Table of Contents
aufbau-principle-paulis-exclusion-principle-and-hunds-rule
The Pauli exclusion principle states that no two fermions (particles with half-integer spin) can occupy the same quantum state. This principle is the basis of the periodic table of elements, as it prevents two electrons from occupying the same shell.
The Hund’s rule states that when electrons are placed in a degenerate energy level, they will spread out as evenly as possible. This rule is important in understanding the ordering of electrons in atoms.
Salient Features of the Aufbau Principle
The Aufbau principle states that the lowest energy state of an atom is its ground state, and that atoms are built up from the ground state by adding energy in the form of photons or particles. The Aufbau principle is the basis for the atomic model developed by Niels Bohr.
Electronic Configuration using the Aufbau Principle
The Aufbau principle states that electrons occupy the lowest energy levels first. This principle can be used to predict the electronic configuration of an atom.
The first step is to identify the element. Once the element is identified, the electron configuration can be determined using the Aufbau principle. The electron configuration is written in order of increasing energy level. The first energy level can hold a maximum of two electrons. The second energy level can hold a maximum of eight electrons. The third energy level can hold a maximum of eighteen electrons. The fourth energy level can hold a maximum of eight electrons.
For example, the electron configuration of carbon can be written as 1s2 2s2 2p2. This means that the carbon atom has two electrons in the first energy level, two electrons in the second energy level, and two electrons in the second energy level.
Writing the Electronic Configuration of Sulfur
The electronic configuration of sulfur is 1s2 2s2 2p6 3s2 3p4.
Writing the Electronic Configuration of Nitrogen
Nitrogen is a colorless, odorless, and tasteless gas. It is the seventh most abundant element in the universe. Nitrogen is the most abundant element in the Earth’s atmosphere.
Nitrogen has an atomic number of 7 and an atomic weight of 14.0067. Its electronic configuration is 1s2 2s2 2p3.
Paulis Exclusion Principle
The Pauli exclusion principle states that no two particles can occupy the same quantum state.
Hund’s Rule
If two or more substances are in contact with each other, the more volatile substance will vaporize and the less volatile substance will remain.
This rule is also known as the “Le Chatelier’s Principle.”
