📚 WJEC Year 12 Chemistry: Quick Memorisation Guide to Key Terminology | WJEC 12年级化学：关键术语速记指南
Mastering the precise language of chemistry is as important as understanding the equations themselves. This guide breaks down the essential terminology for the WJEC Year 12 specification into bite-sized, memorable chunks, pairing definitions with simple memory hooks so you can recall them confidently under exam pressure.
掌握化学的准确用词和理解方程式同样重要。本指南将 WJEC 12 年级考纲中的核心术语拆解成易于消化的模块，将定义与简单的记忆钩子配对，让你在考试压力下也能自信地回忆起来。
1. Fundamental Quantities and the Mole | 基本量与摩尔
Relative Atomic Mass (Aᵣ): The weighted mean mass of an atom of an element compared with 1/12th the mass of an atom of carbon-12. Think of it as the ‘average mass number’ on the periodic table, not just the mass number of one isotope.
相对原子质量（Aᵣ）：元素一个原子的加权平均质量与一个碳-12原子质量的 1/12 之比。可以把它看作元素周期表上看到的“平均质量数”，而不是单一同位素的质量数。
Relative Molecular Mass (Mᵣ): The sum of the relative atomic masses of all the atoms in a molecule. For giant structures, we say relative formula mass instead, but it is calculated the same way.
相对分子质量（Mᵣ）：一个分子中所有原子的相对原子质量之和。对于巨型结构，我们用相对式量来代替，但计算方法相同。
Mole (mol): The amount of substance that contains exactly 6.022 × 10²³ elementary entities. A mole of anything is like a ‘chemist’s dozen’ – it is simply a very large, fixed counting unit.
摩尔（mol）：物质所含基本单元数恰好等于 6.022×10²³ 的物质的量。一摩尔任何东西就像“化学家的打（dozen）”——它只是一个非常大且固定的计数单位。
Empirical Formula: The simplest whole-number ratio of atoms of each element in a compound. Mnemonic: ‘Empirical = Elementary ratio’.
实验式（最简式）：化合物中各元素原子的最简整数比。助记：“实验式 = 最简比例（Empirical = Elementary ratio）”。
Molecular Formula: The actual number of atoms of each element in a molecule. For ethane, empirical is CH₃, molecular is C₂H₆.
分子式：分子中每种元素原子的实际数目。以乙烷为例，实验式是 CH₃，分子式是 C₂H₆。
2. Atomic Structure and Isotopes | 原子结构与同位素
Isotopes: Atoms of the same element with the same number of protons but different numbers of neutrons. ‘Iso’ means same, ‘topos’ means place – they occupy the same place on the periodic table.
同位素：质子数相同但中子数不同的同种元素原子。“Iso”意为相同，“topos”意为位置——它们在周期表中占据同一位置。
Relative Isotopic Mass: The mass of one isotope compared with 1/12th the mass of an atom of carbon-12. Unlike Aᵣ, this refers to a single isotope, e.g. ³⁵Cl = 34.97.
相对同位素质量：一个同位素原子的质量与碳-12原子质量的 1/12 之比。不同于 Aᵣ，它指向单一同位素，例如 ³⁵Cl = 34.97。
Mass Spectrometry: A technique used to determine relative isotopic masses and abundance. Picture it as a ‘weighing machine for atoms’ that also tells you how much of each isotope is present.
质谱法：用于测定相对同位素质量和丰度的技术。可以想象为“原子的称重机”，同时还能告诉你每种同位素有多少。
First Ionisation Energy: The energy required to remove one electron from each atom in one mole of gaseous atoms to form one mole of gaseous 1+ ions. Remember the state symbol (g) and the ‘per mole’ – it is always for 1 mol of atoms.
第一电离能：从气态原子中每摩尔原子各移除一个电子，形成一摩尔气态 1+ 离子所需的能量。注意状态符号 (g) 和“每摩尔”——它总是针对 1 mol 原子的。
Electron Shell/Orbital: Regions around the nucleus where electrons are likely to be found. Think of shells as floors in an apartment block, subshells as rooms, and orbitals as specific seating spots, each holding up to two electrons.
