1. Topic: The Periodic Table PSSA: 3.4.7.A/S8.C.1.1

2. Objective: TLW describe the design and structure of the Periodic Table and predict properties of elements based on their location on the table.

3. MI #1: Mendeleev and the PT Mendeleev arranged elements in order of increasing atomic mass. Atomic mass is the average mass of all of the isotopes of an element.

4. MI #2: Valence Patterns When arranged by increasing atomic mass, a pattern in the valences is found. Valence is the # of electrons gained, lost, or shared during bonding. Valence = 1 2 3 4 3 2 1 0 # of valence e - = 1 2 3 4 5 6 7 8 Elements in the same column have the same valence and similar properties.

5. MI #3: Moseley and the PT Henry Moseley determined the atomic number of each element. When he arranged elements by atomic #, they fell into columns with the same valence and similar properties without exception.

6. MI #4: Design of the PT (Columns) Each column contains a group (or family) of elements with the same valence and similar properties.

7. MI #5: Design of the PT (Rows) Periods (or rows) start with an element that is a reactive metal and end with an unreactive gas. Elements in the period are different but their atomic mass increases as you move from left to right.

8. MI #6: Design of the PT (Boxes) Atomic Number Symbol Name Atomic Mass 6 C Carbon 12.0

9. So What…? Real Life Application Understanding the structure of the Periodic Table of the Elements allows us to understand the relationships between elements.