http://www.ck12.org Chapter 2. Matter
2.45 Mendeleev’s Periodic Table
- State how Mendeleev developed his periodic table of the elements.
- Identify the groups and periods of Mendeleev’s table.
- Explain why Mendeleev’s table was a good model.
Look at the left-hand photo above. What a messy closet! Do you have a messy closet too? If you do, then you know
how hard it can be to find a specific item of clothing. If you don’t have a messy closet, just imagine trying to find a
particular shirt or pair of jeans in the closet above. It could take a long time, and it would probably make you late
for school! Now look at the closet on the right. It’s very neat and well organized. With a closet like this, it would be
easy to find whatever item you wanted.
Q:What do these two closets have to do with science?
A:They show why it’s important to keep things organized, including the elements, which are the pure substances
that make up all kinds of matter.
Organizing Elements
For many years, scientists looked for a good way to organize the elements. This became increasingly important as
more and more elements were discovered. An ingenious method of organizing elements was developed in 1869 by a
Russian scientist named Dmitri Mendeleev, who is pictured 2.89. Mendeleev’s method of organizing elements was
later revised, but it served as a basis for the method that is still used today. You can learn more about Mendeleev
and his work at this URL: http://videos.howstuffworks.com/science-channel/27862-100-greatest-discoveries-the-p
eriodic-table-video.htm.
Mendeleev was a teacher as well as a chemist. He was writing a chemistry textbook and wanted to find a way to
organize the 63 known elements so it would be easier for students to learn about them. He made a set of cards of