Why Are Electrons Important?

Brandon, Larry L.                  Thornwood High School
1544 Edgewood Ave.                 339-7800 x 2785
Chicago Heights, IL 60411
756-2635

Objectives:  
The student will be able to write the electron configuration of any 
element, given the atomic number. Given the location of an element on 
the periodic table, the student will be able to give the highest energy 
level the valence electrons are on, and how many valence electrons it 
has. 

Materials:  
1-Hole rubber stopper, #4, 4 or 5 rubber bands, 2 paper clips. 

Strategies:  
Stringing the rubber bands together to make one continuous cord, it is 
run through the hole in the rubber stopper and a paper clip is attached 
to each end (to keep everything together).  This simple apparatus can 
be used to simulate the space-filling property of an electron.  It is 
better than the analogy of a fan, because this model fills a 3-
dimensional space.  Simply moving the hand rapidly in a random motion 
will quickly cause the rubber stopper to soon occupy a spherical 
volume.  It will bang the knuckles from time to time, so it is not 
advisable to use a stopper larger than a #4. 
     Also shown was the diagonal rule for filling orbitals.  This 
     takes the form:

                 1s
                 2s  2p
                 3s  3p  3d
                 4s  4p  4d  4f
                 5s  5p  5d  5f
                 6s  6p  6d  6f
                 7s  7p  7d  7f

Draw diagonal lines from top right to bottom left.  Following the 
lines, when correctly drawn, will give the following order of filling:  
1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 4f, 5d, 6p, 7s, 5f, 6d 
and 7p.  These orbitals will account for all the elements now known.  
This diagonal rule can help account for the octet rule, as well. 

These are two simple activities to help the chemistry teacher discuss 
electrons and their relation to the periodic table.