Name: how atoms bond to reach stability
Uploaded: 2023-06-23T15:38:43.000Z
Duration: 1 min 1 s
Channel: JoVE

Los enlaces químicos mantienen unidos los átomos de una molécula o compuesto. Los enlaces se forman cuando los electrones en la capa de valencia del átomo son donados o compartidos con otros átomos.
Por ejemplo, los enlaces iónicos se forman cuando los átomos donan o aceptan electrones, llenando su capa de valencia. Un átomo que dona electrones y se carga positivamente es un catión, mientras que uno que acepta electrones y se carga negativamente es un anión.
En la sal de mesa, la asociación entre el catión de sodio y el anión cloruro es un enlace iónico.
Los enlaces covalentes se forman entre átomos que comparten mutuamente uno o más pares de electrones de valencia.
Por ejemplo, dos átomos de hidrógeno pueden compartir un par de electrones, formando un solo enlace covalente. El oxígeno y el nitrógeno pueden compartir dos y tres pares de electrones, formando enlaces dobles y triples.

introducción a los enlaces químicos

Introduction to Chemical Bonds

Enlaces químicos

Los electrones del nivel de energía más externo determinan la estabilidad energética del átomo y su tendencia a formar enlaces químicos con otros átomos. La capa de electrones más interna tiene una capacidad máxima de dos electrones, pero las dos siguientes capas de electrones pueden tener cada una un máximo de ocho electrones. Esto se conoce como regla del octeto, que establece que, con la excepción de la capa más interna, los átomos son más estables energéticamente cuando tienen ocho electrones en su capa de valencia, la capa de electrones más externa.

Sin embargo, dado que no todos los elementos tienen suficientes electrones para llenar sus capas más externas, los átomos forman enlaces químicos con otros átomos, obteniendo así los electrones que necesitan para lograr una configuración electrónica estable. Por lo tanto, un enlace químico es la fuerza que mantiene unidos los átomos en una molécula o compuesto.

Enlaces iónicos

Los átomos pueden ganar o perder electrones para llenar su capa de valencia. Al hacerlo, se cargan eléctricamente y se les llama iones. Un catión es un átomo con carga positiva que pierde electrones, mientras que un átomo que gana electrones y se carga negativamente se llama anión. Las cargas opuestas de los cationes y los aniones ejercen una atracción mutua moderadamente fuerte que mantiene los átomos en proximidad cercana formando un enlace iónico. Un enlace iónico es una asociación continua y estrecha entre iones de carga opuesta. La sal de mesa común debe su existencia a los enlaces iónicos.

Enlaces covalentes

Otra forma de satisfacer la regla del octeto es compartiendo electrones entre átomos para formar enlaces covalentes. Estos enlaces son más fuertes y mucho más comunes que los enlaces iónicos en las moléculas de los organismos vivos. Los enlaces covalentes se encuentran comúnmente en moléculas orgánicas basadas en carbono, como nuestro ADN y proteínas. También se encuentran en moléculas inorgánicas como agua, dióxido de carbono y oxígeno.

Enlaces de hidrógeno

Se forma un enlace de hidrógeno cuando un átomo de hidrógeno débilmente cargado positivamente y ya unido a un átomo electronegativo (por ejemplo, el oxígeno en la molécula de agua) se ve atraído por otro átomo electronegativo de otra molécula. El ejemplo más común de enlace de hidrógeno en el mundo natural ocurre entre moléculas de agua. Sucede cada vez que dos gotas de lluvia se fusionan en una gota más grande o un arroyo se vierte en un río. El enlace de hidrógeno ocurre porque el átomo de oxígeno débilmente negativo en una molécula de agua se ve atraído por los átomos de hidrógeno débilmente positivos de otras dos moléculas de agua.

Este texto está parcialmente adaptado de <a href="https://openstax.org/books/anatomy-and-physiology-2e/pages/2-2-chemical-bonds?query=chemical%20bond&target=%7B%22type%22%3A%22search%22%2C%22index%22%3A0%7D#fs-id1493624">Openstax, Anatomy and Physiology 2e, Section 2.2: Chemical Bonds.</a> <a href="https://openstax.org/books/biology-ap-courses/pages/2-1-atoms-isotopes-ions-and-molecules-the-building-blocks?query=chemical%20bonds">Openstax, </a><a href="https://openstax.org/books/biology-ap-courses/pages/2-1-atoms-isotopes-ions-and-molecules-the-building-blocks?query=chemical%20bonds">Biology for AP® Courses</a><a href="https://openstax.org/books/biology-ap-courses/pages/2-1-atoms-isotopes-ions-and-molecules-the-building-blocks?query=chemical%20bonds"> Section </a><a href="https://openstax.org/books/biology-ap-courses/pages/2-1-atoms-isotopes-ions-and-molecules-the-building-blocks?query=chemical%20bonds">2.1 Atoms, Isotopes, Ions, and Molecules: The Building Blocks.</a>

Introducción a los enlaces químicos

Enlaces químicos
Los electrones del nivel de energía más externo determinan la estabilidad energética del átomo y su tendencia a formar enlaces químicos con ...

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how atoms bond to reach stability

Atoms bond to become more stable, and their outermost electrons play the biggest role in that process. The inner electron shell can hold two electrons. The next two shells can each hold eight electrons. This is called the octet rule. It states that, except for the innermost shell, atoms are most stable when their valence shell, or outer shell, has eight electrons.

When atoms do not have enough electrons to fill that outer shell, they form chemical bonds with other atoms. A chemical bond is the force that holds atoms together in a molecule or compound. These bonds let atoms reach a more stable electron arrangement.

One common type is an ionic bond. In this case, atoms gain or lose electrons to fill their valence shell. When they do this, they become ions. A cation is a positively charged ion that has lost electrons. An anion is a negatively charged ion that has gained electrons. The opposite charges attract each other and keep the ions close together. This close association forms an ionic bond. Table salt is a common example of a substance made through ionic bonding.

Another way atoms satisfy the octet rule is by sharing electrons. This creates covalent bonds. Covalent bonds are stronger and much more common than ionic bonds in the molecules of living organisms. They are found in carbon-based organic molecules such as DNA and proteins. They also occur in inorganic molecules like water, carbon dioxide, and oxygen.

Hydrogen bonds are a weaker kind of attraction. They form when a weakly positive hydrogen atom, already bonded to another electronegative atom such as oxygen, is attracted to a different electronegative atom in another molecule. Water is the most common example. Hydrogen bonding helps explain why raindrops can merge into larger beads and why a creek can flow into a river.

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How Atoms Bond to Reach Stability

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