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Electrons and Sublevels  Electron Configurations and the Periodic Table  Writing Electron Configurations  Box and Arrow Configurations using Pauli Exclusion Principle and Hund's Rule   Quantum Numbers

 

Box and Arrow Orbital Configurations using

Pauli Exclusion Principle and Hund's Rule

 

There is yet another way to writing electron configurations.  It is called the "Box and Arrow" (or circle and X) orbital configuration.

Sublevels can be broken down into regions called "orbitals".  An orbital is defined as the most probable location for finding an electron.  Each orbital holds 2 electrons.

sublevel # of electrons in each sublevel # of orbitals Names of each orbital
s 2 1 s
p 6 3 pz  ppy
d 10 5 dz2  dxz  dyz  dxy  dx2-y2
f 14 7 fzfxzfyzfxyz  fz(x2-y2fx(x2-3y2fy(3x2-y2)
g 18 9  

 

This sublevel configuration can be broken down into orbitals (boxes).

1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6........

There are a few rules for the box and arrow configurations.

 Aufbau Principle - electrons fill orbitals starting at the lowest available energy state before filling higher states  (1s before 2s).

Pauli Exclusion Principle

An orbital can hold 0, 1, or 2 electrons only, and if there are two electrons in the orbital, they must have opposite (paired) spins.

When we draw electrons, we use up and down arrows. So, if an electron is paired up in a box, one arrow is up and the second must be down.

(Therefore, no two electrons in the same atom can have the same set of four Quantum Numbers. )

 

Hund’s Rule

When filling sublevels other than s, electrons are placed in individual orbitals before they are paired up.

Electrons fill like people do on a bus. You would never sit right next to someone you did not know if there are free seats available, unless of course all the seats are taken then you must pair up.

So when working with the p sublevel, electrons fill like this....up, up, up...down, down, down...take a look

atom orbital box diagram
B
1s

2s

2p
C
1s

2s

2p
N
1s

2s

2p
O
1s

2s

2p
F
1s

2s

2p
Cl
1s

2s

2p

3s

3p
   
Mn
1s

2s

2p

3s

3p

4s

3d

 on to Quantum Numbers

Electrons and Sublevels  Electron Configurations and the Periodic Table  Writing Electron Configurations  Box and Arrow Configurations using Pauli Exclusion Principle and Hund's Rule   Quantum Numbers

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