What is Aufbau Principle?
Aufbau Principle states that the electrons are filled in subshells in increasing order of energies or n+l values.
Aufbau Rules for Filling Electrons:
- Electrons first occupy Lower energy subshells
2. Filling of Electrons in increasing Order of subshell energy
Aufbau Diagram:
Aufbau diagram describes the increasing order of subshell energies.
Filling of electrons in subshells starts from the tail towards head of the arrow.
Watch Aufbau Principle (spdf trick of Filling Electrons ) in Urdu / Hindi:
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How to write electronic configuration of Elements
Aufbau Rule (spdf Electronic Configuration)
Beryllium (Be) :
Beryllium (Be) has atomic number 4. Be is the fourth element of the periodic table having a total 4 electrons.
Two electrons will fill the lowest energy subshell 1s and the remaining 2 electrons will fill 2s subshell. so the electronic configuration of Beryllium is 1s2 2s2.
Valence shell configuration of Beryllium is 2s2 .
Boron (B) :
Boron(B) has atomic number 5. B is the fifth element of the periodic table having a total 5 electrons.
Two electrons will fill the lowest energy subshell 1s then remaining 2 electrons will fill 2s subshell and 1 electron in 2p subshell. so the electronic configuration of Boron (B) is 1s2 2s2 2p1.
Valence shell configuration of Boron is 2s2 2p1 .
Carbon (C) :
Carbon (C) has atomic number 6. C is the sixth element of the periodic table having a total 6 electrons.
Two electrons will fill the lowest energy subshell 1s then remaining 2 electrons will fill 2s subshell and 2 electrons in 2p subshell. so the electronic configuration of Carbon (C) is 1s2 2s2 2p2.
Valence shell configuration of carbon is 2s2 2p2.
Nitrogen (N) :
Nitrogen(N) has atomic number 7. It is the seventh element of the periodic table having a total 7 electrons.
Two electrons will occupy the lowest energy subshell 1s then remaining 2 electrons will occupy 2s subshell and 3 electrons in 2p subshell. so the electronic configuration of nitrogen (N) is 1s2 2s2 2p3.
Valence shell configuration of N is 2s2 2p3.
Oxygen (O) :
Oxygen(O) has atomic number 8. It is the eighth element of the periodic table having total 8 electrons.
Two electrons will occupy the lowest energy subshell 1s then remaining 2 electrons will occupy 2s subshell and 4 electrons in 2p subshell. so the electronic configuration of oxygen (O) is 1s2 2s2 2p4.
Fluorine (F) :
Fluorine (F) has atomic number 9. It is the ninth element of the periodic table having a total 9 electrons.
Two electrons will occupy the lowest energy subshell 1s then remaining 2 electrons will occupy 2s subshell and 5 electrons in 2p subshell. so the electronic configuration of Fluorine (F) is 1s2 2s2 2p5.
Neon (Ne) :
Neon (Ne) has atomic number 10. It is the tenth element of the periodic table having a total 10 electrons.
Two electrons will occupy the lowest energy subshell 1s then remaining 2 electrons will occupy 2s subshell and 6 electrons in 2p subshell. so the electronic configuration of neon (Ne) is 1s2 2s2 2p6.
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How to write electronic configuration of First 20 Elements of Periodic Table ( in Urdu / Hindi)
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