Introduction to the Study of Atoms: Energy Levels and Sublevels

Relevance of the Topic

The study of atoms, their energy levels and sublevels, is one of the fundamental pillars of Modern Chemistry. This structure, proposed by Niels Bohr, is crucial to understand how atoms interact and form molecules, and consequently, how substances and chemical reactions occur. Understanding these concepts provides valuable insight into the nature of matter and the wide range of phenomena it can manifest.

Contextualization

Within the Chemistry curriculum, the study of atoms, energy levels and sublevels follows the study of the general structure of matter and precedes the study of chemical bonds. It is a crucial transition point, where students move from a macroscopic view of matter to a more microscopic and internal view. This understanding is necessary to comprehend how and why atoms bond to form molecules and thus how substances and chemical compounds behave. Moreover, these concepts will be fundamental in future Chemistry studies, such as stoichiometry and a more advanced understanding of chemical reactions.

Theoretical Development

Components

• Energy levels: are the "allowed" positions of electrons in an atom, according to Bohr's model. Each level is characterized by a principal quantum number (represented by n) that defines its energy. The higher the value of n, the greater the energy of the electron and its distance from the nucleus. They are similar to Rutherford's "orbits," but less rigid.

• Electrons: subatomic particles with a negative charge that orbit around the nucleus of an atom. In an atom, the total number of electrons equals the atomic number. The distribution of electrons among the levels is crucial for determining the physical and chemical properties of the element.

• Energy sublevels: are divisions within each energy level that correspond to how electrons are distributed in that level. There are four types of sublevels: s, p, d, and f, each capable of "holding" a specific number of electrons. These sublevels are graphically represented as "boxes" (indicating each sublevel) containing arrows (representing electrons).

Key Terms

• Atomic level: represents the location and relative energy of electrons within an atom. It is defined by the principal quantum number (n), which can have values from 1 to 7.

• Principal quantum number (n): defines the energy level where the electron is located. In Bohr's model, the value of n is related to the radius of the orbit in which the electron is spinning.

• Sublevels (s, p, d, f): divisions of energy levels that indicate the shape of the orbital where the electron can be found. Each sublevel has a maximum number of electrons it can contain (2 for s, 6 for p, 10 for d, and 14 for f).

Examples and Cases

• Case of the carbon atom (C): Carbon has 6 electrons, which are distributed in 2 in the first energy level (n=1) and 4 in the second energy level (n=2). The second energy level is divided into an s sublevel (with 2 electrons) and a p sublevel (with 4 electrons). The electronic distribution of carbon can be represented as 1s²2s²2p².

• Case of the iron atom (Fe): Iron has 26 electrons, which are distributed in 2 in the first energy level, 8 in the second energy level, and 4 in the third energy level. The third energy level is divided into an s sublevel (with 2 electrons), a p sublevel (with 6 electrons), and a d sublevel (with 2 electrons). The electronic distribution of iron can be represented as 1s²2s²2p⁶3s²3p⁶4s²3d⁶.

Remember that distorting these concepts can lead to a misunderstanding of chemical phenomena, therefore, mastering the understanding of these elements and their interactions is essential for a solid mastery of chemical sciences.

Detailed Summary

Relevant Points

• Bohr Model: Atoms consist of a positively charged nucleus surrounded by electrons in circular orbits. These orbits, called energy levels, are defined by quantum numbers and represent energy states that an electron can assume.

• Principal Quantum Number (n): Defines the energy level where the electron is located. The values of n can range from 1 to 7, corresponding to the seven periods of the periodic table.

• Energy Sublevels (s, p, d, f): Divisions of energy levels that represent the shape and energy of the orbitals. Each sublevel has a maximum number of electrons it can contain (s = 2, p = 6, d = 10, f = 14).

• Electronic Distribution: Represents the number of electrons in each energy sublevel. It is essential for determining the chemical and physical properties of an element.

Conclusions

• The distribution of electrons in energy levels and sublevels follows a pattern that can be determined by the atomic number of the element.

• The distance of electrons from the nucleus increases as the principal quantum number (n) increases.

• The correct electronic distribution of atoms provides information about the arrangement of electrons and can be used to predict the chemical behavior of elements.

Exercises

1. Electronic Distribution of Oxygen (O): In Bohr's model, the oxygen atom has 8 electrons. What is the correct electronic distribution of this atom?

2. Energy Level of Phosphorus (P): Determine the energy level where the electrons are located in a phosphorus atom, and how many electrons are present in it.

3. Energy Sublevels of Potassium (K): The potassium atom has 19 electrons. In which energy sublevels are these electrons located?