bh 107 Hs 108 Mt 109 W W 7 7 La 57 Ce 58 Pr 59 Nd 60 Pm 61 Sm 62 Eu 63 Gd 64 Tb 65 Dy 66 Ho 67 Er 68 Tm 69 Yb 70 Lu 71 * Ac 89 Th 90 Pa 91 U 92 Np 93 Pu 94 Am 95 Cm 96 Bk 97 Cf 98 Es 99 Fm 100 Md 101 No 102 Lr 103 W

13. He 2 Li 3 Be 4 N 7 O 8 F 9 Ne 10 Na 11 Mg 12 P 15 S 16 Cl 17 Ar 18 K 19 Ca 20 As 33 Se 34 Br 35 Kr 36 Rb 37 Sr 38 Sb 51 Te 52 I 53 Xe 54 Cs 55 Ba 56 Bi 83 Po 84 At 85 Rn 86 Fr 87 Ra 88 Groups of Elements 1 18 H 1 2 13 14 15 16 17 Alkali metals Oxygen family or Chalocogen 1 16 Halogens Alkaline earth metals 17 2 Noble gases Nitrogen family 18 15 Dorin, Demmin, Gabel, Chemistry The Study of Matter , 3rd Edition, 1990, page 367

14. Alkaline Earth Metals • Second column on the periodic table. (Group 2) • Reactive metals that are always combined with nonmetals in nature. • Several of these elements are important mineral nutrients (such as Mg and Ca

15. GROUPS OF ELEMENTS IN PERIODIC TABLE METALS • Vast majority of elements are metals. • Elements found to the left of the heavy black line on periodic table. • Properties that most metals exhibit:

16. GROUPS OF ELEMENTS IN PERIODIC TABLE METALS (cont.) • Physical Properties: • Appearance – high luster • Tapping – malleable • Conductivity – conductor of heat and electricity

17. GROUPS OF ELEMENTS IN PERIODIC TABLE METALS (cont.) • Chemical Properties: • Tend to form positive ions • In HCl – gas produced; corrosion • In CuCl2 - corrosion

18. Metallic Trends in Periodic Table metallic character increases nonmetallic character increases metallic character increases nonmetallic character increases

19. Transition Metals • Elements in groups 3-12 • Less reactive harder metals • Includes metals used in jewelry and construction. • Metals used “as metal.”

20. TRENDS IN PERIODIC TABLE ATOMIC RADII • Definition - distance from nucleus to outer edge of electron cloud of atom • Trend from left to right – decreases • Rationale – increasing nuclear charge • Trend from top to bottom – increases • Rationale – increasing energy levels

21. Carbon Family • Elements in group 14 • Contains elements important to life and computers. • Carbon is the basis for an entire branch of chemistry. • Silicon and Germanium are important semiconductors.

22. Nitrogen Family • Elements in group 15 • Nitrogen makes up over ¾ of the atmosphere. • Nitrogen and phosphorus are both important in living things. • Most of the world’s nitrogen is not available to living things. • The red stuff on the tip of matches is phosphorus.

23. Oxygen Family or Chalcogens • Elements in group 16 • Oxygen is necessary for respiration. • Many things that stink, contain sulfur (rotten eggs, garlic, skunks,etc.)

24. Halogens • Elements in group 17 • Very reactive, volatile, diatomic, nonmetals • Always found combined with other element in nature . • Used as disinfectants and to strengthen teeth.

25. GROUPS OF ELEMENTS IN PERIODIC TABLE NONMETALS • Second most amount of elements. • Elements found to the right of the heavy black line on periodic table. • Properties that most nonmetals exhibit:

26. GROUPS OF ELEMENTS IN PERIODIC TABLE NONMETALS (cont.) • Chemical Properties: • Tends to form negative ions • In HCl – no reaction • In CuCl2 – no reaction

27. GROUPS OF ELEMENTS IN PERIODIC TABLE METALLOIDS • Elements that straddle the heavy black line • Some discrepancy in number(6,7, or 8) • Combination of metallic and nonmetallic properties.

28. GROUPS OF ELEMENTS IN PERIODIC TABLE NOBLE GASES • Elements found in group 18. • Extremely unreactive elements.

29. The Noble Gases

30. The Noble Gases • Elements in group 18 • VERY unreactive, monatomic gases • Used in lighted “neon” signs • Used in blimps to fix the Hindenberg problem. • Have a full valence shell.

