Concepts and reasonThe concepts used in this problem are electronic configuration, Pauli Exclusion Principle, Aufbau Principle and Hund’s rule. Use the above mentioned rules to find the electronic configuration of phosphorus.
FundamentalsElectronic configuration:Each atom or molecule has some electron(s), the criteria of distributing these electrons in molecular or atomic orbitals is called electronic configuration.Pauli Exclusion Principle:According to this principle, “the location of two electrons cannot be same means the quantum number of two electrons cannot be same. The electrons in the same orbital should have opposite spins.”Aufbau Principle:This principle states that “the orbitals with lowest energy level must be filled first before filling the orbital with higher energy levels.”For example: 2s orbital should be filled before 2p and 1s should be filled before 2s.Hund’s Rule:According to this rule, “each orbital must be first occupied with single electron, then it should be doubly occupied.”For example: If there are 2 electrons for p orbital and p has 3 orbitals, then 2 electrons must be filled in two orbitals, they should not be paired in single orbital.
Step 1
The general order of filling the orbitals is: 1s2,2s2,2p6,3s2,3p6,4s2,3d10,4p6,5s2…………….7f141{s^2},;2{s^2},;2{p^6},;3{s^2},;3{p^6},;4{s^2},;3{d^{10}},;4{p^6},;5{s^2}…………….7{f^{14}}1s2,2s2,2p6,3s2,3p6,4s2,3d10,4p6,5s2................7f14s,p,dandfs,;p,;d;{rm{and}};fs,p,dandf are the orbitals and this is order of filling the orbitals obeying Pauli Exclusion Principle, Aufbau Principle and Hund’s rule.
Explanation: The atomic number of an element is the number of electrons in that element. These electrons are filled in orbitals in the above mentioned order.The maximum number of electrons that can be filled in s orbital are 2 electrons. The maximum number of electrons that can be filled in p orbital are 6 and in d orbital are 10.
Common mistakes: The order of filling the orbitals should not be changed. The orbitals must be filled in standard order i.e. 1s2,2s2,2p6,3s2,3p6,4s2,3d10,4p6,5s2…………….7f141{s^2},;2{s^2},;2{p^6},;3{s^2},;3{p^6},;4{s^2},;3{d^{10}},;4{p^6},;5{s^2}…………….7{f^{14}}1s2,2s2,2p6,3s2,3p6,4s2,3d10,4p6,5s2................7f14
Hint for next step: Fill the electrons in the orbitals in correct order.
Step 2
There are 15 electrons in phosphorus.Two electrons are filled in 1s orbital i.e. 1s2Two electrons are filled in 2s orbital i.e. 2s2Six electrons are filled in 2p orbital i.e. 2p6Two electrons are filled in 3s orbital i.e. 3s2The electrons filled up to 3s2 orbital are: 2+2+6+2=122 + 2 + 6 + 2 = 122+2+6+2=12 So, the number of electrons left are 15−12=315 – 12 = 315−12=3 Three electrons are filled in 3p orbital i.e. 3p3
Explanation: All the electrons have been filled in orbitals obeying all the rules. The 1s orbital is filled before 2s and 2s is filled before 2p and so on.The element is neutral so, the atomic number of phosphorous is equal to the number of electrons and the atomic number is 15.
Common mistakes: The 3s orbital should not be filled before 2p because the energy of 2p orbital is lower than that of 3s. So, 2p should be filled before 3s.
Answer
The electronic configuration is 1s22s22p63s23p3{bf{1}}{{bf{s}}^{bf{2}}};{bf{2}}{{bf{s}}^{bf{2}}};{bf{2}}{{bf{p}}^{bf{6}}};{bf{3}}{{bf{s}}^{bf{2}}};{bf{3}}{{bf{p}}^{bf{3}}}1s22s22p63s23p3 .
Concepts and reasonThe concepts used in this problem are electronic configuration, Pauli Exclusion Principle, Aufbau Principle and Hund’s rule. Use the above mentioned rules to find the electronic configuration of phosphorus.
FundamentalsElectronic configuration:Each atom or molecule has some electron(s), the criteria of distributing these electrons in molecular or atomic orbitals is called electronic configuration.Pauli Exclusion Principle:According to this principle, “the location of two electrons cannot be same means the quantum number of two electrons cannot be same. The electrons in the same orbital should have opposite spins.”Aufbau Principle:This principle states that “the orbitals with lowest energy level must be filled first before filling the orbital with higher energy levels.”For example: 2s orbital should be filled before 2p and 1s should be filled before 2s.Hund’s Rule:According to this rule, “each orbital must be first occupied with single electron, then it should be doubly occupied.”For example: If there are 2 electrons for p orbital and p has 3 orbitals, then 2 electrons must be filled in two orbitals, they should not be paired in single orbital.
Step 1
The general order of filling the orbitals is: 1s2,2s2,2p6,3s2,3p6,4s2,3d10,4p6,5s2…………….7f141{s^2},;2{s^2},;2{p^6},;3{s^2},;3{p^6},;4{s^2},;3{d^{10}},;4{p^6},;5{s^2}…………….7{f^{14}}1s2,2s2,2p6,3s2,3p6,4s2,3d10,4p6,5s2................7f14 s,p,dandfs,;p,;d;{rm{and}};fs,p,dandf are the orbitals and this is order of filling the orbitals obeying Pauli Exclusion Principle, Aufbau Principle and Hund’s rule.
Explanation: The atomic number of an element is the number of electrons in that element. These electrons are filled in orbitals in the above mentioned order.The maximum number of electrons that can be filled in s orbital are 2 electrons. The maximum number of electrons that can be filled in p orbital are 6 and in d orbital are 10.
Common mistakes: The order of filling the orbitals should not be changed. The orbitals must be filled in standard order i.e. 1s2,2s2,2p6,3s2,3p6,4s2,3d10,4p6,5s2…………….7f141{s^2},;2{s^2},;2{p^6},;3{s^2},;3{p^6},;4{s^2},;3{d^{10}},;4{p^6},;5{s^2}…………….7{f^{14}}1s2,2s2,2p6,3s2,3p6,4s2,3d10,4p6,5s2................7f14
Hint for next step: Fill the electrons in the orbitals in correct order.
Step 2
There are 15 electrons in phosphorus.Two electrons are filled in 1s orbital i.e. 1s2Two electrons are filled in 2s orbital i.e. 2s2Six electrons are filled in 2p orbital i.e. 2p6Two electrons are filled in 3s orbital i.e. 3s2The electrons filled up to 3s2 orbital are: 2+2+6+2=122 + 2 + 6 + 2 = 122+2+6+2=12 So, the number of electrons left are 15−12=315 – 12 = 315−12=3 Three electrons are filled in 3p orbital i.e. 3p3
Explanation: All the electrons have been filled in orbitals obeying all the rules. The 1s orbital is filled before 2s and 2s is filled before 2p and so on.The element is neutral so, the atomic number of phosphorous is equal to the number of electrons and the atomic number is 15.
Common mistakes: The 3s orbital should not be filled before 2p because the energy of 2p orbital is lower than that of 3s. So, 2p should be filled before 3s.
Answer
The electronic configuration is 1s22s22p63s23p3{bf{1}}{{bf{s}}^{bf{2}}};{bf{2}}{{bf{s}}^{bf{2}}};{bf{2}}{{bf{p}}^{bf{6}}};{bf{3}}{{bf{s}}^{bf{2}}};{bf{3}}{{bf{p}}^{bf{3}}}1s22s22p63s23p3 .