Electrons in Atoms: Introductory Comments

This unit is about where the electrons are located in an atom and some aspects of how they behave. In a high school class, what is usually given are the answers and only a tiny bit of why the answers are the way they are.

For example, you will soon learn the the ground state electron configuration for sodium is 1s2 2s22p6 3s1. Once you learn the pattern, such answers will come easy. However, the process by which the above answer was discovered was decades-long and involved many, many people and lots of blind alleys and wrong turns. You simply won't have the time to learn much about this process.

However, you will learn a little of it. That is why units like this one typically start out with a discussion of light and what a spectrum is. The reason for this is that the above configuration (and many others) was discovered through intensive study of the spectra of the elements, principally hydrogen's spectrum.

All these discoveries about how electrons in an atom behave must be able to account for the behavior of the elements. Why are some elements very chemically reactive? Why are some not so reactive? Why does one member of a otherwise similar-behaving group of elements engage in different behavior from the others? Why, where certain chemical react, is one substance produced, but not another? Why cannot certain chemical compounds be made? The list goes on and on and on, as you can well imagine.

I have no wise words that will help make this unit easy. It is not, because the ideas involved are very complex. All I can say is, if you are stuck, do not give up. Take a break, eat some ice cream and go back and try it again. You'll do just fine.