First of all the PEP serves the function of allowing objects composed of matter to remain separate. Without it we most likely would not be having this experience of using Physics Stack Exchange to great benefit. Secondly as was touched upon in the question for two bound electrons in an atom to occupy the first shell one of them must adopt the opposite spin to the other.
If the atom has three bound electrons one must jump to the second shell since there are only two spin states. As electrons fill out shells matter acquires stability and volume. A neutron star shows us the extreme case of the PEP allowing matter an incredible resistance against gravitational forces.
As far as I know the PEP is not even violated in this example and it is the Heisenberg Uncertainty Principle which allows momentum space to expand as position space radius decreases until time-dilation becomes infinite at the surface.
Sign up to join this community. The best answers are voted up and rise to the top. Stack Overflow for Teams — Collaborate and share knowledge with a private group. Create a free Team What is Teams? Learn more. Is there is a reason for Pauli's Exclusion Principle? Ask Question. Asked 7 years, 10 months ago. Active 1 year, 9 months ago. Viewed 2k times. Improve this question. Cheshire Cat Cheshire Cat 4 4 silver badges 16 16 bronze badges. Add a comment. Active Oldest Votes.
This ultimate equality of quantum particles leads to all-important consequences governing the structure and dynamics of atoms and molecules, neutron stars, black-body radiation and determining our life in all its intricacy. For instance, molecular oxygen in air is extremely reactive, so why do our lungs not just burn? The reason lies in the pairing of electron spins: ordinary oxygen molecules are paramagnetic with unpaired electrons that have parallel spins, and in respiration this means that electrons have to be transferred one after the other.
This sequential character to electron transfers is due to the EP, and moderates the rate of oxygen attachment to haemoglobin. Think of that the next time you breathe! IOP Publishing Jobs. Sign in Register. Enter e-mail address Show Enter password Remember me. Enter e-mail address This e-mail address will be used to create your account. Reset your password. Please enter the e-mail address you used to register to reset your password Enter e-mail address.
Registration complete. Share this article on Facebook Share this article on Twitter Share this article via email Print this article. Theory Feature Putting the Pauli exclusion principle on trial 16 February W Pauli Phys. A B Govorkov Phys. O W Greenberg Phys. D 43 C 22 E Ramberg and G Snow Phys.
B VIP2 Collaboration Entropy 19 A Dolgov and A Smirnov Phys. B 1. D English et al. An example is the neutral helium atom, which has two bound electrons, both of which can occupy the lowest-energy 1s states by acquiring opposite spin. As spin is part of the quantum state of the electron, the two electrons are in different quantum states and do not violate the Pauli exclusion principle. However, there are only two distinct spin values for a given energy state.
This property thus mandates that a lithium atom, which has three bound electrons, cannot have its third electron reside in the 1s state; it must occupy one of the higher-energy 2s states instead. Similarly, successively larger elements must have shells of successively higher energy. Because the chemical properties of an element largely depend on the number of electrons in the outermost shell, atoms with different numbers of shells but the same number of electrons in the outermost shell still behave similarly.
For this reason, elements are defined by their groups and not their periods. Boundless vets and curates high-quality, openly licensed content from around the Internet.
This particular resource used the following sources:. Skip to main content. Introduction to Quantum Theory.
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