1. Ch 5 The Periodic Law 5.1 History of the Periodic Table
Mendeleev
Proposed/arranged elements into rows based on increasing mass (like periods) and into columns due to similar properties (like groups)
Prediction, not all elements discovered yet
Left spaces for new elements!

2. Mosley
Working with Ernest Rutherford and spectra of metals
Saw arranged by increasing nuclear charge, p+
Led to atomic number (not atomic mass) to organize periodic table
Periodic Law: elements arranged in order of increasing atomic number, there is a periodic repetition of physical/chemical properties

3. Noble Gases (18 or 8A, full p)
Added to periodic table, missed because unreactive
Lanthanides (4f)
14 elements atomic # 58-71
Added in 1900s
Actinides (5f)
14 elements atomic #
Belong in pd 6-7 and groups 3-4, but placed below periodic table
Periodicity
Arrangement of e- around nucleus

4. 5.2 E- Configuration and the Periodic Table
Recall e- configurations/shapes
See pattern of e- configuration in periodic table!

5. s- orbital Alkali: Group 1 or 1A Alkaline earth metals: Group 2 or 2A
From Arabic al aquali= the ashes
Metals with 1e-
Highly reactive metals
Alkaline earth metals: Group 2 or 2A
Harder/denser with 2e-
Still reactive
H and He: s-block but gases/ do not share properties

6. d- block elements Transition metals: Group 3-12 (B group elements)
Metals 80% periodic table
Properties: good conductors heat/electricity, reflect light with luster/sheen, ductile, malleable

7. p-block: Group 13-17 or 3A-7A Main- group elements
Non metals or metalloids
Halogens: Group 7A or 17 are the most reactive non-metals
Noble gas: Group 18 or 8A are the most stable elements

8. f-block Inner transition metals Below main body of periodic table 14e-
Previously called rare-earth metals (misleading bc more abundant than other elements)
Lanthanides
Actinides

9. 5.3 E- Configuration and Periodic Properties
Atomic Radii: ½ distance between nuclei of identical bonded atoms
Period: decreases as move from left to right in period
Group: increases as move down group
Same for atomic size!!!

10. Ionization: Energy to remove e-
Period: increases from left to right in period
Group: decrease from top to bottom in group

11. Electron affinity: E added when an e- is added to neural atom; energy given off is neg #
Period: most periods except halogens gain e-; decreases left to right
Group: added with greater difficulty down a group usually, increases down group

12. Ionic radii: cations are smaller, anion are larger
Period: cations/anions decrease in size from left to right in period
Group: increase in ionic radii from top to bottom in group

13. Electronegativity: how easy to attract e-
Period: increases from left to right in a period
Group: decrease from top to bottom in a group