Valence Electrons
When creating our electron configurations in the last lesson we dealt with all of the electrons in an atom. While all of these electrons are important and help define an atom’s characteristics, the outermost electrons are especially important. These electrons are able to interact with other elements to form bonds or they can be lost changing the charge of an atom in addition to much more. Let’s explore these electrons now to get a better sense of why they are so important!
What Are These Electrons?
We call these electrons, valence electrons and they reside in the outermost shell of an atom. Since a shell is represented by its principal quantum number (n) or if we go back to our analogy the floors in our apartment, all of the electrons that share the highest n in an atom are the valence electrons.
For example, chlorine (Cl) has a noble gas electron configuration of Cl:[Ne]3s23p5. Since this configuration only shows the highest energy shells it also shows us the valence electrons of chlorine.
This shell is accessible to the world around it and as a result, it can gain electrons, lose electrons, and form bonds. Ultimately every atom wants to fill up this shell and this property is the basis for bond formation, which we will explore in later lessons.
Furthermore, this property helps us predict periodic table trends, the common ions for different elements, and much more. We will continue to come back to this idea frequently as we go in order to understand why atoms do what they do.
Magnetism
Before moving on I want to take a little bit of time to discuss the link between valence elctrons and the magnetic properties of atoms and elements. In this way, we will get to see valence electrons in action and bring this lesson full circle with our lesson on magnetism.
Electrons Generate Magnetic Fields
As a quick recap, moving charges produce magnetic fields and since electrons are moving charges they too produce magnetic fields. The direction of these fields are wholly determined by an electron’s spin. Whereby an electron spinning clockwise will generate a magnetic field that points upward. While an electron that is spinning counterclockwise will generate a magnetic field that points downward.
When electrons are paired up their magnetic fields cancel making the element non-magnetic. When an electron or multiple electrons are unpaired though the atom will have a net magnetic field. We have fancy names for both types of elements and each will end behaving slightly different in a magnetic field.
Diamagnetic Versus Paramagnetic
The first of these fancy terms is diamagnetic in these elements all of their electrons are paired up resulting in no net magnetic field. As a result these elements are slightly repelled by magnetic fields.
The exact opposite is true of paramagnetic elements. In these elements they have unpaired electrons, net magnetic fields, and are attracted to magnetic fields.
We can better understand this idea by using an analogy where our electrons are dancers. Each dancer want a dance partner and if they don’t already have a partner they will go out and try to find one.
In our diamagnetic elements everyone has a partner so they aren’t going to “play” the field if you will thus they are repelled by magnetic fields. On the other hand, paramagnetic elements have electrons without dance partners so they are going to “play” the field thus they are attracted by magnetic fields.
Memory Aid
It is super easy to mix up these two terms so we can help keep them straight by using a simple memory aid. Think of paramagnetic as un-paramagnetic to remember that these elements have unpaired electrons.
Think of the dia, meaning two, in diamagnetic to represent that each electron is a pair of two electrons. So long as you understand the implications of having paired and unpaired electrons you can work out what magnetic properties each element will end up having.