道尔顿的原子论

1808 年，英国科学家和化学家约翰·道尔顿提出道尔顿的原子假说，这是一种关于物质性质的科学理论。它断言所有物质都是由原子组成的，原子是微小的、不可分割的单位。根据道尔顿的原子论，所有物质都是由原子组成的，原子是坚不可摧、不可分割的积木。虽然一种元素的原子大小和质量都相同，但其他元素的原子大小和重量不同。

道尔顿的原子论

对于科学爱好者来说，最重要的研究领域之一一直很重要。长期以来，科学家和哲学家一直试图让事情变得更容易理解。他们对构成物质的基本粒子及其性质、结构和其他特征感到好奇。结果，发展了各种原子理论。

德谟克利特被认为是第一个假设物质由粒子组成的人。这些粒子被命名为atomos，在希腊语中意为不可分割的。德谟克利特的原子论就是以此为基础的。由于缺乏技术设置，当时科学家们对这个想法的了解很少。

两千多年后，科学家约翰道尔顿展示了简化物质的工作。约翰道尔顿在 1808 年提出了著名的道尔顿原子理论。在一篇题为“新化学哲学”的论文中，他发表了这个想法。当然，当时的哲学很新颖。让我们看一下该理论的假设。

道尔顿根据两个定律制定了他的理论：质量守恒定律和常数成分定律。

1. 质量守恒定律： 1789 年，Antoine Laurent Lavoisier 发现了质量守恒定律。质量守恒定律说，物质既不能不被创造，也不能不毁灭，而是可以在一个封闭的系统中从一种改变到另一种改变。我们使用质量守恒定律来平衡线性方程。
2. 恒定成分定律：恒定成分定律说，纯化合物始终具有相同比例的相同元素。例如，具有分子式 NaCl 的食盐含有相同比例的钠和氯，而不是我们想要制作多少盐的事实。

Postulates of Dalton’s Atomic Theory 

The postulates of Dalton’s theory may be stated as follows:

1. All matter is composed of atoms, which are indivisible: According to Dalton, the law of conservation of mass and the law of definite proportions can be explained using the idea of atoms. He proposed that all matter is made of tiny indivisible particles called atoms, which he imagined as “solid and movable particles”
2. All atoms of a given element are identical in mass and properties: Dalton proposed that every single atom of a particular element, such as copper, potassium etc, is the same as every other atom of that particular element. e.g. A potassium atom is different from an oxygen atom. Elements may share some similar boiling points, melting points, but no two elements have the same exact same set of properties.
3. Compounds are combinations of two or more different types of atoms: In the third part of Dalton’s atomic theory, he proposed that compounds are combinations of two or more different types of atoms. An example of such a compound is Common Salt. Common Salt is a combination of two different types of elements with varying physical and chemical properties. The first, sodium, is a highly reactive metal. The second, chlorine, is a toxic gas. When they react, the atoms combine in a 1:1 ratio to form white crystals of NaCl.
4. A chemical reaction is a rearrangement of atoms: In the last postulate, Dalton suggested that chemical reactions neither destroy and nor create atoms. They just rearranged the atoms. Using our salt example again, when sodium combines with chlorine to make salt, both the sodium and chlorine atoms still exist. They simply rearrange to form a new compound.

道尔顿原子论的优点：

• 道尔顿的理论提供了区分元素和化合物的基本思想。
• 道尔顿的原子论。不违反倍数比例定律、质量守恒定律和恒比例定律。

道尔顿原子论的缺点：

• 道尔顿指出原子是不可分割的，它们可以进一步分为电子、质子和中子。
• 道尔顿指出，给定元素的原子具有完全相同的质量。但是，众所周知，即使是相同元素的原子也可以像同位素一样具有不同的质量。
• 道尔顿指出，不同元素的原子可以有不同的质量。但是，众所周知，即使是不同元素的原子也可以像等压线一样具有相同的质量。

示例问题

问题1：分子是否有可能由单个原子组成？

回答：

An electrically neutral group of two or more atoms held together by chemical bonds is the most basic definition of molecule. In that sense, no, by nature, a molecule can not be formed from a single atom.

问题2：盐（NaCl）是分子吗？

回答：

Molecules are subject to molecular bonds. Something like table salt (NaCl) is a compound because it is made of more than one type of element (sodium and chlorine), but it is not a molecule because it is an ionic bond that holds NaCl together. We can say sodium chloride is an ionic compound.

问题3：原子和分子有什么区别？

回答：

A tiny particle of a chemical element is called an atom, which may or may not exist independently. Molecules refer to the group of atoms that the bond binds together, representing the smallest unit in a compound. Two or more identical or distinct atoms are chemically bonded.

问题4：什么是质量数？

回答：

The complete amount is in the protons and neutrons in the nucleus of an atom. For example, nitrogen has seven protons in its nucleus and seven neutrons, supplying it with 14 masses.

问题5：谁发现了原子序数？

回答：

The number of protons (positive charges) in the nucleus of an atom is given by its atomic number. This term was first introduced by Henry Gwyn-Jefferies Moseley.

问题6：质子和电子的质量相同吗？

回答：

Electrons are a sort of negative-charged subatomic particle. Protons and neutrons have about the same mass as electrons, yet they are both significantly more massive (approximately 2,000 times as massive as an electron). A proton’s positive charge is the same magnitude as an electron’s negative charge.