电子壳层/轨道：原子核周围电子可能出现区域。可以把壳层想象成公寓的楼层，亚层是房间，轨道是特定的座位，每个座位最多容纳两个电子。
3. Electron Configuration and Ionisation Energies | 电子排布与电离能
Aufbau Principle: Electrons fill orbitals in order of increasing energy, from lowest to highest. ‘Aufbau’ means ‘building up’ in German – you build the configuration step by step.
构造原理：电子按能量递增的顺序填入轨道，从低能级到高能级。“Aufbau”在德语中意为“构建”——你一步一步地构建电子排布。
Hund’s Rule: Electrons prefer to occupy separate orbitals of the same subshell with parallel spins before pairing up. Imagine passengers on an empty bus: they will each take their own double seat before sharing.
洪特规则：电子在成对之前，倾向于以自旋平行的方式占据同一亚层的不同轨道。想象一下空公交车上的乘客：他们会先各自占一个双人座，然后再共享座位。
Pauli Exclusion Principle: No two electrons in an atom can have the same four quantum numbers; an orbital holds at most two electrons with opposite spins. Simply, ‘one pair per box, arrows up and down’.
泡利不相容原理：一个原子中不可能有两个电子的四个量子数完全相同；一个轨道最多容纳两个自旋相反的电子。简单地说：“一个格子里最多放一对，箭头一上一下”。
Successive Ionisation Energies: The energies needed to remove electrons one after another. A large jump in energy indicates that an electron is being removed from an inner, full shell – a powerful clue to the element’s group.
逐级电离能：逐个移除电子所需的能量。能量的巨大跳跃表示一个电子正从内层满壳层被移除——这是判断元素位于哪一族的有力线索。
4. Bonding: Ionic, Covalent and Metallic | 化学键：离子键、共价键与金属键
Ionic Bonding: The electrostatic attraction between oppositely charged ions formed by electron transfer. Key words: ‘electrostatic’, ‘oppositely charged ions’, ‘lattice’. Do not say ‘molecules’!
离子键：通过电子转移形成的带相反电荷离子之间的静电引力。关键词：“静电”、“相反电荷离子”、“晶格”。不要说“分子”！
Covalent Bonding: The strong electrostatic attraction between a shared pair of electrons and the nuclei of the bonded atoms. It is still electrostatic – the shared pair pulls both nuclei together.
共价键：共用电子对与成键原子核之间的强静电引力。它本质上仍然是静电作用——共用电子对把两个核拉在一起。
Dative Covalent (Coordinate) Bond: A covalent bond in which both electrons come from the same atom. Once formed, it is indistinguishable from an ordinary covalent bond. Think NH₄⁺ or H₃O⁺.
配位共价键（配位键）：两个电子均来自同一原子的一种共价键。一旦形成，它与普通共价键无法区分。回想 NH₄⁺ 或 H₃O⁺。
Metallic Bonding: The electrostatic attraction between a lattice of positive metal ions and a sea of delocalised electrons. This ‘sea’ model explains electrical conductivity and malleability.
金属键：正金属离子晶格与离域电子海之间的静电引力。这个“电子海”模型解释了导电性和延展性。
Electronegativity: The ability of an atom to attract the bonding pair of electrons in a covalent bond. Fluorine is the most electronegative; use the FONClBrISCH trend as a reminder.
电负性：一个原子在共价键中吸引成键电子对的能力。氟的电负性最高；用 FONClBrISCH 趋势来记。
5. Shapes of Molecules and Polarity | 分子形状与极性
VSEPR Theory: Valence Shell Electron Pair Repulsion – electron pairs repel and arrange themselves as far apart as possible to minimise repulsion. This decides the shape. ‘Bonding pairs + lone pairs = number of charge clouds’.
价层电子对互斥理论（VSEPR）：电子对互相排斥，并尽可能远地排列以减小排斥。这决定了分子形状。“成键电子对 + 孤电子对 = 电荷云数量”。
Lone Pair: A pair of electrons in the outer shell that is not involved in bonding. Lone pairs repel more strongly than bonding pairs, compressing bond angles by about 2.5° per lone pair.
