A-Level Chemistry Subject-Specific Vocabulary: A Definitive Guide | A-Level化学学科词汇权威指南

📚 A-Level Chemistry Subject-Specific Vocabulary: A Definitive Guide | A-Level化学学科词汇权威指南

In A-Level chemistry, precise terminology is not just about memorising words—it is the foundation of logical reasoning and mark-winning explanations. Examiners reward candidates who use the correct technical language in context.

在A-Level化学中，精确的术语不仅仅是记忆单词，它是逻辑推理和获得高分答案的基础。考官会给那些在上下文中使用正确技术语言的学生加分。

1. Core Terms in Atomic Structure | 原子结构核心术语

An atom is the smallest neutral particle of an element that retains the chemical properties of that element. An element consists of only one type of atom, whereas a compound is a substance made of two or more different elements chemically combined in fixed proportions.

原子是保持元素化学性质的最小的电中性粒子。元素是由一种类型的原子组成的物质，而化合物是由两种或更多种不同元素按固定比例通过化学结合形成的物质。

Isotopes are atoms of the same element with the same number of protons but different numbers of neutrons. Relative atomic mass (Ar) is the weighted mean mass of an atom compared to 1/12 the mass of a carbon-12 atom. Example: naturally occurring chlorine has two isotopes, ³⁵Cl and ³⁷Cl, giving Ar = 35.5.

同位素是同一元素的原子，质子数相同但中子数不同。相对原子质量（Ar）是原子的加权平均质量与碳-12原子质量的1/12之比。例如：天然氯有两种同位素³⁵Cl和³⁷Cl，因此Ar=35.5。

The mass number (nucleon number) is the total number of protons and neutrons in the nucleus; the atomic number (proton number) is the number of protons. The symbol notation is ᴬZX, where Z is atomic number and A is mass number.

质量数（核子数）是原子核中质子与中子的总数；原子序数（质子数）是质子的数目。符号表示为ᴬZX，其中Z是原子序数，A是质量数。

2. Stoichiometry and Moles | 化学计量与摩尔

The mole is the SI unit for amount of substance. One mole contains exactly 6.022×10²³ elementary entities (atoms, ions, molecules), which is the Avogadro constant. The amount of substance is calculated using the equation:

摩尔是物质的量的SI单位。1摩尔恰好包含6.022×10²³个基本实体（原子、离子、分子），即阿伏伽德罗常数。物质的量通过以下公式计算：

n = m / M

where n is the amount in mol, m is mass in g, and M is molar mass in g mol⁻¹.

其中n为物质的量（mol），m为质量（g），M为摩尔质量（g mol⁻¹）。

Empirical formula shows the simplest whole-number ratio of atoms in a compound; molecular formula shows the actual number of atoms of each element in a molecule. Example: empirical formula of ethanoic acid is CH₂O, molecular formula is C₂H₄O₂.

实验式表示化合物中原子最简整数比；分子式表示分子中每种元素的实际原子数。例如：乙酸的实验式是CH₂O，分子式是C₂H₄O₂。

Percentage yield = (actual yield / theoretical yield) × 100%. Atom economy = (molar mass of desired product / total molar mass of all products) × 100%. A high atom economy is more sustainable.

产率 = （实际产量/理论产量）×100%。原子经济性 = （目标产物的摩尔质量/所有产物的总摩尔质量）×100%。原子经济性越高越可持续。

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