Unit 4: Periodicity

Although three subatomic particles had been discovered by the early 1900s, the quest to understand the atom and its structure had really just begun. That quest continues as scientists pursue an understanding of how electrons are arranged within atoms.

Wouldn’t it be nice if you could easily organize the chemistry knowledge you are acquiring? You can, with the help of the Periodic Table of Elements. It is called the Periodic Table of Elements because, much like the phases of the moon, the properties of the elements in the table repeat in a periodic way.

The Periodic Table will be an invaluable tool as you continue in chemistry. However, before you learn about the modern Periodic Table, a recounting of the history behind the table’s development will help you understand its significance.

Why is this important to us? Why are some fireworks red, some white, and others blue? The key to understanding the chemical behavior of fireworks, and all matter, lies in the understanding how electrons are arranged in atoms of each element. The Periodic Table is the simple most powerful chemistry reference tool available to you. Understanding its organization and interpreting its data will greatly aid you in your study of chemistry. What you know about an element can affect the choices you make. Before all of its properties were known, toxic lead glazes were used to seal clay storage containers. Modern steel cans are lined with tin, which is a non-toxic element similar to lead.

In this unit, you will:

1. Compare the wave and particle models of light.

2. Describe how the frequency of light emitted by an atom is a unique characteristic of that atom.

3. Compare/contrast the Bohr and quantum mechanical models of the atom.

4. Express the arrangement of electrons in atoms through orbital notations, electron configurations, and electron dot structures.

5. Explain why elements in a group have similar properties.

6. Relate the group and period trends seen in the Periodic Table to the electron configurations of the atoms.

7. Identify the s-, p-, d- and, f- blocks of the Periodic Table.

8. Classify elements based on their electron configurations.

9. Relate electron configurations to the properties of the elements.

10. Identify the sources and uses of selected elements.

ª Notes