孤电子对：外层中不参与成键的一对电子。孤电子对的排斥力比成键电子对更强，每多一对孤电子对，键角约被压缩 2.5°。
Bond Polarity: Unequal sharing of electrons due to a difference in electronegativity, creating a dipole. If dipoles cancel by symmetry, the molecule is non-polar overall, like CO₂.
键的极性：由于电负性差异导致电子不均匀共享，从而产生偶极。如果偶极因对称性而相互抵消，分子整体就是非极性的，例如 CO₂。
Linear, Bent, Trigonal Planar, Tetrahedral: Common shapes with bond angles 180°, 104.5–118°, 120°, 109.5°. Memorise them by counting charge clouds: 2 clouds = linear, 3 with one lone pair = bent, 4 with no lone pairs = tetrahedral.
直线形、角形、三角平面形、四面体形：常见形状分别对应键角 180°、104.5–118°、120°、109.5°。通过数电荷云来记：2 个云 = 直线形，3 个云含一孤对 = 角形，4 个云无孤对 = 四面体形。
6. Intermolecular Forces | 分子间作用力
Induced Dipole–Dipole (London) Forces: Temporary attractive forces caused by fluctuating electron distributions. They exist between all molecules and increase with Mr and surface contact. ‘Everything has London forces’.
诱导偶极-偶极力（伦敦力）：由电子分布波动引起的暂时性吸引力。它们存在于所有分子之间，且随着相对分子质量和接触面积的增加而增大。“万物皆有伦敦力”。
Permanent Dipole–Dipole Forces: Attractions between the permanent δ+ and δ− of polar molecules. Stronger than London forces in similar‑sized molecules. Think of them as tiny magnets lining up.
永久偶极-偶极力：极性分子中永久性的 δ+ 和 δ− 之间的吸引力。在分子大小相近时比伦敦力强。可以想象成小磁铁相互对齐。
Hydrogen Bonding: The strongest type of intermolecular force, occurring when H is bonded to N, O, or F and attracted to a lone pair on a neighbouring N, O, or F. Remember ‘H bonds with NOF’.
氢键：最强的分子间作用力，发生在 H 与 N、O 或 F 成键，并被邻近分子的 N、O 或 F 上的孤电子对吸引时。记住“H 会和 NOF 形成氢键”。
7. Energetics: Enthalpy Changes | 能量学：焓变
Enthalpy Change (ΔH): The heat energy transferred in a reaction at constant pressure. Standard conditions are 100 kPa, 298 K, and solutions at 1 mol dm⁻³. ΔH is negative for exothermic, positive for endothermic.
焓变（ΔH）：在恒压条件下反应中传递的热量。标准条件是 100 kPa，298 K，溶液浓度为 1 mol dm⁻³。放热反应 ΔH 为负，吸热反应 ΔH 为正。
Standard Enthalpy of Combustion (ΔH_c°): The enthalpy change when one mole of a substance is completely burned in excess oxygen under standard conditions. Always exothermic.
标准燃烧焓（ΔH_c°）：在标准条件下，一摩尔物质在过量氧气中完全燃烧时的焓变。总是放热反应。
Standard Enthalpy of Formation (ΔH_f°): The enthalpy change when one mole of a compound is formed from its elements in their standard states. Elements by definition have ΔH_f° = 0.
标准生成焓（ΔH_f°）：在标准状态下，由元素生成一摩尔化合物时的焓变。根据定义，元素的 ΔH_f° = 0。
Hess’s Law: The total enthalpy change for a reaction is independent of the path taken. It allows you to build an enthalpy cycle diagram, just like completing a jigsaw puzzle with arrows.
盖斯定律：反应的总焓变与所采取的路径无关。你可以构建一个焓循环图，就像完成一个箭头拼图一样。
Mean Bond Enthalpy: The energy required to break one mole of a given bond, averaged over a range of compounds. It is always endothermic (bond breaking takes energy).
平均键焓：断开一摩尔某种化学键所需的能量，是在一系列化合物中的平均值。它总是吸热的（断键需要能量）。
8. Kinetics: Rates and Collision Theory | 动力学：速率与碰撞理论
Rate of Reaction: The change in concentration of a reactant or product per unit time. Usually measured in mol dm⁻³ s⁻¹. Faster rate = steeper gradient on a concentration‑time graph.
