1. Drill – 11/17 1.What determines how the periodic table is arranged? 2.What does “periodic” mean?

2. The Periodic Table

4. Dmitri Mendeleev was the first to organize the elements according to their atomic mass & their properties. He observed that when elements were arranged by increasing atomic mass, similarities in properties occurred at regular intervals…called periodic. The periodic table was born.

5. Henry Moseley later modified Mendeleev’s table by organizing the elements by atomic number rather than atomic mass.

6. Who told the elements where to go????

7. Periodic Law The physical and chemical properties of the elements appear at regular intervals (periodic) when arranged by atomic number.

8. The rows on the periodic table are called periods. How many periods are there? The columns on the periodic table are called families or groups. How many families are there?

9. http://library.thinkquest.org/06aug/00318/I mages/periodic_table.gif

10. Valence Electrons Electrons in the outermost energy level (our outer shell) Example: How many valence electrons are in Aluminum? 1. Write the configuration. 2. Find the highest energy level 3. Count the electrons in all sublevels.

11. How many valence electrons? 1.Lithium 2.Sodium 3.Tin 4.Carbon

12. Lewis Dot Diagrams Use dots around symbol to represent valence electrons. Start on the right side of symbol and go clockwise around symbol once before paring up. Ex. Nitrogen ___ valence electrons N ● ● ● ● ● 5