2. Chp 5: The Periodic Table A Brief Intro

3. Table History First tables (1866-1873) by Dmitri Mendeleev arranged elements by similar properties & atomic weight

5. 1914 Modern periodic table by Henry Mosely used atomic number to order 18 groups 7 periods

6. Elements Metals Nonmetals Metalloids In groups (18) and periods (7)

7. Main Groups (A) 1,2, 13-18 Group 1: Alkali metals (p 786) -most reactive metals, soft, shiny, 1 valence e- Group 2: Alkaline Earth Metals (p792) –Harder, stronger than group 1, slightly reactive, 2 valence e-

8. G13 G14 G15 G16 p808 p812 p828 p832 Group 17: Halogens (p 838) –Most reactive nonmetals, name means “salt former”, 7 valence e- Group 18: Noble Gases –Very stable nonmetals, all other elements want their e- structure, 8 valence e-

9. Transition Groups (B) 3-12 & 2 series Transition Metals 3-12: (p 798) -d-block metals, valence e- vary Lanthanide + Actinide series: -f-block metals, valence e- vary, some man-made and radioactive

10. Periodic Trends Compound formation

11. Trend Reasons and Forces Nuclear Charge – the more positive charge, the more it attracts electrons closer Nuclear Shielding – inner shell electrons repel outer shell electrons Number of electron shells – distance from the nucleus Ion charges change the size of the atom, positive ions = smaller negative ions = larger

12. Atomic Radius Half the distance between the nuclei of 2 identical atoms Electronegativity the ability of an atom to attract electrons to itself. Basic Properties

13. Ionization Energy ( + ) energy required to remove electrons Electron Affinity ( - ) energy change from adding electrons (Group 2,12,18 do not follow the trend, have no e- affinity)

14. Insert figure 7.7 Relative Size of Atoms