WE CANNOT KNOW THE EXACT LOCATIONS OF ELECTRONS WITHIN ENERGY LEVELS, BUT WE CAN DESCRIBE PROBABLE REGIONS OF ELECTRON LOCATION.
Our understanding of electron distribution is based on mathematical probabilities that result from knowledge about the behavior of charged particles in an atom: |a) | | |b) | | |c) | |
Consequently, there are three “rules” for predicting the most probable locations of electrons: 1) Electrons always enter the region of lowest energy available. |This concept is called the | |Why does it make sense? |
2) Orbitals never hold more than 2 electrons at a time. |This concept is called the | |Why does it make sense? |
3) Electrons enter separate orbitals in the same sublevel one-at-a time before pairing up. | This concept is called the | |Why does it make sense? |
Try the interactive simulation in your on-line text: Electron Configuration Simulation (needs Shockwave)
The chart below can be used to show the energy levels and sublevels, in order of increasing energy value. You should not memorize it, but look at the patterns it holds. Each energy level is listed (as a “coefficient”), along with the type(s) of sublevels it holds (letters s, p, d, f). The superscripts tell you the maximum number of electrons that can ever be in that sublevel (orbitals combined).
|With this in mind, what does “1s2” mean? | |What does “2p6” mean? | |What is the first principal energy level to have a d sublevel? | |How many electrons can be found in any p sublevel? | |How many energy levels have an s sublevel? |
2s22p6 continue directional arrows as needed
5s25p65d105f14… additional sublevels not used
* Note: the 4s sublevel accepts electrons immediately after the 3p sublevel. The 3d sublevel fills after 4s.
A new principal energy level “opens up” after every p-sublevel is completed. This is consistent with
observed chemical behaviors of elements.
Energy-order takes priority over numeric-order!
Practice: Writing electron configurations. (Hint: to type a superscript, press Ctrl, Shift, and the = keys at the same time. Type your superscript. Press the...