Table of Contents The Periodic Table Section 1 How Are Elements Organized? Section 2 Tour of the Periodic Table Section 3 Trends in the Periodic Table Chapter 4

Objectives Describe the historical development of the periodic table. Describe the organization of modern periodic table according to the periodic law. Section 1 How Are Elements Organized? Chapter 4

Dmitri Mendeleev (1860s): -arranged elements by increasing atomic number. -Predicted properties of missing elements. Example: Te and I Why was it that a few elements didn’t seem to fall into the right place if arranged by atomic mass?

Patterns in Element Properties Predicted Versus Actual Properties for Three Elements Section 1 How Are Elements Organized? Chapter 4 GROUP activity of two

Henry Moseley (40 years later) -discovered that each element has a unique atomic number -arranged elements by increasing atomic number -now all elements fit into place based on properties

Modern Periodic Law: Properties of elements repeat when elements are arranged by increasing atomic number. Questions about the extended periodic table: What is the similar characteristic in each column? What happens to the number of the energy level as you begin each new row? Section 1 How Are Elements Organized? Chapter 4

Section 1 How Are Elements Organized? Chapter 4 s-sec p- sec d-sec d 5 4d 6 4f 5f 5d 7 6d What happens to the number of the energy level as you begin each new row? Find e.config. of each column

Blocks of the Periodic Table Section 1 How Are Elements Organized? Chapter 4

The Periodic Law Elements in the same column: have similar electron configuration. have same number of ______________ electron (the same number of electrons in their outer energy level). have similar ______________ properties. Elements with the same number of valence electrons tend to react in similar ways. Section 1 How Are Elements Organized? Chapter 4

The Periodic Law Noble gases have full outer ___________ level. have ______ valence electron. are stable. Section 1 How Are Elements Organized? Chapter 4

Organization of the Periodic Table Period: A horizontal row on the periodic table Tells energy levels. Group or Falimies: A vertical column on the periodic table is called a group. Elements in a group share chemical properties. Section 1 How Are Elements Organized? Chapter 4

Organization of the Periodic Table Group or Families: There are 18 families or groups. A vertical column on the Period Table. For columns 1-2 and the number in the one’s place (last digit) represents the number of valence electrons. Elements in a group the same chemical properties. Section 1 How Are Elements Organized? Chapter 4

The Periodic Law, continued Organization of the Periodic Table, continued The periodic table provides information about each element. atomic number symbol name average atomic mass electron configuration Section 1 How Are Elements Organized? Chapter 4