Facts of Electron Configuration

Multiple bonding, or the sharing of two or more electron pairs, is demonstrated by the compounds ethylene and formaldehyde (each of which has a double bond), as well as acetylene and hydrogen cyanide (which both have a triple bond). Boron compounds such as BH3 and BF3 are unique in that ordinary covalent bonding does not result in the expansion of the valence shell occupancy of boron to an octet, as is the case with most other elements. This results in an increased affinity for electrons in these compounds, which makes them extremely reactive when compared to the chemicals listed above.

The Pauli Exclusion Principle is a principle that prohibits the inclusion of some individuals or groups from participating in a certain activity.

According to the Pauli exclusion principle, an orbital can only contain a maximum of two electrons, each with an opposite spin to the other.

According to another formulation, “no two electrons in the same atom have values for all four quantum numbers that are the same as each other.”

Consequently, if the primary, azimuthal, and magnetic numbers of two electrons are the same, it follows that their spins are in the opposite direction.

In accordance with the Pauli-Exclusion Principle

Wolfgang Pauli proposed that each electron can be defined by a unique set of four quantum numbers, which he called the Pauli quantum numbers. As a result, if two electrons occupy the same orbital, such as the 3s orbital, their spins must be coupled in order for the electrons to interact. Both of these particles have the same primary quantum number (n=3), the same orbital angular momentum quantum number (l=0), and the same magnetic quantum number (ml=0); but, their spin magnetic quantum numbers (ms=+1/2 and ms=-1/2) are different.

Cation and anion electronic configurations are discussed in detail.

The method by which we designate electronic configurations for cations and anions is substantially the same as the method by which we name electronic configurations for neutral atoms in their ground state. The three important rules are as follows: Aufbau Principle, Pauli-exclusion Principle, and Hund’s Rule are all observed and adhered to. It is possible to determine the electrical configuration of cations by removing electrons from the outermost p orbital first, then from the s orbital, and ultimately from the d orbitals (if any more electrons need to be removed). The ground state electronic configuration of calcium (Z=20) is 1s²2s²2p⁶3s²3p⁶4s² (for example, in the periodic table). The calcium ion (Ca2+), on the other hand, contains two less electrons. This results in Ca2+ having an electron structure of 63S23P6 instead of 1S²2S²2P⁶3S²3P⁶. Because we need to remove two electrons from the system, we begin by removing electrons from the outermost shell (n=4). The 4p subshells are all empty in this scenario, therefore we begin by removing from the s orbital, which is the 4s orbital, which is the first orbital to be removed. Ca²+ has the same electron configuration as Argon, which contains 18 electrons, and hence has the same electron configuration. As a result, we can claim that they are both isoelectronic.

According to the Aufbau Principle, the electronic configuration of anions is allocated by adding electrons to their nuclei. When the outermost orbital is fully occupied, we add electrons to fill it, and then we add more electrons to fill the subsequent higher orbital. With 17 electrons, for example, the neutral atom chlorine (Z=17) possesses 17 protons. As a result, the electrical configuration of its ground state can be represented as 1s²2s²2p⁶3s²3p⁵ on a piece of paper. A single electron has been added to the chloride ion (Cl-), bringing the total number of electrons to 18 in this case. After completing the partially filled 3p subshell, the electron moves on to the 3p orbital, which is totally filled as a result of the Aufbau Principle. Because of this, the electrical configuration for Cl- can be denoted by the letters 1s²2s²2p⁶3s²3p⁶. It should be noted that the electron configuration of the chloride ion is identical to that of the Ca2+ and Argon ions. As a result, they are all isoelectronic with respect to one another.

Conclusion

For organic chemists, this means studying molecules at the molecular level at some point, because the physical and chemical properties of a substance are ultimately explained by the structure and bonding of molecules. This module introduces some fundamental facts and ideas that are required for a study of organic molecules to take place later in the course.