[Chemistry Class Notes] on Electronic Configuration of Group 15 Elements Pdf for Exam

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.

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

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

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

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

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