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Chemical Periodicity? What?

Chemical Periodicity? What?. Periodicity. When elements are organized in order of  atomic mass , and grouped by similarities of chemical properties , a certain “ pattern ” or periodicity of properties becomes evident. Draft for first version of Mendeleev's periodic table

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Chemical Periodicity? What?

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  1. Chemical Periodicity?What?

  2. Periodicity • When elements are organized • in order of  atomic mass, and • grouped by similarities of chemical properties, • a certain “pattern” or periodicity • of properties becomes evident Draft for first version of Mendeleev's periodic table (17 February 1869).

  3. Review of the Periodic Table

  4. Group IA – alkali metals Review of the Periodic Table

  5. Group IA – alkali metals H1 - 1s1 Li3 - 1s22s1 Na11 - 1s22s22p63s1 K19 - 1s22s22p63s23p64s1 Rb37 - 1s22s22p63s23p63d104s24p65s1 Cs55 - 1s22s22p63s23p63d104s24p64d105s25p66s1 Fr87 - 1s22s22p63s23p63d104s24p64d104f145s25p65 d106s26p67s1

  6. Group IIA – alkaline earth metals Review of the Periodic Table

  7. Group IIA – alkaline earth metals Be4 - 1s2 2s2 Mg12 - 1s22s22p63s2 Ca20 - 1s22s22p63s23p64s2 Rb38 - 1s22s22p63s23p63d104s24p65s2 Cs55 - 1s22s22p63s23p63d104s24p64d105s25p66s2 Fr87 - 1s22s22p63s23p63d104s24p64d104f145s25p65 d106s26p67s2

  8. Group VIII – Noble Gases Review of the Periodic Table

  9. Group VIII – Noble Gases He2 - 1s2 Ne10 - 1s22s22p6 Ar18 - 1s22s22p63s23p6 Kr36 - 1s22s22p63s23p63d104s24p6 Cs54 - 1s22s22p63s23p63d104s24p64d105s25p6 Rn86 - 1s22s22p63s23p63d104s24p64d104f145s25p65 d106s26p6

  10. Group VII – Halogens Review of the Periodic Table

  11. Group VII – Halogens F9 - 1s22s22p5 Cl17 - 1s22s22p63s23p5 Br35 - 1s22s22p63s23p63d104s24p5 I53 - 1s22s22p63s23p63d104s24p64d105s25p5 At85 - 1s22s22p63s23p63d104s24p64d104f145s25p65 d106s26p5

  12. Review of the Periodic Table Group VI

  13. Group VI O8 - 1s22s22p4 S16 - 1s22s22p63s23p4 Se34 - 1s22s22p63s23p63d104s24p4 Te52 - 1s22s22p63s23p63d104s24p64d105s25p4 Po84 - 1s22s22p63s23p63d104s24p64d104f145s25p65 d106s26p4

  14. Electron’s Role in Chemical Behavior • Atoms are most stable when their outermost “s” and “p” subshells are filled. – “the rule of 8” • Electron’s in the outermost shell determine chemical reactivity

  15. Periodic Table and e- config. 1 2 3 4 5 6 7 Increasing energy level (shell) px1 py1 pz1 px2 py2 pz2 s1 s2 Increasing energy sublevel (subshell)

  16. Periodic Patterns - Atomic Radii 2r

  17. Atomic Radii

  18. Periodicity and Atomic Radius • In group: • atomic radius increases as you move down the column • Across period: • Atomic radius decreases as you • Move from left to right • Rationale: • group – adding outermost electron shell • row –  pulling in with  nuclear charge

  19. Ionic Radius 97pm vs 181pm 190pm vs 102pm

  20. Periodic Patterns and Ionic Radius • In group: • ionic radius increases as you move down the column • Across period: • Ionic radius is max in group 5 • Lower on left and right • Rationale: • group –outermost shell • row – transition between losing and gaining electrons to reach stability

  21. Ionic Radius

  22. Periodic Patterns and Ionization Energy • Ionization energy ≡ energy needed to remove an electron from an atom or ion • first ionization energy - energy needed to remove an electron from a neutral atom • second ionization energy - energy needed to remove a second electron from a positively charged ion

  23. Ionization Energy

  24. Periodic Patterns and Ionization Energy • In group: • ionization energy  as you move down the column • Across period: • Ionization energy  as you move from left to right • Rationale: • group –outermost shell electrons • farther away from nucleus • row – outermost electron more tightly • held

  25. Ionization Energy

  26. Periodicity and Electronegativity • Electronegativity ≡ a measure of how tightly held an electron is.

  27. Electronegativity

  28. Periodicity and Electronegativity • In group: • electronegativity  as you move down the column • Across period: • Electronegativity  as you move from left to right • Rationale: • group –atoms more willing to accept another electrons due to  nuclear charge and shielding • row – atoms move closer to completed “s” and “p” orbitals and stability

  29. Electronegativity

  30. Periodic Trends – Summary Decreasing Atomic Radii Decreasing Ionic Size Increasing Ionization Energy Increasing Electronegativity Increasing Atomic Radii Increasing Ionic Radius Decreasing Ionization Energy Decreasing Electronegativity

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