WHAT ARE ENERGY SUBLEVELS AND HOW ARE THEY REPRESENTED? - SCIENCE - 2025

The sublevels of energy in the atom are the way in which the electrons are organized in the electronic shells, their distribution in the molecule or atom. These energy sublevels are called orbitals.

The organization of electrons in sublevels is what allows the chemical combinations of different atoms and also defines their position within the Periodic Table of Elements.

Electrons are arranged in the electronic shells of the atom in a certain way by a combination of quantum states. The moment one of these states is occupied by an electron, the other electrons must be in a different state.

Introduction

Each chemical element in the periodic table consists of atoms, which in turn are made up of neutrons, protons, and electrons. Electrons are negatively charged particles that are found around the nucleus of any atom, distributed in the orbitals of the electrons.

Electron orbitals are the volume of space where an electron has a 95% chance of meeting. There are different types of orbitals, with different shapes. A maximum of two electrons can be located in each orbital. The first orbital of an atom is where there is the greatest probability of finding electrons.

The orbitals are designated by the letters s, p, d, and f, that is, Sharp, Principle, Diffuse, and Fundamental, and they combine when atoms join together to form a larger molecule. In each shell of the atom are these combinations of orbitals.

For example, in layer 1 of the atom there are the S orbitals, in layer 2 there are S and P orbitals, within layer 3 of the atom there are S, P and D orbitals and finally in layer 4 of the atom there are all the S, P, D and F orbitals.

Also in the orbitals we find different sublevels, which in turn can store more electrons. Orbitals at different energy levels are similar to each other, but occupy different areas in space.

The first orbital and the second orbital have the same characteristics as an S orbital, they have radial nodes, they have a higher probability of spherical volume and they can only hold two electrons. However, they are located at different energy levels and thus occupy different spaces around the nucleus.

Location on the periodic table of elements

Each of the electronic configurations of the elements are unique, that is why they determine their position in the periodic table of elements. This position is defined by the period of each element and its atomic number by the number of electrons that the element's atom has.

Thus, using the periodic table to determine the configuration of electrons in atoms is key. The elements are divided into groups according to their electronic configurations as follows:

Each orbital is represented in specific blocks within the periodic table of elements. For example, the block of S orbitals is the region of alkali metals, the first group in the table and where six elements are found Lithium (Li), Rubidium (Rb), Potassium (K), Sodium (Na), Francium (Fr) and Cesium (Cs) and also hydrogen (H), which is not a metal, but a gas.

This group of elements have an electron, which is often easily lost to form a positively charged ion. They are the most active metals and the most reactive.

Hydrogen, in this case, is a gas, but it is within group 1 of the periodic table of elements since it also has only one electron. Hydrogen can form ions with a single positive charge, but pulling out its single electron requires much more energy than removing electrons from the other alkali metals. When forming compounds, hydrogen usually generates covalent bonds.

However, under very high pressures, hydrogen turns metallic and behaves like the rest of the elements in its group. This occurs, for example, inside the core of the planet Jupiter.

Group 2 corresponds to the alkaline earth metals, since their oxides have alkaline properties. Among the elements of this group we find Magnesium (Mg) and Calcium (Ca). Its orbitals also belong to the S level.

The transition metals, which correspond to groups 3 through 12 in the Periodic Table, have D-type orbitals.

The elements that go from group 13 to 18 in the table correspond to P orbitals. And finally the elements known as lanthanides and actinides have orbitals named F.

Electron location in orbitals

Electrons are found in the orbitals of the atom as a way to decrease energy. Therefore, if they seek to increase energy, the electrons will fill the main orbital levels, moving away from the nucleus of the atom.

It must be considered that electrons have an intrinsic property known as spin. This is a quantum concept that determines, among other things, the spin of the electron within the orbital. What is essential to determine your position in the energy sublevels.

The rules that determine the position of electrons in the orbitals of the atom are as follows:

• Aufbau's Principle: Electrons enter the lowest-energy orbitals first. This principle is based on diagrams of the energy levels of certain atoms.

• Pauli Exclusion Principle: An atomic orbital can describe at least two electrons. This means that only two electrons with different electron spin can occupy an atomic orbital.

This implies that an atomic orbital is an energy state.

• Hund's rule: When electrons occupy orbitals of the same energy, electrons will enter the empty orbitals first. This means that electrons prefer parallel spins in separate orbits of the energy sublevels.

The electrons will fill all the orbitals in the sublevels before encountering opposite spins.

Special electronic configurations

There are also atoms with special cases of energy sublevels. When two electrons occupy the same orbital, not only must they have different spins (as indicated by the Pauli Exclusion principle), but the coupling of the electrons slightly raises the energy.

In the case of energy sublevels, a half full and a full full sublevel reduce the energy of the atom. This leads the atom to have greater stability.

References

1. Electron Configuration. Recovered from Wikipedia.com.
2. Electronic Configurations Intro. Recovered from chem.libretexts.org.
3. Orbitals and Bonds. Recovered from chem.fsu.edu.
4. Periodic table, main group elements. Recovered from newworldencyclopedia.org.
5. Electro Configuration Principles. Recovered from sartep.com.
6. Electronic Configuration of Elements. Recovered from science.uwaterloo.ca.
7. Electron Spin. Recovered from hyperphysics.phy-astr.gsu.edu.