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

化学键将分子或化合物中的原子结合在一起。当原子的价电子层中的电子被捐赠或与其他原子共享时，就会形成化学键。
例如，当原子失去或获得电子以填满其价电子层时，会形成离子键。失去电子而带正电荷的原子称为阳离子，而获得电子并带负电荷的原子则称为阴离子。
在食盐中，钠阳离子与氯阴离子之间的结合是离子键。
原子之间通过共用一个或多个价电子对而形成共价键。
例如，两个氢原子可以共享一对电子，形成一个单共价键。氧和氮可以分别共享两对和三对电子，形成双键和三键。&#160;

化学键介绍

Introduction to Chemical Bonds

化学键

化学键是由最外层能级的电子来决定的，它决定了原子的能量稳定性以及与其他原子形成化学键的趋势。内层的电子壳最多可以容纳两个电子，但是之后的两个电子壳则可以容纳最多八个电子。这就是所谓的八个电子规则，它指出，除了内层壳，原子在其价电子壳（最外层电子壳）上有八个电子时能量最稳定。

然而，并不是所有的元素都有足够的电子来填满它们的最外层壳，因此原子会与其他原子形成化学键，从而获得它们需要达到稳定电子的构造。因此，化学键是将原子组合在一起并形成分子或化合物的力。

离子键

原子可以通过获得或失去电子来填充它们的价电子壳。通过这样的方式，它们将会带电并成为离子。阳离子是失去电子的带正电原子，而带负电的原子则是通过获得电子而带负电。阳离子和阴离子的相反电荷会产生相互之间中等强度的引力，使原子在保持近距离的情况下形成离子键。离子键是不断存在的、带相反电荷的离子之间的密切关联。日常生活中的食盐就是离子键存在的一种情形。

共价键

八个电子规则的另一种实现方式是原子之间的电子进行共享从而形成共价键。在有机分子中，这种键比离子键更强大且更常见。共价键通常出现在碳基的有机分子中，例如我们的DNA和蛋白质。共价键通常也存在于水、二氧化碳和氧气等无机分子中。

氢键

当一个已经与带负电的原子（例如水分子中的氧）发生键合反应的弱正电氢原子被吸引到另一个分子的带负电原子时，便会形成氢键。自然界中常见氢键的例子是水分子之间的氢键。无论是两个雨滴合并成一个较大的水滴，还是小溪注入河流，都会发生氢键。氢键的形成是因为一个水分子中的弱负氧原子被其他两个水分子中的弱正氢原子所吸引。

此文本部分改编自 <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>

化学键  
最外层能量级的电子决定了原子的能量稳定性及其形成化学键的倾向……

Education

教育

JoVE Core

Anatomy and Physiology

解剖学与生理学

Unit 1

第 1 单元

Fundamentals of Chemistry

化学基础

KEY TERMS AND CONCEPTS

关键术语与概念

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.

How Atoms Bond to Reach Stability

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How Atoms Bond to Reach Stability

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