反应速率：单位时间内反应物或产物浓度的变化。通常以 mol dm⁻³ s⁻¹ 为单位。速率越快，浓度-时间图上的斜率越陡。
Collision Theory: For a reaction to happen, particles must collide with sufficient energy (≥ activation energy) and in the correct orientation. ‘Cash and orientation’.
碰撞理论：反应若要发生，粒子必须碰撞，且具有足够的能量（≥活化能）以及正确的取向。简记为“现金（能量）和朝向”。
Activation Energy (Eₐ): The minimum energy that colliding particles need for a reaction to occur. On a Maxwell‑Boltzmann distribution, it is the energy to the right of the curve’s hump where successful collisions take place.
活化能（Eₐ）：发生反应的碰撞粒子所需的最低能量。在麦克斯韦-玻尔兹曼分布中，它就是曲线峰右侧、足以发生有效碰撞的那部分能量。
Catalyst: A substance that increases the rate of a reaction without being used up, by providing an alternative reaction pathway with a lower activation energy. Not consumed, so it appears unchanged chemically at the end.
催化剂：一种通过提供较低活化能的替代反应路径来增加反应速率，且自身不被消耗的物质。它不被消耗，因此反应结束时化学性质保持不变。
Maxwell-Boltzmann Distribution: A curve showing the distribution of molecular energies in a gas at a given temperature. The area under the curve beyond Eₐ represents the fraction of particles that can react.
麦克斯韦-玻尔兹曼分布：显示给定温度下气体中分子能量分布的曲线。曲线在 Eₐ 右侧的面积代表能发生反应的粒子比例。
9. Chemical Equilibrium | 化学平衡
Dynamic Equilibrium: The state where the forward and reverse reactions occur at the same rate, so the concentrations of reactants and products remain constant. It is ‘dynamic’ because reactions continue to happen both ways.
动态平衡：正反应和逆反应速率相等的状态，因此反应物和产物的浓度保持恒定。之所以叫“动态”，是因为两个方向的反应仍在持续进行。
Le Chatelier’s Principle: If a system at equilibrium is subjected to a change in concentration, pressure or temperature, the position of equilibrium will shift to oppose that change. Think ‘the system does the opposite to what you do’.
勒夏特列原理：如果处于平衡状态的体系受到浓度、压力或温度的改变，平衡位置将朝减弱这一改变的方向移动。可以想成“系统跟你对着干”。
Equilibrium Constant (Kc): A ratio that relates the concentrations of products to reactants at equilibrium, each raised to the power of their stoichiometric coefficients. Kc is only affected by temperature.
平衡常数（Kc）：表示平衡时产物浓度与反应物浓度比值的量，各浓度以其计量系数为指数。Kc 只受温度影响。
Homogeneous vs Heterogeneous Equilibria: Homogeneous means all reactants and products are in the same phase (e.g., all gases); heterogeneous means they are in different phases. Kc expressions only include gaseous and aqueous species.
均相平衡与非均相平衡：均相指所有反应物和产物处于同一相态（例如全是气体）；非均相指处于不同相态。Kc 表达式中只包含气态和溶液态物种。
10. Redox Reactions | 氧化还原反应
Oxidation: Loss of electrons, or an increase in oxidation number. OIL RIG: Oxidation Is Loss, Reduction Is Gain (of electrons).
氧化：失去电子，或氧化数升高。OIL RIG：氧化是失电子（Oxidation Is Loss），还原是得电子（Reduction Is Gain）。
Reduction: Gain of electrons, or a decrease in oxidation number. A reducing agent is itself oxidised, and an oxidising agent is itself reduced – ‘agent does the action on the other’.
还原：得到电子，或氧化数降低。还原剂自身被氧化，氧化剂自身被还原——“试剂对他人施加作用”。
Oxidation Number/State: A number assigned to an atom in a compound indicating its degree of oxidation. Rules: elements = 0, simple ions = charge, oxygen usually −2, hydrogen usually +1, sum in neutral compound = 0.
