1. Mendeleev’s Role Organization and discovery Organization and discovery

2. Periodic table history John Newland 1800’s Law of octaves. 63 elements Law of octaves – elements group in 8’s because they repeated the Same number of valence electrons

3. ► Dmitri Mendeleev ► 2nd person to work on Periodic table ► Notice that elements didn’t Go together – some react violently ► Arranged by atomic Mass

4. ► Henry Mosley ► group them by atomic number and they would have a better pattern/flow ► Physical and chemical properties are functions of the atomic #

5. ► Periodic law- elements with similar properties occur in a regular pattern - Elements are arranged by increasing atomic number - Certain properties reoccur - Predictions can be made

6. Organization of the PT ► Rows go from left to right  They are called periods  Different properties  Valence electron increase.  Oxidation number changes

7. Organization of the PT ► Columns go up and down  They are called families or groups  There are 18 diff families