The document discusses the periodic table, its history, organization, and the trends in various elemental properties that can be predicted from it. The periodic table was developed by Mendeleev in 1869 and organizes elements by atomic number. It allows prediction of trends in properties like atomic radius, ionization energy, and electronegativity across periods and down groups. The periodic table classifies elements as metals, nonmetals, metalloids and noble gases and notes important families like alkali metals, alkaline earth metals, and halogens.

1. The Periodic Table

3. Dmitri Mendeleev (1869) In 1869 Mendeleev and Lothar Meyer (Germany) published nearly identical classification schemes for elements known to date. The periodic table is base on the similarity of properties and reactivities exhibited by certain elements. Later, Henri Moseley ( England,1887-1915) established that each elements has a unique atomic number, which is how the current periodic table is organized. http://www.chem.msu.su/eng/misc/mendeleev/welcome.html

8. THE PERIODIC TABLE

10. 3. Trend in Ionization Energy Ionization energy: The energy required to remove the valence electron from an atomic specie.

11. 4. Trend in Electron Affinity Electron affinity is a measure of the energy that is released when an atom acquires an electron. We say that the more energy is released, the more readily the atom becomes an anion.

13. Summary of Trend