Energy and Orbit Levels

Today I will be telling you about the electronic structure of the atom.

Energy and Orbital Levels
All atoms have energy. Some, however, are higher than others. Atoms with a high energy state are said to be Hyperkinetic.When one or more electrons have energy levels greater than their lowest energy levels, which is also known as their Ground State,  they will jump to a higher orbital level. "n" represents the energy level.


I'll just tell you what a few words mean:
Excited State: This is when one or more electrons in an atom are in any energy level other than the lowest.
Orbital: This is the region of space that an electron occupies in an energy level.
Shell: This is the set of all orbitals having the same "n" value.
Sub-Shell: This is the set of orbitals of the same type.



There are four types of orbitals, that each contain a different amount of electrons. They are: s,p,d and f.

Here are the different amount of electrons possessed by each orbital of a given "n" value:

Level 1 (n=1): s 
Level 2 (n=2): s and p
Level 3 (n=3): s, p and d
Level 4 (n=4): s, p, s and f 

It is easy to remember how to fill the shells, if you write out this simple diagram to the left and put the diagonals in. There is a bit of a trick to it too which I will tell you about later... But first, let's try an example:

What is the electron configuration of the element Potassium in it's neutral state?
First, you have to figure out how many electrons there are in potassium. (39 - 19 = 20) Therefore, there are nineteen electrons.
Next, all you have to do is fill the orbitals until no electrons are left.

*Note: s can only carry 2 electrons. p can carry 6 electrons. d can carry 10 electrons. And, finally, f can carry 14 electrons.

Electron configuration for potassium:
1s22s22p63s23p64s1

Core notation can be used which is meant to simplify our configurations. Doesn't always work out that way, though...

Example:

What is the core notation for the element Calcium?
Calcium has 20 electrons, and if we write it's configuration, it would be 1s22s22p63s23p64s2.
To simplify it, we have to find the closest noble gas to calcium, without going over, of course. So, that would be Argon, which has 18 electrons. We then take out the first 18 electrons and replace it with [Ar]. Doing this makes the answer [Ar]4s2. This may be simple for an element like calcium, but if we were trying to do Arsenic, well, that is tricky.....

Of course, like everything in life, there are Principles and Rules that must be followed....

The Pauli Exclusion Principle

Wolfgang Pauli. This strapping, young lad to the left came up with a principle that explains how electrons are arranged in an atom. He theorized that, while protons and neutrons remain constant, electrons do not. Pauli said that a certain number of electrons can be put in each specific energy level.This has been proven true. This makes sure that all electrons do not go in the first energy level. He also thought that two electrons would not be able to take up the same  state in a closed system.

The Aufbau Principle
Pauli, with the help of Bohr, also came up with the Aufbau Principle. This principle stated that the lower energy levels should be filled before the higher ones. This is indeed the case.

The Hund's Rule

Friedrich Hund. Another fine, young speciemen that came up with yet another rule. He proposed a law that stated that every electron will pair up, but only  once the previous orbital is full. These electrons will pair up with other electrons with a similar amount of energy.

Now, onto that little trick I promised you earlier...

If you ever are having a hard time remembering the configuration, just look at your Periodic Table:

It is all laid out so beautifully for you! The electronic configuration is in it's proper rows and it has all the right numbers and everything. Makes it all easy as pie, doesn't it?

Now, where would we be without a video to finish us off? Here it is: