Name: electronegativity in polar covalent bonds
Uploaded: 2025-05-22T09:05:32.000Z
Duration: 2 min 24 s
Channel: JoVE

K12 Standards

Arizona Science Standards

High School

Physical Science

HS.P1

HS.P1U1.2

Polar Covalent Bonds

Los no metales tienen altas energías de ionización, lo que dificulta la transferencia de electrones de valencia de un átomo a otro. Por lo tanto, los no metales tienden a compartir electrones de valencia entre átomos, formando enlaces covalentes.
El par compartido de electrones en el enlace covalente se denomina par de enlace. Los electrones de valencia que no participan en el enlace se denominan pares solitarios o electrones no enlazantes.
De acuerdo con la regla del octeto, cuando ciertos átomos tienen menos de ocho electrones en su capa de valencia, reaccionan para formar compuestos estables logrando la configuración del gas noble más cercano.
Por ejemplo, en una molécula de amoníaco, el nitrógeno requiere tres electrones más para alcanzar su configuración de gas noble más cercana, o un octeto, mientras que el hidrógeno necesita un electrón más para alcanzar su configuración de gas noble más cercana, o un dúo. Por lo tanto, el átomo de nitrógeno forma enlaces simples con tres átomos de hidrógeno.
Por otro lado, las moléculas de dióxido de carbono y monóxido de carbono se mantienen unidas por dobles y triples enlaces carbono-oxígeno, respectivamente. La formación de los enlaces dobles y triples asegura que cada uno de los átomos constituyentes logre la configuración de gas noble más cercana.
Cuando se forman enlaces covalentes entre dos átomos de diferentes elementos, el átomo más electronegativo atrae a los electrones con más fuerza, formando un enlace covalente polar. La capacidad de un átomo para atraer electrones hacia sí mismo se llama electronegatividad. Cuanto mayor sea la diferencia en electronegatividad, más polar será el enlace.
La escala de Pauling proporciona el valor de electronegatividad para cada elemento en función de los cálculos de energía de enlace. El nitrógeno es más electronegativo que el carbono, que a su vez es más electronegativo que el hidrógeno.
Así, en un enlace covalente entre carbono y nitrógeno, cuanto más nitrógeno electronegativo atrae los electrones compartidos hacia sí mismo, mientras que, en un enlace entre carbono e hidrógeno, más carbono electronegativo atrae la densidad de electrones lejos del hidrógeno menos electronegativo.

Adaptado de <a href="https://openstax.org/books/chemistry-2e/pages/7-2-covalent-bonding">Openstax, Chemistry 2e, Section 7.2: Covalent Bonds</a>

enlaces covalentes polares

Los enlaces covalentes se forman entre dos átomos cuando ambos tienen tendencias similares a atraer electrones hacia sí mismos (es decir, cuando ambos átomos tienen energías de ionización y afinidades electrónicas idénticas o bastante similares). Los átomos no metálicos frecuentemente forman enlaces covalentes con otros átomos no metálicos. Por ejemplo, la molécula de hidrógeno, H_2, contiene un enlace covalente entre sus dos átomos de hidrógeno. Cuando dos átomos de hidrógeno separados con una energía potencial particular se acercan, sus orbitales de valencia (1s) comienzan a superponerse. Los electrones individuales de cada átomo de hidrógeno interactúan con ambos núcleos atómicos, ocupando el espacio alrededor de ambos átomos. La fuerte atracción de cada electrón compartido hacia ambos núcleos estabiliza el sistema y la energía potencial disminuye a medida que disminuye la distancia de enlace. Si los átomos continúan acercándose, las cargas positivas de los dos núcleos comienzan a repelerse y la energía potencial aumenta. La longitud del enlace está determinada por la distancia a la que se alcanza la energía potencial más baja. El hecho de que un enlace sea apolar o covalente polar está determinado por una propiedad de los átomos enlazantes llamada electronegatividad.


 Los valores de electronegatividad de los elementos fueron propuestos por uno de los químicos más famosos del siglo XX: Linus Pauling. La electronegatividad es una medida de la tendencia de un átomo a atraer electrones (o densidad electrónica) hacia sí mismo. La electronegatividad determina cómo se distribuyen los electrones compartidos entre los dos átomos de un enlace. Cuanto más fuertemente atrae un átomo a los electrones de sus enlaces, mayor será su electronegatividad. Describe con qué fuerza un átomo atrae los electrones en un enlace. Es una magnitud adimensional que se calcula, no se mide. Pauling derivó los primeros valores de electronegatividad comparando las cantidades de energía necesarias para romper diferentes tipos de enlaces. Los electrones de un enlace covalente polar se desplazan hacia el átomo más electronegativo; por tanto, el átomo más electronegativo es el que tiene carga negativa parcial. Cuanto mayor es la diferencia de electronegatividad, más polarizada es la distribución de electrones y mayores son las cargas parciales de los átomos.

Enlaces covalentes polares

Los enlaces covalentes se forman entre dos átomos cuando ambos tienen tendencias similares a atraer electrones hacia sí mismos (es decir, cuando ambos átomos tienen idénticos o ...

Education

Educación

JoVE Core

Organic Chemistry

Química Orgánica

Unit 1

Unidad 1

Covalent Bonding and Structure

Enlace covalente y estructura

KEY TERMS AND CONCEPTS

TÉRMINOS Y CONCEPTOS CLAVE

electronegativity in polar covalent bonds

Polar covalent bonds form when atoms share electrons unevenly. This happens in covalent bonds between atoms that have similar, but not identical, tendencies to attract electrons. Nonmetal atoms often make these bonds with other nonmetals. Hydrogen gas, H2, is a simple example of a covalent bond between two hydrogen atoms.

A covalent bond begins when two atoms move close enough for their valence orbitals to overlap. In hydrogen, the 1s orbitals overlap and the single electrons on each atom interact with both nuclei. The shared electrons are attracted to both nuclei, which lowers the potential energy of the system. As the atoms get closer, the bond reaches its length at the point of lowest potential energy.

If the atoms move too close, the positive nuclei begin to repel each other. That repulsion raises the potential energy. The balance between attraction and repulsion sets the bond length. This balance helps explain why covalent bonds are stable at a specific distance.

Whether a covalent bond is polar or nonpolar depends on electronegativity. Electronegativity is an atom’s tendency to attract electron density toward itself. It is a calculated, dimensionless value, not a measured one. Linus Pauling proposed the first electronegativity values by comparing the energy needed to break different bonds.

In a polar covalent bond, the shared electrons shift toward the more electronegative atom. That atom carries the partial negative charge. The other atom carries the partial positive charge. When the electronegativity difference is larger, the bond becomes more polarized and the partial charges become larger.

Electronegativity in Polar Covalent Bonds

electronegativity-in-polar-covalent-bonds

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Electronegativity in Polar Covalent Bonds | JoVE K12

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Electronegativity in Polar Covalent Bonds

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