1. CHAPTER 6 THE PERIODIC TABLE

2. HISTORY 1789 - Antoine Lavoisier 1869 - Dmitri Mendeleev Increasing mass Properties Made predictions about missing elements

3. HISTORY Henry Mosley Used the atomic number to alter Mendeleev’s table – properties fit better as a result Periodic Law - Pattern of Repeating Properties

4. Elements in a group or “family” have similar properties. Periods = Energy Levels

5. Largest class of elements on the Periodic Table - Metals. 80% of the elements. PERIODIC TABLE: ELEMENT CLASSIFICATIONS

6. Groups/Families

7. 1A 2A 3B 4B 8A 6A 7A 4A 5A 3A 6B 7B --8B--1B2B 5B Rare-Earth metals or Inner transition:

8. Modern periodic table – stretched out (7 rows) Shows periods with Lanthanide & Actinide series or inner transition metals where they really belong THE PERIODIC LAW

9. VALENCE ELECTRONS Why do the elements in a group have similar properties?

10. They have the same number of valence electrons. The properties are not identical because the valence electrons are in different energy levels. A valence electron is an electron that is (generally) in the highest occupied energy level of an atom. Valence electrons play a key role in chemical reactions. VALENCE ELECTRONS Why do the elements in a group have similar properties?

11. VALENCE ELECTRONS How do we determine the number of valence electrons?

12. PERIODIC TRENDS Atomic Radius Ionic Radius Ion – Charged atom or group of atoms – result of gaining or losing electrons to fulfill the Octet Rule Cation – Postive Ion – Loses electrons (metals) Anions – Negative Ion – Gains Electrons (nonmetals) Ionization Energy Electronegativity

13. ATOMIC RADIUS

14. TRENDS PG 178 Atomic Mass Increases Atomic Radius Decreases Ionization Energy Increases Electronegativity Increases Atomic Mass Increases Atomic Radius Increases Ionization Energy Decreases Electronegativity Decreases