1. Chapter 5 sec 1 The Periodic Table -Organizing the Elements

2. Searching for an Order Until the 1750’s scientists had only identified 17 elements. What were they mainly? Metals  Copper, Iron French Chemist Antoine Lavoisier grouped the elements into categories Metals, Nonmetals, Gases, Earths

3. Searching for an Order After 80 years, of trying to group elements, Russian Chemist discovered a system Dmitri Mendeleev Proposal: Modeled after his favorite Card game, Solitaire Each Element was given a “card” He then watched how elements reacted to hydrogen and Oxygen

4. Mendeleev Arranged elements in  atomic mass. Periodic properties repeating properties of physical & chemical properties. Periodic Table: Arrangement of elements in columns, based on set properties that repeat row to row

5. Mendeleev’s Table

6. Mendeleev Prediction: Not full table, too many undiscovered elements Had to leave 4 spaces between Bromine & Zinc Only had Arsenic & Selenium to fill Left spaces Evidence: Close match between predictions and properties of elements showed value for the table