The Evolution of the Periodic Table: From Triads to Modern Trends

1. Chapter 6 Periodic Table World of Chemistry Harry potter sings the element song

2. Periodic Table • a chart that organizes information about the elements • knowing an elements location in the table allows you to predict properties • scientists have placed elements with similarities in the same groups on the table

3. History: Joseph Dobereiner – Triads (1829) • made chart of groups of three elements that had similar properties • ex. Ca, Ba, Sr (found Sr mass is half way between the other two)

4. Dobereiner’s Triads

5. John Newlands – Law of Octaves (1863) • arranged in order of atomic mass • appeared to be a repetition of properties every eighth element • arranged elements into groups of 7 • Law of Octaves – same properties repeat every 8th element  • (but it didn’t account for Noble gases and transition metals)

6. Law of Octaves 1 2 3 4 5 6 7 Li Be B C N O F Na Mg Al Si P S Cl K

7. Song-elemental Funkiness Mendeleev’s Periodic Table 1869- Dmitri Mendeleev and Lothar Meyer both demonstrated a connection between atomic mass and properties -Mendeleev published his table first and better demonstrated its usefulness Video

9. -placed elements with similar properties in vertical columns called groups or families -horizontal rows are periods -if no known element fits in a particular place, he left a blank (predicted the properties of it for someone to discover later)

10. Ekasilicon (Es) (predicted properties) Atomic Mass: 72 High Melting Point Density: 5.5 g/ml Dark gray metal Will obtain from K2EsF6 Slightly dissolved by HCl Will form EsO2 Density of EsO2: 4.7 g/ml Germanium (Ge) (1886) (actual properties) Atomic Mass: 72.61 Melting Point: 945° C Density: 5.323 g/ml gray metal Will obtain from K2GeF6 Not dissolved by HCl Will form GeO2 Density of GeO2:4.7 g/ml Mendeleev’s Prediction

11. Mendeleev’s Periodic Law • physical and chemical properties of elements were periodic functions of their atomic mass • by arranging by atomic mass he did find he had some elements in groups with different properties (ex. Te and I, Co and Ni)

12. Modern Periodic Table -Henri Moseley’s discovery of the atomic number corrected Mendeleev’s problems and led to the modern table

13. Modern Periodic Law • properties of elements are periodic functions of their Atomic numbers • found atoms of similar electron configurations found in similar groups • The Development of the Periodic Table

15. Chinese Periodic Table

16. German Table (Periodensystem der Elemente )

18. Russian

19. Tableau de classification périodique des éléments Métaux alcalins E Symbole Métaux alcalino-terreux Élément Nom Métaux de transition Z Numéro atomique Semimétaux Nombre de neutrons N A Masse atomique Métalloïdes Hydrogène Non-métaux Lanthanides Gazes rares Actinides Non-catégorisé

20. Norwegian • http://no.wikipedia.org/wiki/Periodesystemet_i_stor_utgave • Romanian

21. Parts of the Periodic Table Groups or Families - vertical column of elements w/ similar properties Elemental Funkiness

22. Group 1- Alkali Metals Group 2 – Alkaline Earth Metals Group 16- Chalcogens Group 17 – Halogens Group 18 – Noble or Inert gases 3-12 – Transition metals Staircase- metalloids Bottom rows- Rare earth metals (Lanthanoids & Actinoids or Lathanides & Actinides)

24. Periods - horizontal rows (of elements w/ common outer energy level)

25. Properties of Elements Metals: -left side of staircase -hard, shiny, conduct heat or electricity well, malleable, ductile -have 3 or fewer electrons in outer level (3 or less dots in dot diagram)

26. Nonmetals -right side of staircase -gases or brittle solids, dull surfaces, used as insulators -have 5 or more electrons in outer energy level

27. Metalloids -have properties of both metals and non metals -found on staircase Reading the Periodic Table

28. Organizing elements by electron configuration • Atoms in same group have similar chemical properties because they have similar electron configurations and similar # of valence electrons • Period numbers  tell us the outer most energy levels • The periodic table not only has rows & columns but sections or blocks representing the sublevels

29. Outer energy levels 1 2 3 4 5 6 7 s - block p - block d - block f -block

30. The energy level number in front of (s) is always the period number • The energy level number in front of the (p) is the period number • The energy level number in front of the (d) is one less than the period number • The energy level number in front of the (f) is 2 less than the period number

33. Periodic Trends • Properties of elements change in predictable ways depending on their location on the periodic table because of their electron configuration

34. Atomic Radius -half the distance between adjacent nuclei in two atoms of the element bonded together

35. Trends:

36. Ionic Radius • when elements lose or gain electrons to form ions their size increase and decreases • an atom that loses electrons and becomes positively charged gets smaller • an atom that gains electrons and becomes negatively charged gets larger

38. Trends: Positive ions decrease Negative ions decrease Generally decreases

39. Ionization Energy -energy required to remove an electron from a gaseous atom

40. Trends:

41. Electronegativity • the relative ability of the atoms to attract electrons in a chemical bond

43. Electronegativity Trends:

44. Chemical Reactivity • Tendency of a substance to undergo a chemical change • Metals- reactivity increase moving towards bottom left (Cesium) • Nonmetals- reactivity increase moving towards top right (fluorine)

45. Quest • 16 multiple choice • 3 going from element to configuration • 7 going from configuration to name • Short answer- id elements as metal/non/metalloid, and the group name • Know: History (Triads, octaves, Mendeleev), Modern periodic law=atomic mass, trends, families)