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Pauli exclusion principle

Basic Knowledge

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Pauli exclusion principle

  1. 1. PAULI EXCLUSION PRINCIPLE 1-Pauli Exclusion Principle 2-Uses of the principle in periodic table May 2019
  2. 2. Presented to:- Prof. Dr. M. Irfan Presented by:-  Muhammad Imran  Muhammad Sohail  Muhammad Salahuddin  Muhammad Shakeel  Tanveer Azmat 2
  3. 3. Concept of Shells & Subshells These are actually the residing places of electrons in an atom.  Shells are energy levels around the nucleus of an atom. These are subdivided into sub-energy levels called subshells  Shells and Subshells are called orbits and orbitals respectively.  Shells are designated with numbers as n=1,2,3,… and named as K,L,M… in correspondence. 3
  4. 4. Intro to Orbitals Also Known as Subshells or sub energy levels.  They are named as s, p, d, f and so on with numeric values as 0,1,2,3…..  Every Orbit has fixed number of orbitals  Every orbital has fixed capacity to place electrons  For Example s has 2, p =6, d=10 and f=14.  These orbitals have subdivisions to occupy electrons and each subdivision can have only two electrons in it. 4
  5. 5. PAULI EXCLUSION PRINCIPLE Based upon the previous electronic management in an atom we’ll try to explain the above mentioned principle Principle states that:-  Orbital can hold maximum of two electrons  If two electron in an orbital, must have opposite spin  Two possible spins are clockwise and anticlockwise or simply up and down 5
  6. 6. Quantum Numbers There are four quantum numbers which help in the explanation of atomic structure and construction of periodic table. Those are:-  Principle Quantum Number (n) where n= 1, 2, 3,…..  Azimuthal Quantum Number(l) where l= 0, 1, 2,…….  Spin Quantum Number(s) where s= +(1/2) & -(1/2)  Magnetic Quantum Number(m) where m= 0,±1,±2,………. 6
  7. 7. Construction Of Periodic Table & Pauli Exclusion Principle The construction of the existing periodic table would not have been possible without “the Pauli Exclusion Principle”. But we also need to utilize and follow following rules:-  Hund’s Rule  Aufbao Principle The above mentioned two rules along with the exclusion principle help in construction of periodic table. 7
  8. 8. 8 Main points for construction of Periodic Table  Filling of Electrons in Shells/Subshells/sublevels( “/” shows path)  Energy wise Sequence of Electronic Configuration  Placement of elements in respective Blocks
  9. 9. 9 Filling of Electrons in Shells/Subshells/sublevels Considering Shell 2 or L with n=2, l=0,1 m=0,±1
  10. 10. 10 Energy wise Sequence of Electronic Configuration • Electronic Configuration refers to the distribution of electrons in shells and subshells according to their increasing energy levels or simply depending upon the energy of sublevels
  11. 11. 11 Here is the trick for energy wise sequence
  12. 12. 12 Placement of elements in respective Blocks The periodic table is styled with a block distribution of the elements depending upon their chemical properties which is directly governed by electronic configuration of the shells, ultimately Pauli Exclusion Principle stood responsible for the chemical properties of elements and development Periodic table. Following Picture shows the blocks along with configuration:-
  13. 13. 13 Blocks in Periodic Table
  14. 14. 14 Importance Of Pauli Exclusion Principle If this principle were not valid, an atom could radiate energy until every electron in the atom is in the lowest possible energy state and therefore the chemical behavior of the elements would be grossly modified. Nature as we know it would not exist. That’s the importance of Pauli Exclusion Principle in the construction of periodic table.
  15. 15. THANK YOU! Group-C Email imran8163733@gmail.com