31. TRENDS IN PERIODIC TABLE PHYSICAL PROPERTIES (cont.) • Boiling Point • Left to Right – increase through metals then decreases through nonmetals • Top to Bottom – decreases in metals and increase in nonmetals

32. TRENDS IN PERIODIC TABLE REACTIVITY (cont.) • Nonmetals • Trend from left to right – increase • Trend from top to bottom – decrease

33. TRENDS IN PERIODIC TABLE REACTIVITY • Metals • Trend from left to right – decrease • Trend from top to bottom – increase

34. TRENDS IN PERIODIC TABLE CHEMICAL PROPERTIES • Examples: Ionic charge; Reactivity; etc.

35. Factors Affecting Chemical Trends Nuclear Charge – strength of the nucleus The larger the nuclear charge, the stronger the pull on the last electron Sublevel Stability An electron from a full or half-full sublevel requires additional energy to be removed. Shielding effect – electrons between nucleus and outer electron The greater the shielding effect, the less the pull on the last electron. Radius – distance from nucleus to outer electron The greater the distance between the nucleus and the outer electrons of an atom, the less the pull on the last electron. Smoot, Price, Smith, Chemistry A Modern Course 1987, page 189

36. Periodic Trends in Atomic Radii LeMay Jr, Beall, Robblee, Brower, Chemistry Connections to Our Changing World , 1996, page 175

37. TRENDS IN PERIODIC TABLE IONIC RADII • Definition – distance from nucleus to outer edge of ion • Trend for more positive ion – decreases • Rationale – increasing relative nuclear charge • Trend for more negative ion – increases • Rationale – decreasing relative nuclear charge

38. 1 2 3 5 6 7 N3- Li1+ Be2+ O2- F1- 1.71 1.40 1.36 0.60 0.31 Na1+ Mg2+ S2- Cl1- Al3+ 0.95 0.65 0.50 1.84 1.81 Se2- Br1- Ga3+ K1+ Ca2+ 1.33 0.99 0.62 1.98 1.85 Te2- I1- In3+ Rb1+ Sr2+ 0.81 2.21 2.16 1.48 1.13 Tl3+ Cs1+ Ba2+ 1.69 1.35 0.95 = 1 Angstrom Periodic Trends in Ionic Radii IONIC RADII

39. Group 13 e e e e e e e e e Li Li+ F1- F 64 152 60 136 Na Na+ Al Cl1- Cl 50 95 143 99 186 181 K K+ Br-1- Br 114 133 195 227 Trends in Atomic and Ionic Size Metals Nonmetals Group 1 Group 17 Al3+ Cations are smaller than parent atoms Anions are larger than parent atoms

40. Fluorine is the most electronegative element

41. e e Li Li+ Li 152 60 Li+ 60 Lithium atom Energy e e Li Li + e Lithium ion Lithium atom Lithium ion

42. TRENDS IN PERIODIC TABLE FIRST IONIZATION ENERGY • Definition – amount energy needed to remove the outer most electron • Trend from left to right – increases • Rationale – increased nuclear charge • Trend from top to bottom – decreases • Rationale – increased energy levels and shielding effect

43. TRENDS IN PERIODIC TABLE ELECTRON AFFINITY • Definition – the attraction of an atom for an electron • Trend from left to right – increases • Rationale – increasing nuclear charge • Trend from top to bottom – decreases • Rationale – increasing energy levels and shielding effect

44. TRENDS IN PERIODIC TABLE ELECTRONEGATIVITY • Definition – the tendency of an atom to attract electrons to itself when it is combined with another atom • Trend from left to right – increases • Trend from top to bottom – decreases

45. Summary of Periodic Trends Shielding is constant Atomic radius decreases Ionization energy increases Electronegativity increases Nuclear charge increases 1A 0 Nuclear charge increases Shielding increases Atomic radius increases Ionic size increases Ionization energy decreases Electronegativity decreases 5A 2A 3A 4A 6A 7A Ionic size (cations) Ionic size (anions) decreases increases

46. H 2.1 Li 1.0 Be 1.5 B 2.0 C 2.5 N 3.0 O 3.5 F 4.0 Na 0.9 Mg 1.2 Al 1.5 Si 1.8 P 2.1 S 2.5 Cl 3.0 K 0.8 Ca 1.0 Sc 1.3 Ti 1.5 V 1.6 Cr 1.6 Mn 1.5 Fe 1.8 Co 1.8 Ni 1.8 Cu 1.9 Zn 1.7 Ga 1.6 Ge 1.8 As 2.0 Se 2.4 Br 2.8 Rb 0.8 Sr 1.0 Y 1.2 Zr 1.4 Nb 1.6 Mo 1.8 Tc 1.9 Ru 2.2 Rh 2.2 Pd 2.2 Ag 1.9 Cd 1.7 In 1.7 Sn 1.8 Sb 1.9 Te 2.1 I 2.5 * Cs 0.7 Ba 0.9 La 1.1 Hf 1.3 Ta 1.5 W 1.7 Re 1.9 Os 2.2 Ir 2.2 Pt 2.2 Au 2.4 Hg 1.9 Tl 1.8 Pb 1.8 Bi 1.9 Po 2.0 At 2.2 y Fr 0.7 Ra 0.9 Ac 1.1 * Lanthanides: 1.1 - 1.3 y Actinides: 1.3 - 1.5 Below 1.0 2.0 - 2.4 1.0 - 1.4 2.5 - 2.9 1.5 - 1.9 3.0 - 4.0 Electronegativities 1A 8A 1 1 3A 5A 7A 2A 4A 6A 2 2 3 3 2B 4B 6B 8B 1B 3B 5B 7B Period 4 4 5 5 6 6 7 Hill, Petrucci, General Chemistry An Integrated Approach 2nd Edition, page 373