Exploring Pauli Exclusion Principle: SP3 Orbitals & Electron Spin

In summary: By splitting the original level of energy into two different levels, the energy of the system is lowered overall.
  • #1
RaduAndrei
114
1
The 3s and 3p orbitals are filled by 4 electrons.A single atom has [Ne]3s2 3p2.But when multiple atoms get together they do so in order to minimize the overall energy.And to minimize the overall energy,the 3s and 3p orbitals hybridize to form 4 tetrahedral SP3 orbitals.And the Si atoms get together by joining their 4 SP3 orbitals.Each SP3 orbital has one electron and is capable of forming a bond with a neighboring atom.So each atom has 4 neighboring atoms.

Am I right?

And when two SP3 orbitals of two atoms join together to form a molecular orbital they do so in order to respect Pauli exclusion principle(the 2 electrons from the 2 SP3 orbitals cannot occupy the same quantum state simultaneously).That is the originial SP3 energy level in 2 energy levels:bonding state and anti-bonding state.And the electrons now occupy the bonding state...one electrons has a spin up and the other a spin down.

So here is my question.Why can't the 2 electrons have different spins in the same molecular orbital,the same original SP3 level?Why must nature split this original level in 2 different energy levels?
 
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  • #2
Of course electrons can fill the same atomic orbital with different spins. They do so in so called lone pairs, e.g. in NH3 where there are thre bonds between N and H and one lone pair at N.

A bond is formed because the electrons can then move in the potential trough of two nuclei thus lowering their kinetic energy.
Pauli principle is merely a complication.
 
  • #3
This is basically the same has Hund's rule. You first fill up all available orbitals with one spin direction, and only when all orbitals are occupied by one electron you add the second electron with opposite spin.

http://en.wikipedia.org/wiki/Hund's_rule
http://en.wikipedia.org/wiki/List_of_Hund's_rules

The reason for this is that electrons different orbitals are less efficiently screened from the nuclear charge and thus have lower energy.
 

Related to Exploring Pauli Exclusion Principle: SP3 Orbitals & Electron Spin

1. What is Pauli Exclusion Principle?

Pauli Exclusion Principle is a fundamental principle in quantum mechanics that states that no two electrons in an atom can have the same set of quantum numbers. This means that in a given orbital, only two electrons can exist and they must have opposite spin.

2. What are SP3 orbitals?

SP3 orbitals are hybrid orbitals that result from the combination of one 2s orbital and three 2p orbitals. These orbitals are used to describe the electronic structure of molecules with four electron groups around the central atom, such as methane (CH4).

3. What is electron spin?

Electron spin is a property of electrons that describes the intrinsic angular momentum of the electron. It is denoted by the quantum number ms and can have two values: +1/2 (spin up) or -1/2 (spin down).

4. How does the Pauli Exclusion Principle apply to SP3 orbitals?

The Pauli Exclusion Principle applies to SP3 orbitals by limiting the number of electrons that can occupy each orbital. Each SP3 orbital can hold a maximum of 2 electrons with opposite spin, following the principle that no two electrons can have the same set of quantum numbers.

5. Why is the Pauli Exclusion Principle important in understanding atomic and molecular structures?

The Pauli Exclusion Principle is important because it explains the stability of atoms and molecules by preventing electrons from occupying the same energy level and space. It also plays a crucial role in determining the electronic configuration and chemical properties of elements and compounds.

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