1. Periodic Table of the Elements Dimitri Mendeleev (1834 - 1907)

2. ElementAt. Weightmp ( o C)D (g/mL)OxideChloride Lithium71800.534Li 2 OLiCl Sodium23980.968Na 2 ONaCl Potassium40630.89K2OK2ORbCl Rubidium86391.53Rb 2 ORbCl Cesium133281.93Cs 2 OCsCl Alkali Metals

3. ElementAt. Weightmp ( o C)D (g/mL)OxideChloride Beryllium912871.85BeOBeCl 2 Magnesium246501.738MgOMgCl 2 Calcium408421.55CaOCaCl 2 Barium1377273.51BaOBaCl 2 Radium(226)7005.5RaORaCl 2 Alkaline Earth Metals

4. Mendeleev’s Periodic Table

6. Mendeleev’s Periodic Table of 1872

7. PropertyEkaaluminumGallium atomic mass6869.72 density (g/cm³)6.05.904 melting point (°C)Low29.78 oxide's formula Ea 2 O 3 (density - 5.5 g cm -3 ) (soluble in both alkalis and acids) Ga 2 O 3 (density - 5.88 g cm -3 ) (soluble in both alkalis and acids) chloride's formulaEa 2 Cl 6 (volatile)Ga 2 Cl 6 (volatile)

8. Light - Wave or Particle Isaac Newton (1643- 1727) Proponent of Light Particles Christiaan Huygens (1629 – 1695) Proponent of Light Waves

9. Key Properties of Wave Behavior Interference Diffraction

10. Young’s Double Slit Experiment

11. Wave Nature of Light

12. Spectrum of White Light

13. Electromagnetic Spectrum

14. Photoelectric Effect

16. EinsteinMillikan

17. Double Slit Experiment Revisited

18. Atomic Spectra HydrogenHeliumNeonMercury

19. Hydrogen Spectrum