

Electronic Configuration and Octet
To understand the electronic configuration in Group 15 elements, we have to first understand the basic fundamental principles by which the electrons in an atom are arranged. The theoretical method by which electrons of an element are arranged in their subshells and orbital shells is referred to as electronic configuration. The structure of an atom is such that it consists of a nucleus which is surrounded by electrons that move in an orbital path around the particle. So, when there is an interaction of an atom with another particle, then the electrons on the outer side are the first ones that make contact.
It is important to note that if the outermost shell of an atom does not have the complete set of electrons, then that atom is considered to be reactive. As the reactivity is based on the number of electrons in the outer shell, the chemical properties of an element are also influenced by the electrons in its outer shell. These properties are found to be similar for the elements which have the same number of electrons in their outer shell.
We also use the electronic configurations of an element to tell whether it is found in nature in a stable form or not. The stability of the atoms depends upon the energy levels and number of atoms in their orbital path corresponding to the number of electrons required to complete its octet. So, those atoms which have a complete octet in their outermost shell are considered to be stable. The noble gases are a good example to show which elements are considered stable. We can also predict the reactivity of an element by using the octet rule. To study the electronic configuration of group 15 elements, such as the electronic configuration of nitrogen, the key is to remember the three basic laws, which are Paulie’s Exclusion Principle, Hund’s Law, and Aufbau’s Principle.
Pauli’s Exclusion Principle
Wolfgang Pauli came up with Pauli’s exclusion principle for electrons in 1925. Now to understand the concept clearly, you must know these terms:
Quantum number = n
Azimuthal quantum number = m
Principle quantum number= l
The methodology to fill electrons in an atom is from lower energy levels to higher energy levels. According to Pauli’s exclusion principle, the electrons of an atom should not possess the same n, m, and l simultaneously. For instance, the n,m, and l for an electron in the same orbital path are the same. Then their magnetic quantum number would be the same as well, and hence they would possess opposite integer spins, i.e. ½ and -½. Pauli's exclusion principle does not hold for bosons (particles with integer spin). Since several bosons are capable of holding the same quantum state. Also, this principle helps get a clear picture of orbital shells of an atom.
Hund’s Rule
According to Hund's rule, when filling orbitals with energy levels, an electron looks to fill subshells with the same energy levels before pairing them with other electrons. In other words, all the orbitals must be filled with single electrons first. By filling all the orbitals with individual particles having the same energy levels allows maximizing the total spin. This process is due to all single filled electrons having the same integer spin.
Aufbau’s Principle
Aufbau's principle states that while filling the orbitals with electrons in an atom, it should always be in a manner of increasing energy level. In other words, the orbitals with low energy levels are to be filled with electrons first and then the orbitals with higher energy levels. You can use this principle correctly in the first eighteen elements of the periodic table. And after that, the efficiency will start to decrease.
The Different Rules on the Electronic Configuration of Group 15 Elements
Group 15 in the periodic table consists of five elements. They are also known as nitrogen group elements. The total number of valence electrons in group 15 is five. Expanding on the electronic configuration rules, we can write the electronic configuration of group 15 elements. Let us write the electronic configuration of nitrogen, phosphorus, arsenic, antimony, and bismuth.
Electronic configuration of nitrogen:
Nitrogen is one of the two non-metallic gases in the group 15 elements. Its atomic number is 7, and its symbol is N. The nitrogen atom has an s-orbital with two electrons and p-subshell with three electrons. This configuration is because to pair with other electrons, the p subshell needs to be half-filled. Its electronic configuration is as follows-
\[\left [ He \right ]\]2s22p3
Electronic configuration of phosphorus:
Phosphorus is another metallic gas in group 15 elements. It has an atomic number of 15, and its symbol is P. The electronic configuration of phosphorus is as follows-
\[\left [ Ne \right ]\]3s23p3
Electronic configuration of arsenic:
Arsenic is the third element in the group 15 elements. Its atomic number is 33, and its symbol is As. Its electronic configuration is as follows-
\[\left [ Ar \right ]\]3d104s24p3
Electronic configuration of antimony:
Antimony is the fourth element in the group 15 elements. Its atomic number is 51, and its symbol is Sb. Its electronic configuration is as follows-
\[\left [ Kr \right ]\]4d105s25p3
Electronic configuration of bismuth:
Bismuth is the last element in the group 15 elements. Its atomic number is 83, and its symbol is Bi. Its electronic configuration is as follows-
\[\left [ Xe \right ]\]4f145d106s26p3
FAQs on Electronic Configuration of Group 15 Elements
1. What is the general electronic configuration for elements in Group 15?
The general valence shell electronic configuration for all elements in Group 15 of the periodic table is ns²np³. Here, 'n' represents the principal quantum number of the outermost shell. This configuration means they have 5 electrons in their valence shell, with a completely filled 's' orbital and a half-filled 'p' orbital.
2. How do you write the electronic configuration for a specific Group 15 element, like Phosphorus (P)?
For Phosphorus (P), which has an atomic number of 15, the full electronic configuration is 1s² 2s² 2p⁶ 3s² 3p³. The valence shell is the third shell (n=3), which has the configuration 3s²3p³, matching the general formula ns²np³. The condensed configuration is written as [Ne] 3s²3p³, where [Ne] represents the stable electron core of Neon.
3. Why is the half-filled p-orbital in Group 15 elements considered exceptionally stable?
A half-filled p-orbital (p³) is considered very stable due to two main reasons:
- Symmetrical Distribution: The three electrons are placed one in each of the three p-orbitals (px, py, pz), leading to a symmetrical and balanced distribution of electron charge.
- Maximum Exchange Energy: According to Hund's rule, this arrangement allows for the maximum number of parallel spin exchanges between electrons, which releases energy and increases the overall stability of the atom.
4. How does the electronic configuration of Group 15 elements influence their common oxidation states?
The ns²np³ configuration directly explains their varied oxidation states. They can either lose all five valence electrons to show a +5 oxidation state or gain three electrons to complete their octet, showing a -3 oxidation state. They can also lose just the three 'p' electrons to show a +3 oxidation state. The stability of the +3 state increases down the group due to the inert pair effect, where the 's' electrons become reluctant to participate in bonding.
5. What are Group 15 elements also known as?
Group 15 elements, which include Nitrogen, Phosphorus, Arsenic, Antimony, and Bismuth, are also known as pnictogens. This name comes from the Greek word 'pniktos', which means 'to choke' or 'to suffocate'. This refers to the choking property of nitrogen gas, the most common element in the group.
6. How does the electronic configuration differ as we move down Group 15 from Nitrogen to Bismuth?
While the valence shell configuration remains ns²np³ for all elements, the principal quantum number 'n' increases, and inner d- and f-orbitals are added.
- Nitrogen (N): [He] 2s²2p³
- Phosphorus (P): [Ne] 3s²3p³
- Arsenic (As): [Ar] 3d¹⁰ 4s²4p³
- Bismuth (Bi): [Xe] 4f¹⁴ 5d¹⁰ 6s²6p³
7. How does the stability of Group 15's configuration compare to that of Group 14 or Group 16?
Group 15's half-filled p-orbital (np³) gives it extra stability compared to its neighbours. Group 14 has a partially-filled configuration (np²), and Group 16 has four p-electrons (np⁴). Neither of these arrangements has the symmetrical electron distribution or maximum exchange energy of a half-filled subshell. This extra stability is why Group 15 elements have higher ionization energies than expected when compared to Group 16 elements.

















