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Name: neni
Status: student
Grade: 6-8
Location: FL
Country: N/A
Date: 1/24/2006


Question:
Please explain what electrons have to do with chemical reactions.


Replies:



Replies:
Neni,

Thanks for your question.

If you look at a Periodic Table of the Elements, you will learn that elements in the same column have similar chemical properties. For example, all of the elements in the first column (excluding hydrogen) are very highly reactive metals.

The reason elements in the same column have similar chemical properties is because they have the same number of outer shell ("valence") electrons. For example, all the highly reactive metals in the first column of the periodic table have one valence electron; the elements in column two have two valence electrons. The noble gases (in the column on the far right) have 8 valence electrons (except for Helium, which has 2) and 8 (or 2) is the maximum number -- so those elements tend to not react easily with other chemicals.

One of the best things that you can help your middle school students understand is that it is the electrons -- specifically the outer shell, valence electrons, that determine how an element will react chemically. Many students get stuck on the number of protons determining whether an atom is gold, or oxygen, or tin. And although that is true, it really the number and arrangement of the electrons that determine how an element will react chemically.

Here are some websites with more information:

http://www.visionlearning.com/library/module_viewer.php?mid=54&l=&c3=

http://www.colorado.edu/physics/2000/periodic_table/atomic_structure2.html

Regards,

Todd Clark, Office of Science
US Department of Energy



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