5.1 Organizing the Elements
Reading Focus
Key Concepts
How did Mendeleev organize the elements in his periodic table?- What evidence helped verify the usefulness of Mendeleev's table?
Vocabulary
periodic table
Reading Strategy
Identifying Main Ideas
Copy the table. As you read, write the main idea for each topic.
Topic |
Main Idea |
|---|---|
Mendeleev's proposal |
a. |
Mendeleev's prediction |
b. |
Evidence supporting Mendeleev's table |
c. |
In a department store, clothes for men, women, and children are in different departments. Within some departments, items are furthergrouped by size or cost. The store manager has to choose a set of categories and then place each item in the most appropriate location.
Scientists faced a similar challenge when they looked for a logical way to organize the elements. They had to decide what categories to use and where to place each element. An organized table of the elements is one of the most useful tools in chemistry. The placement of elements on the table reveals the link between the atomic structure of elements and their properties.
Figure 1 This directory shows how items are organized by floor in one department store.
The Search for Order
Until 1750, scientists had identified only 17 elements. These elements were mainly metals, such as copper and iron. The rate of discovery increased rapidly as chemists began to investigate materials in a systematic way. As the number of known elements grew, so did the need to organize them into groups based on their properties.
In 1789, French chemist Antoine Lavoisier (la vwah zee ay) grouped the known elements into categories he called metals, nonmetals, gases, and earths. For the next 80 years, scientists looked for different ways to classify the elements. But none of their systems provided an organizing principle that worked for all the known elements. A Russian chemist and teacher, Dmitri Mendeleev (Duh mee tree Men duh lay uff), would discover such a principle.
Table of Contents