氧化数/氧化态：赋予化合物中原子以指示其氧化程度的数字。规则：单质 = 0，简单离子 = 离子电荷，氧通常为 −2，氢通常为 +1，中性化合物中总和为 0。
Half-equation: An equation showing just the oxidation or just the reduction part of a redox reaction, with electrons explicitly shown. Always balance atoms, then balance charge with electrons.
半反应方程式：仅显示氧化还原反应中氧化部分或还原部分的方程式，并明确标出电子。始终先配平原子，再用电子配平电荷。
11. Organic Chemistry: Homologous Series and Nomenclature | 有机化学：同系物和命名
Homologous Series: A family of organic compounds with the same functional group, similar chemical properties, and a general formula. Each successive member differs by a CH₂ unit. Alkanes: CₙH₂ₙ₊₂.
同系物：具有相同官能团、相似化学性质和通式的一类有机物家族。相邻成员相差一个 CH₂ 单元。烷烃：CₙH₂ₙ₊₂。
Functional Group: An atom or group of atoms that gives a molecule its characteristic reactions. Recognise them: alkene has C=C, alcohol has −OH, carboxylic acid has −COOH.
官能团：赋予分子特征反应的原子或原子团。需要记得：烯烃有 C=C，醇有 −OH，羧酸有 −COOH。
Structural Isomers: Compounds with the same molecular formula but different structural arrangement of atoms. Three types: chain, position, and functional group isomers.
结构异构体：分子式相同但原子结构排列不同的化合物。有三种类型：碳链异构、位置异构和官能团异构。
Stereoisomerism (E-Z): Same structural formula but different spatial arrangement, specifically around a C=C double bond that cannot rotate. If the higher priority groups are on opposite sides, it is E (from German entgegen, opposite).
立体异构（E-Z）：结构式相同但空间排列不同，特指围绕不能旋转的 C=C 双键。若较高优先基团在双键两侧，即为 E 构型（来自德语 entgegen，意为相反）。
Free Radical Substitution: A mechanism for alkanes reacting with halogens in UV light. Three stages: initiation (bond homolysis), propagation (radical reacts, another formed), termination (two radicals combine).
自由基取代：烷烃在紫外光下与卤素反应的机理。分三个阶段：引发（键均裂）、增长（自由基反应，并生成新的自由基）、终止（两个自由基结合）。
12. Further Key Terms: Electrophiles, Nucleophiles and Polymers | 更多关键术语：亲电试剂、亲核试剂与聚合物
Electrophile: An electron‑pair acceptor – positively charged or electron‑deficient species that is attracted to regions of high electron density, like the C=C double bond. Think ‘lover of electrons’.
亲电试剂：电子对受体——带正电或缺电子的物种，会被电子密度高区域（如 C=C 双键）吸引。可以记作“电子爱好者”。
Nucleophile: An electron‑pair donor – rich in electrons, often negatively charged or with lone pairs. It attacks electron‑deficient carbon atoms, e.g. in haloalkane substitution.
亲核试剂：电子对供体——富含电子，常带负电荷或含有孤电子对。它会进攻缺电子的碳原子，例如在卤代烷烃取代反应中。
Addition Polymerisation: The joining of many alkene monomers by opening the C=C double bond to form a saturated, long‑chain polymer. No other products formed. Poly(ethene) is a classic example.
加成聚合：许多烯烃单体通过打开 C=C 双键相互连接，形成饱和长链聚合物。没有其他产物生成。聚乙烯是经典例子。
Condensation Polymerisation: The joining of monomers with the elimination of a small molecule, often water. Involved in making polyesters and polyamides.
缩合聚合：单体连接的同时，脱去一个小分子（通常是水）。用于制造聚酯和聚酰胺。
Curly Arrow: In mechanisms, a curly arrow shows the movement of an electron pair. Full arrow = pair of electrons; half‑headed ‘fish‑hook’ arrow = movement of a single electron (radical reactions).
弯箭头：在反应机理中，弯箭头表示电子对的移动。全箭头 = 一对电子；半箭头（鱼钩箭头）= 单个电子的移动（自由基反应中）。
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