4.1. Chemical Bonds: Octet Theory

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The octet theory is one of the main bases for the study of chemical bonds in the field of Chemistry. This theory, proposed by Gilbert Newton Lewis in 1916, posits that atoms tend to combine in such a way as to have eight electrons in their valence shell, achieving a stable electronic configuration similar to that of noble gases.

The electrons in the valence shell are responsible for the chemical properties of elements, as they participate in chemical bonds. Therefore, understanding the octet theory is fundamental to understanding how atoms interact with each other to form chemical compounds.

There are three main types of chemical bonds: ionic, covalent, and metallic. Each of these bindings occurs in a different way, but all are guided by the principle of octet theory.

Ionic Bond

In an ionic bond, an atom donates one or more electrons to another atom. This usually occurs between a metal and a non-metal. The metal, which has few electrons in its valence shell, donates electrons to the nonmetal, which has many electrons in its valence shell. The result is the formation of ions, which are atoms with an electrical charge. Oppositely charged ions attract each other, forming an ionic compound.

Covalent Bond

In a covalent bond, two atoms share one or more pairs of electrons. This usually occurs between two non-metals. Each atom contributes one electron to the shared pair, so that both atoms achieve a stable electron configuration. The result is the formation of a molecule.

Metallic Connection

In metallic bonding, the valence shell electrons of the metal atoms are free to move through the material. This results in a "cloud" of electrons that surrounds the metal atoms, allowing electricity and heat to conduct.

It is important to note that octet theory does not apply to all elements. Some elements, such as hydrogen, lithium, and beryllium, achieve a stable electron configuration with two electrons in their valence shell. Also, some elements of transition groups can have more than eight electrons in their valence shell.

Despite these exceptions, the octet theory is a useful tool for predicting how atoms will combine to form chemical compounds. Understanding this theory is essential for studying chemistry and preparing for the ENEM test.

In short, octet theory is a fundamental foundation for understanding chemical bonds. It allows us to predict the combinations of atoms and the formation of compounds, providing a deeper understanding of the principles of chemistry. Studying and understanding octet theory is therefore a crucial step in preparing for the ENEM test.

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464.2. Chemical Bonds: Ionic bond