Quantum theory of the atom - parts 1 & 2

We are all familiar with the electron shell configuration of 2, 8, 18, 32, 32, 18, 8. The quantum theory is a much greater elaboration on this but respect to Bohr (original model founder) is paid duly.
Electrons behave like waves, yes waves and have a specific wavelength - like photons but not, as you'll see.
Electrons can be found around the nucleus in orbitals and these orbitals have orbital types anf they are S, P, D and F. The respective orbital is reference to position and shape of orbital as each one has a specific shape - S is spherical, P is dumb-bell shaped, D has 4 cloves (like leaves) and F has 8 cloves (very complex).
Another term that suits these orbitals is clouds.

Now, how Bohr is respected is his layout (above) is abided by otherwise the periodic tables' laws would be either redone or completely irrelevant. What is different is how we come to the conclusion that they are abided by.

It's important to start with the point that an orbital can only hold 2 electrons and 2 electrons only - so therefore if we only have four orbitals that means only 8 electrons in total, which is impossible as we have over 100 elements in the periodic table.

You may guess, that it is going to get slightly tricky now however, once explained, it makes sense, perfect sense.

To be continued........

2nd part!

3 rules are strictly abided by and they are:

1. The Heisenberg Uncertainty Principle - if we know the position of an Electron then we can have no idea how fast it is travelling and in which direction.

2. The Pauli Exclusion Principle - no 2 Electrons can occupy the same space at the same time - ever.

3. Hund's rule - all the lowest energy levels (those closest to the nucleus) must be filled first, if you can imagine a bus/train that has 40 seats (20 x 2) then it would be typical for the first twenty people to get on the bus/train and sit by themselves - spacing themselves out, Electrons behave in the same way.

Back to the orbitals.......

In order of lowest level first -

1S
2S 2P
3S 3P 3D
4S 4P 4D 4F
5S 5P 5D 5F
6S 6P 6D
7S 7P

Now, if you are thinking back to the " 2 Electrons to an orbital" you will see its impossible, unless the orbitals are different, which they are.

• All S orbitals hold 2 electrons max
• All P orbitals hold 6 electrons max - remember the cloves
• All D orbitals can hold 10 electrons max
• All F orbitals can hold 14 electrons max

So the in-depth configuration - at a maximium - looks like this.

1S (2)
2S (2) 2P (6)
3S (2) 3P (6) 3D (10)
4S (2) 4P (6) 4D (10) 4F (14)
5S (2) 5P (6) 5D (10) 5F (14)
6S (2) 6P (6) 6D (10)
7S (2) 7P (6)


 Now if you look closely, you can see Bohrs model within by totalling the electrons of each line:

2
8
18
32
32
18
8

Its important to try and visualise the atom from above with all these potential orbitals surrounding it.





This picture may help!


Here are the maximum orbitals - the arrows are a reference to Hunds rule - the lowest available energy level will be filled first:







You can see that there are potentially 7 S orbitals that can be filled, this is a key difference compared to Bohrs' model - Bohrs model is very "Solar System" like - Nucleus=Sun, Orbitals=Planets. The Quantum model is more complex as rather than Bohrs' 7 orbitals, it has 19 orbitals!

Again, Bohr wasn't a mile off being correct by any means and Scientists are often corrected (sorry for the word choice) by more contemporary theories because of the available technologies. However, if it wasn't for Bohr we may not have the understanding that we do now. Science is all about progress as that is what it is, constant work stacked up over time to understand how our Universe, and all within it, works.

To be continued.........