http://www.ck12.org Chapter 6. The Periodic Table
6.2 Electron Configuration and the Periodic Table
Lesson Objectives
- Understand the relationship between the number of orbitals in various energy sublevels and the length of the
periods in the periodic table. - Identify each block of the periodic table and be able to determine which block each element belongs to based
on its electron configuration. - Describe the relationship between outer electron configuration and group number. Be able to determine the
number of valence electrons for any element. - Locate the following groups on the periodic table: alkali metals, alkaline earth metals, halogens, and noble
gases. - Locate the transition elements, lanthanides, and actinides on the periodic table.
Lesson Vocabulary
- actinide
- alkali metal
- alkaline earth metal
- halogen
- inner transition element
- lanthanide
- noble gas
- representative (main-group) elements
- transition element
The development of the periodic table was largely based on elements that display similar chemical behavior. In the
modern table, these elements are found in vertical columns called groups. In this lesson, you will see how the form
of the periodic table is related to electron configurations, which in turn influences chemical reactivity.
Periods and Blocks
There are seven horizontal rows, or periods, on the periodic table. The length of each period is determined by
electron capacity of the sublevels that fill during that period, as seen below (Table6.2).
TABLE6.2: Period Length and Sublevels in the Periodic Table
Period Number of Elements in Period Sublevels in Order of Filling
1 2 1 s
2 8 2 s 2 p