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Understanding the Periodic Table: History, Trends, and Vocabulary

Explore the origins of the Periodic Table with the Greeks and Romans, early classification methods, key elements like the Law of Octaves, parts of the table, families, classes of elements, special metals, vocabulary, and important trends like atomic radius, reactivity, and more.

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Understanding the Periodic Table: History, Trends, and Vocabulary

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  1. Periodic Table

  2. Chemistry is believed to have its origin with the Greeks and the Romans. • Classification began early.

  3. Trends in the Periodic chart • Dobereiner—1817 • Classified 3 related elements----Triad • He used Ca Ba Sr

  4. Newland---1863 • Arranged elements by mass & realized that a pattern developed every 8th element: this is the Law Of Octaves

  5. Octet Rule: • elements with 8 e- in the outer energy level will be MOST stable and unreactive

  6. Parts of the Periodic Table • Rows/periods -7 • Groups/families ---18 • or • 1A, IIA, IIIA, IVA, VA, VIA, VIIA, VIIIA • IB, IIB, IIIB, IVB, VB, VIB, VIIB, VIIIB

  7. Periodic Table • Row(Period)—horizontal arrangement of elements on the chart • Group (Family)---vertical arrangement of elements on the chart—elements in the same family will have similar properties

  8. Families • Alkali metals----Group 1 • Alkaline earth metals---Group 2 • Chalcogens---oxygen family group 16 • Halogens---group 17 • Inert or Noble Gas----group 18 • Transition metals –3-12 • Rare earth metals –lanthanoid & actinoids

  9. Special PeriodsInner Transition Metals • Lanthanoid Series---58-71 • Actinoid Series---90-103

  10. Classes of Elements • Metals-- (left of zig/zag line) • Most are solid • Conduct electricity/heat well • Lose electrons to form + cations • Malleable ( can be bent into shapes) • Ductile ( can be pulled into a wire)

  11. Classes of elements • Non-metals--- to the right of zig/zag line • Liquids and gases • Gain electrons to form negative anions • Poor conductors • Brittle

  12. Classes of elements • Metalloids---lie exactly to left or right of the zig/zag line. Have properties of both metal and non-metals • Semi-conductors or insulators • Semi-metals

  13. Special metals • Transition metals— • Groups 3-12 • Multiple oxidation states • Hardest metals known • Elements with electrons in “d” orbitals

  14. Vocabulary • Valence electrons---electrons in the outer shell of an atom. • Group # #valence e- • 1 1 • 2 2 • 13 3 • 14 4 • 15 5 • 16 6 • 17 7 • 18 8 (except He)

  15. Representative Elements ( Main Group )----Groups 1,2, 13-18 • Oxidation state--- created by number of electrons lost or gained

  16. Vocabulary • Inert Gases or Noble Gas— • Have filled outer shells and are unreactive • “p” orbitals are full

  17. chart • Group oxidation number • 1 +1 • 2 +2 • 13 +3 • 14 + or – 4 • 15 -3 • 16 -2 • 17 -1 • 18 0

  18. As the Periodic Table began to take shape certain “trends” became apparent: • Size of atom (atomic radius) • Density • Metallic Character • Reactivity • Electronegativity • E-affinity • Ionization energy • Shielding effect

  19. Atomic radius: • Down a group----I (due to e- levels) • Rt to left on row----I (due to # of p+ ) • Ion size: • Anion(neg) > neutral • Cation(pos) < neutral

  20. Density • Down a group ----I • No trend for row

  21. Metallic Character • Down a group -----I • Rt to Left on row ----I

  22. Reactivity: • Down a group ---I ( metallic ) • Up a group -----I ( non-metallic) • The MOST reactive metal is Francium • The MOST reactive non-metal is Fluorine • No row trend

  23. Electronegativity---an attraction an atom for a “shared pair” of e- • Electronegativity --- • Down a group ---D (due to #e- levels) • Lt to rt on row----I (due to #p+ )

  24. Electron Affinity– attraction of atom for an electron • E- - affinity - • Down a group ---D • Lt to rt on row ---I

  25. Ionization energy ---energy needed to remove an e- from a neutral atom • Ionization energy— • Down a group ---D ( because of # e- levels) • Lt to rt on a row---I (due to # P+ )

  26. Shielding effect—decrease in the attraction between outer e- and the nucleus due to the presence of other e- between them • Shielding effect: • Down a group –I • Lt to right on row ---- same

  27. When using trend rules to answer a question, remember: • A) ask are these atoms in same row or same group • B) what is the trend for that property for a)a row or for a b) group

  28. Which is smallest from the following; • Si Pb Sn C

  29. Which is largest? • F B N Ne

  30. Which has the highest electronegativitiy? • Na Cl Ar Al

  31. Which has the lowest electronegativity? • Sb N As P

  32. Which has the highest ionization energy? • N C Li Ne

  33. Which has the lowest ionization energy? • Zn Hg Cd

  34. Which has the greatest shielding? • Ne Xe Ar He

  35. Which has the greatest amount of shielding? • S Al Ar Na

  36. Which atom has highest e-affinity? • K Li Fr Na

  37. Which atom has the smallest e-affinity? • Pb C Sn Si

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