All students of science know that every thing on this earth is made of different types of atoms. But each stom contain number of electrons.Accorging to Ethen siegal “Each electron, in addition to the quantum properties inherent to themselves (like mass, charge, etc.) also have quantum properties that are specific to the bound state they’re in. When they’re bound to an atomic nucleus, that includes energy level, angular momentum, magnetic quantum number, and spin quantum number.”
The lowest-energy electron in an atom will occupy the lowest (n = 1) energy level, and will have no angular momentum (l = 0) and therefore a magnetic quantum number of 0 as well. The electron’s spin, though, offers a second possibility. Every electron has a spin of ½, and so will the electron in the lowest-energy (1s) state in an atom.
When one add a second electron, it can have the same spin but be oriented in the opposite direction, for an effective spin of -½. This way, one can accomodsy two electrons into the 1s orbital
The Pauli Exclusion Principle — and the fact that we have the quantum numbers given by Bohrs model of atom,— is what gives each individual atom their own unique structure.
As one add greater numbers of electrons to ones atoms, one has to go to higher energy levels,there will be greater angular momenta, and increasingly more complex orbitals to find homes for all of them.
The energy levels work as follows:
The lowest (n = 1) energy level has an s-orbital only, as it has no angular momentum (l = 0) and can hold just two (spin +½ and -½) electrons.
The second (n = 2) energy level has s-orbitals and p-orbitals, as it can have an angular momentum of 0 (l = 0) or 1 (l = 1), which means you can have the 2s orbital (where you have spin +½ and -½ electrons) holding two electrons and the 2p orbital (with magnetic numbers -1, 0, and +1, each of which holds spin +½ and -½ electrons) holding six electrons.
The third (n = 3) energy level has s, p, and d-orbitals, where the d-orbital has an angular momentum of 2 (l = 2), and therefore can have five possibilities for magnetic numbers (-2, -1, 0, +1, +2), and can therefore hold a total of ten electrons, in addition to the 3s (which holds two electrons) and 3p (which holds six electrons) orbitals.
Each individual atom on the periodic table, under this vital quantum rule, will have a different electron configuration than every other element.
According to Siegal “No two elements, no matter how similar, will be the same in terms of the structures they form. This is the root of why we have so many possibilities for how many different types of molecules and complex structures that we can form with just a few simple raw ingredients. Each new electron that we add has to have different quantum numbers than all the electrons before it, which alters how that atom will interact with everything element. “
Hence for each individual atom of when combining with any other atom to form a chemical or biological compound there are many possibilities. There is limit less possible combinations that atoms can come together in;
It is also true while certain configurations are certainly more energetically favorable than others, a variety of energy conditions exist in nature, forming the way to form compounds that even the cleverest of humans would have difficulty imagining.
Question is what is the reason that atoms behave this way, and that there are so many wonderful compounds are formed by combining them.The answer is that one cannot put an arbitrary number of electrons into the same quantum state. Electrons are fermions, and we mostly underappreciat Paulis quantum rule ,but it is the one who prevents any two identical fermions from having the same exact quantum numbers.
According to Siegal”If we didn’t have the Pauli Exclusion Principle to prevent multiple fermions from having the same quantum state, our Universe would be extremely different. Every atom would have almost identical properties to hydrogen, making the possible structures we could form extremely simplistic. White dwarf stars and neutron stars, held up in our Universe by the degeneracy pressure provided by the Pauli Exclusion Principle, would collapse into black holes. And, most horrifically, carbon-based organic compounds — the building blocks of all life as we know it — would be an impossibility for us.”
The Pauli Exclusion Principle isn’t the first thing we think of when we think of the quantum rules that govern reality, but it should be given first thought.
Friends without quantum uncertainty or wave-particle duality, our Universe would be different, but life could still exist.
Moral of story is Pauli exclusion principle is bold principle which has given diversity in species of this Earth.
Sukarma Thareja
Alumnus IITK
India
